[Federal Register Volume 68, Number 109 (Friday, June 6, 2003)]
[Proposed Rules]
[Pages 34036-34119]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-13749]



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Part II





Department of Labor





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Occupational Safety and Health Administration



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29 CFR Parts 1910, 1915, and 1926



Assigned Protection Factors; Proposed Rule

  Federal Register / Vol. 68, No. 109 / Friday, June 6, 2003 / Proposed 
Rules  

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DEPARTMENT OF LABOR

Occupational Safety and Health Administration

29 CFR Parts 1910, 1915, and 1926

[Docket No. H049C]
RIN 1218-AA05


Assigned Protection Factors

AGENCY: Occupational Safety and Health Administration (OSHA), 
Department of Labor.

ACTION: Proposed rule; request for comments and scheduling of informal 
public hearings.

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SUMMARY: OSHA is proposing to revise its existing Respiratory 
Protection Standard to add definitions and specific requirements for 
assigned protection factors (APFs) and maximum use concentrations 
(MUCs). The proposed revisions also would supersede the respirator 
selection provisions of existing substance-specific standards with 
these new APFs (except the APFs for the 1,3-Butadiene Standard).
    The Agency developed the proposed APFs after thoroughly reviewing 
the available literature, including chamber simulation studies and 
workplace protection factor studies. The proposed APFs would provide 
employers with critical information to use when selecting respirators 
for employees exposed to atmospheric contaminants found in general 
industry, construction, shipyard, longshoring, and marine terminal 
workplaces. Proper respirator selection using APFs is an important 
component of an effective respirator protection program. Accordingly, 
OSHA has made a preliminary conclusion that the proposed APFs are 
necessary to protect employees who use respirators against atmospheric 
contaminants.

DATES: Written comments. The Agency invites interested parties to 
submit written comments regarding the proposed rule, including comments 
to the information-collection determination under the Supplementary 
Information section of this Federal Register notice, by mail, 
facsimile, or electronically. You must send all comments, whether 
submitted by mail, facsimile, or electronically through OSHA's Web 
site, by September 4, 2003.
    Informal public hearings. The Agency plans to hold an informal 
public hearing in Washington, DC in late summer or early fall of 2003. 
OSHA expects the DC hearing to last from 9:30 a.m. to 5:30 p.m. on the 
first day, and from 8:30 a.m. to 5:30 p.m. on subsequent days; however, 
the exact daily schedule is at the discretion of the presiding 
administrative law judge. If an additional hearing is held, the Agency 
will announce the date, time, and location of this hearing later in the 
subsequent Federal Register notice.
    Notice of intention to appear to provide testimony at the informal 
public hearing. Interested parties who intend to present testimony at 
the informal public hearing in Washington, DC, must notify OSHA of 
their intention to do so no later than September 4, 2003.
    Hearing testimony and documentary evidence. Interested parties who 
will be requesting more than 10 minutes to present their testimony, or 
who will be submitting documentary evidence at the hearing, must 
provide the Agency with copies of their full testimony and all 
documentary evidence they plan to present by September 4, 2003.

ADDRESSES: Written comments. You may submit three copies of written 
comments to the Docket Office, Docket No. H049C, Technical Data Center, 
Room N-2625, OSHA, U.S. Department of Labor, 200 Constitution Ave., 
NW., Washington, DC 20210; telephone (202) 693-2350. If your written 
comments are 10 pages or fewer, you may fax them to the OSHA Docket 
Office, telephone number (202) 693-1648. You do not have to send OSHA a 
hard copy of your faxed comments. You may submit comments 
electronically through OSHA's Home page at http://ecomments.osha.gov/. 
If you would like to submit additional studies or journal articles, you 
must submit three copies of them to the OSHA Docket Office at the 
address above. These materials must clearly identify your electronic 
comments by name, date, subject, and docket number so we can attach 
them to your comments.
    Informal public hearings. The informal public hearing to be held in 
Washington, DC will be located in the Auditorium on the plaza level of 
the Frances Perkins Building, U.S. Department of Labor, 200 
Constitution Ave., NW., Washington, DC.
    Notice of intention to appear to provide testimony at the informal 
public hearing. Notices of intention to appear at the informal public 
hearing should be submitted in triplicate to the Docket Office, Docket 
No. H049C, Room N-2625, OSHA, U.S. Department of Labor, 200 
Constitution Avenue, NW., Washington, DC 20210. Notices may also be 
faxed to the Docket Office at (202) 693-1648 or submitted 
electronically at http://ecomments.osha.gov. OSHA Docket Office and 
Department of Labor hours of operation are 8:15 a.m. to 4:45 p.m.
    Hearing testimony and documentary evidence. Interested parties who 
will be requesting more than 10 minutes to present their testimony, or 
who will be submitting documentary evidence at the informal public 
hearing must mail three copies of the testimony and the documentary 
evidence to the Docket Office, Docket No. H049C, Room N-2625, OSHA, 
U.S. Department of Labor, 200 Constitution Avenue, NW., Washington DC 
20210. Additional information for submitting testimony and evidence is 
found under SUPPLEMENTARY INFORMATION.

FOR FURTHER INFORMATION CONTACT: For technical inquiries, contact Mr. 
John E. Steelnack, Directorate of Standards and Guidance, Room N-3718, 
OSHA, U.S. Department of Labor, 200 Constitution Ave., NW., Washington, 
DC 20210; telephone (202) 693-2289 or fax (202) 693-1678. For hearing 
information contact Ms. Veneta Chatmon, OSHA Office of Information, 
Docket No. H-49C, Room N-3649, U.S. Department of Labor, 200 
Constitution Ave., NW., Washington, DC 20210 (telephone (202) 693-
1999). For additional copies of this Federal Register notice, contact 
the Office of Publications, Room N-3103, OSHA, U.S. Department of 
Labor, 200 Constitution Ave., NW., Washington, DC 20210 (telephone 
(202) 693-1888). Electronic copies of this Federal Register notice, as 
well as news releases and other relevant documents, are available at 
OSHA's Home page at http://www.osha.gov.

SUPPLEMENTARY INFORMATION: 

OMB Review Under the Paperwork Reduction Act

    After a thorough analysis of the proposed provisions, OSHA believes 
that these provisions would not add to the existing collection-of-
information (i.e., paperwork) requirements regarding respirator 
selection. OSHA determined that its existing Respiratory Protection 
Standard at 29 CFR 1910.134 has two provisions that involve APFs and 
also impose paperwork requirements on employers. These provisions 
require employers to: Include respirator selection in their written 
respiratory protection program (29 CFR 1910.134(c)(1)(i)); and inform 
employees regarding proper respirator selection (29 CFR 1910.(k)(ii)). 
The information on respirator selection addressed by these two 
provisions must include a brief discussion of the purpose of APFs, and 
how to use them in selecting a respirator that affords an employee 
protection from airborne contaminants. The burden imposed by this 
requirement remains the same

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whether employers currently use the APFs published in the 1987 NIOSH 
RDL or the ANSI Z88.2-1992 Respiratory Protection Standard, or 
implement the APFs proposed in this rulemaking. Therefore, the proposed 
use of APFs in the context of these two existing respirator-selection 
provisions does not require an additional paperwork-burden 
determination because OSHA already accounted for this burden under its 
existing Respiratory Protection Standard (see 63 FR 1152-1154; OMB 
Control Number 1218-0099).
    Both OSHA's existing Respiratory Protection Standard and the 
proposed APF provisions require employers to use APFs as part of the 
respirator-selection process. This process includes obtaining 
information about the workplace exposure level to an airborne 
contaminant, identifying the exposure limit (e.g., permissible exposure 
limit) for the contaminant, using this information to calculate the 
required level of protection (i.e., the APF), and referring to an APF 
table to determine which respirator to select. Admittedly, this process 
involves the collection and use of information, but it does not require 
employers to inform others, either orally or in writing, about the 
process they use to select respirators for individual employees, or the 
outcomes of this process; by not requiring employers to communicate 
this information to others, OSHA removed this process from the ambit of 
the Paperwork Reduction Act of 1995 (PRA-95) (44 U.S.C. 3506(c)(2)(A)). 
In the alternative, even if PRA-95 applies, the proposal involves the 
same information-collection and -use requirements with regard to APFs 
as the existing standard (see paragraphs (d)(1) and (d)(3)(i) of 29 CFR 
1910.134, and the rationale for the existing APF requirements in the 
preamble to the final Respiratory Protection Standard, 63 FR 1163 and 
1203-1204); accordingly, the paperwork burden imposed by the proposal 
would be equivalent to the burden already imposed under the existing 
standard.
    Interested parties who want to comment on OSHA's determination that 
the proposed provisions contain no additional paperwork burden compared 
to the existing paperwork requirements must send their written comments 
to the Office of Information and Regulatory Affairs, Attn: OMB Desk 
Officer for OSHA, Office of Management and Budget, Room 10235, 725 17th 
Street NW., Washington, DC 20503. The Agency also encourages commenters 
to submit their comments on this paperwork determination to OSHA along 
with their other comments.

Federalism

    The Agency reviewed the proposed APF provisions according to the 
most recent Executive Order on Federalism (Executive Order 13132, 64 FR 
43225, August 10, 1999). This Executive Order requires that federal 
agencies, to the extent possible, refrain from limiting state policy 
options, consult with states before taking actions that restrict their 
policy options, and take such actions only when clear constitutional 
authority exists and the problem is of national scope. The Executive 
Order allows federal agencies to preempt state law only with the 
expressed consent of Congress; in such cases, federal agencies must 
limit preemption of state law to the extent possible.
    Under section 18 of the Occupational Safety and Health Act (the 
``Act'' or ``OSH Act''), Congress expressly provides OSHA with 
authority to preempt state occupational safety and health standards to 
the extent that the Agency promulgates a federal standard under section 
6 of the Act. Accordingly, section 18 of the Act authorizes the Agency 
to preempt state promulgation and enforcement of requirements dealing 
with occupational safety and health issues covered by OSHA standards 
unless the state has an OSHA-approved occupational safety and health 
plan (i.e., is a state-plan state) [see Gade v. National Solid Wastes 
Management Association, 112 S. Ct. 2374 (1992)]. Therefore, with 
respect to states that do not have OSHA-approved plans, the Agency 
concludes that this proposal conforms to the preemption provisions of 
the Act. Additionally, section 18 of the Act prohibits states without 
approved plans from issuing citations for violations of OSHA standards; 
the Agency finds that the proposed rulemaking does not expand this 
limitation.
    OSHA asserts that it has authority under Executive Order 13132 to 
propose APF requirements because the problems addressed by these 
requirements are national in scope. As noted in section VI (``Summary 
of the Preliminary Economic Analysis and Initial Regulatory Flexibility 
Analysis'') of this preamble, hundreds of thousands of employers must 
select appropriate respirators for millions of employees. These 
employees are exposed to many different types and levels of airborne 
contaminants found in general industry, construction, shipyard, 
longshoring, and marine terminal workplaces. Accordingly, the proposed 
requirements would provide employers in every state with critical 
information to use when selecting respirators to protect their 
employees from the risks of exposure to airborne contaminants. However, 
while OSHA drafted the proposed APF and MUC requirements to protect 
employees in every state, section 18(c)(2) of the Act permits state-
plan states to develop their own requirements to deal with any special 
workplace problems or conditions, provided these requirements are at 
least as effective as the final requirements that result from this 
proposal.

State Plans

    The 26 states and territories with their own OSHA-approved 
occupational safety and health plans must adopt comparable provisions 
within six months after the Agency publishes the final APF and MUC 
requirements. These states and territories are: Alaska, Arizona, 
California, Hawaii, Indiana, Iowa, Kentucky, Maryland, Michigan, 
Minnesota, Nevada, New Mexico, North Carolina, Oregon, Puerto Rico, 
South Carolina, Tennessee, Utah, Vermont, Virginia, Virgin Islands, 
Washington, and Wyoming. Connecticut, New Jersey and New York have OSHA 
approved State Plans that apply to state and local government employees 
only. Until a state-plan state promulgates its own comparable 
provisions, Federal OSHA will provide the state with interim 
enforcement assistance, as appropriate.

Unfunded Mandates

    The Agency reviewed the proposed APF and MUC provisions according 
to the Unfunded Mandates Reform Act of 1995 (UMRA) (2 U.S.C. 1501 et 
seq.) and Executive Order 12875. As discussed in section VI (``Summary 
of the Preliminary Economic Analysis and Initial Regulatory Flexibility 
Analysis'') of this preamble, OSHA estimates that compliance with this 
proposal would require private-sector employers to expend about $4.5 
million each year. However, while this proposal establishes a federal 
mandate in the private sector, it is not a significant regulatory 
action within the meaning of section 202 of the UMRA (2 U.S.C. 1532).
    OSHA standards do not apply to state and local governments, except 
in states that have voluntarily elected to adopt an OSHA-approved state 
occupational safety and health plan. Consequently, the proposed 
provisions do not meet the definition of a ``Federal intergovernmental 
mandate'' [see section 421(5) of the UMRA (2 U.S.C. 658(5)]. Therefore, 
based on a review of the rulemaking record to date, the Agency believes 
that few, if any, of the affected employers are state, local, and 
tribal governments. Therefore, the

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proposed APF requirements do not impose unfunded mandates on state, 
local, and tribal governments.

Protecting Children From Environmental Health and Safety Risks

    Executive Order 13045 requires that Federal agencies submitting 
covered regulatory actions to OMB's Office of Information and 
Regulatory Affairs (OIRA) for review pursuant to Executive Order 12866 
must provide OIRA with (1) an evaluation of the environmental health or 
safety effects that the planned regulation may have on children, and 
(2) an explanation of why the planned regulation is preferable to other 
potentially effective and reasonably feasible alternatives considered 
by the agency. Executive Order 13045 defines ``covered regulatory 
actions'' as rules that may (1) be economically significant under 
Executive Order 12866 (i.e., a rulemaking that has an annual affect on 
the economy of $100 million or more, or would adversely affect in a 
material way the economy, a sector of the economy, productivity, 
competition, jobs, the environment, public health or safety, or state, 
local, or tribal governments or communities), and (2) concern an 
environmental health risk or safety risk that an agency has reason to 
believe may disproportionately affect children. In this context, the 
term ``environmental health risks and safety risks'' means risks to 
health or safety that are attributable to products or substances that 
children are likely to come in contact with or ingest (e.g., through 
air, food, water, soil, product use).
    The proposed provisions are not economically significant under 
Executive Order 12866 (see section VI (``Summary of the Preliminary 
Economic Analysis and Initial Regulatory Flexibility Analysis'') of 
this preamble). In addition, after reviewing the proposed APF 
provisions, OSHA has determined that these provisions do not impose 
environmental health or safety risks to children as set forth in 
Executive Order 13045. The proposed provisions would require employers 
to use APFs in selecting proper respirators for employee use, with the 
objective of limiting employee exposures to airborne contaminants. To 
the best of OSHA's knowledge, no employees under 18 years of age work 
under conditions that require respirator use. However, if such 
conditions exist, children who use respirators selected according to 
these proposed provisions would receive adequate protection from the 
airborne contaminants. In this regard, the Agency is requesting public 
comment on whether employees under the age of 18 years use respirators, 
and, if they do, the extent to which the respirators provide them with 
adequate protection. Based on this discussion, OSHA believes that the 
APF and MUC requirements proposed in this rulemaking do not constitute 
a covered regulatory action as defined by Executive Order 13045.

Applicability of Existing Consensus Standards

    Section 6(b)(8) of the OSH Act requires OSHA to explain ``why a 
rule promulgated by the Secretary differs substantially from an 
existing national consensus standard,'' by publishing ``a statement of 
the reasons why the rule as adopted will better effectuate the purposes 
of the Act than the national consensus standard.'' [see 29 U.S.C. 
655(b)(8)]. Accordingly, the Agency compared the proposed APF 
requirements with the APF provisions of ANSI Z88.2-1992 (``Respiratory 
Protection''). This consensus standard, published by the American 
National Standards Institute in 1992, is the only publicly available 
consensus standard that includes APFs. In most instances, the APFs 
being proposed by the Agency are identical to ANSI's APFs, however, 
some differences exist. Where OSHA has proposed an APF that differs 
from ANSI's, the Summary and Explanation provides the basis for that 
decision.

Environmental Impact Assessment

    The Agency reviewed the proposed provisions according to the 
National Environmental Policy Act (NEPA) of 1969 (42 U.S.C. 4321 et 
seq.), the regulations of the Council of Environmental Quality (40 CFR 
part 1500), and the Department of Labor's NEPA procedures (29 CFR part 
11). OSHA estimates that this proposed rule would have a direct impact 
on a relatively small number of respirator users and, in so doing , 
merely alter the type of respirator they are using. The Agency does not 
anticipate that this will significantly alter solid waste patterns, 
water quality, or ambient air quality. As a result of this review, OSHA 
concludes that the proposed provisions would have no significant 
environmental impact.

I. General

Table of Contents

    The following Table of Contents identifies the major preamble 
sections of this proposal and the order in which they are presented:

Introductory Material
    Notice and Comment
    Dates for Hearings
Supplementary Information
    OMB Review Under the Paperwork Reduction Act
    Federalism
    State Plans
    Unfunded Mandates
    Protecting Children from Environmental Health and Safety Risks
    Applicability of Existing Consensus Standards
    Environmental Impact Assessment
I. General
    Table of contents
    Glossary
II. Pertinent Legal Authority
III. Events Leading to the Proposed Standard
    A. Regulatory History
    B. Need for Assigned Protection Factors
    C. Review of the Proposed Standard by the Advisory Committee for 
Construction Safety and Health (ACCSH)
IV. Methodology for Developing Assigned Protection Factors
    A. Dr. Nicas' Proposal and Response from Commenters
    B. Analyses of WPF Studies
    C. Analyses of SWPF Studies
    D. OSHA's Overall Summary Conclusions
    E. Summaries of Studies
V. Health Effects
VI. Summary of the Preliminary Economic Analysis and Initial 
Regulatory Flexibility Screening Analysis
VII. Summary and Explanation of the Proposed Standard
    A. Revisions to the Respiratory Protection Standard
    B. Superseding the Respirator Selection Provisions of Substance-
Specific Standards in Parts 1910, 1915, and 1926
VIII. Issues
IX. Public Participation--Comments and Hearings
X. Proposed Amendments to Standards

Glossary

    This glossary specifies the terms represented by acronyms, and 
provides definitions of other terms, used frequently in this proposal. 
This glossary does not change the legal requirements as proposed in 
this notice of proposed rulemaking, nor is it intended to propose new 
regulatory requirements or definitions. It is presented simply to 
assist the reader.
A. Acronyms
ACGIH: American Conference of Governmental Industrial Hygienists.
AIHA: American Industrial Hygiene Association.
ANSI: American National Standards Institute.
APF: Assigned Protection Factor (see definition in proposed regulatory 
text).
DOP: Dioctylphthalate (an aerosolized agent used for quantitative fit 
testing).
DFM: Dust/Fume/Mist filter.
EPF: Effective Protection Factor (see definition below under 
``Protection factor study'').
HEPA: High efficiency particulate air [filter] (see definition below).
IDLH: Immediately dangerous to life or health (see definition below).

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LANL: Los Alamos National Laboratory.
LLNL: Lawrence Livermore National Laboratory.
MSHA: Mine Safety and Health Administration.
MUC: Maximum Use Concentration (see definition in proposed regulatory 
text).
NIOSH: National Institute for Occupational Safety and Health.
NRC: Nuclear Regulatory Commission.
OSHA: Occupational Health and Safety Administration.
PAPR: Powered air-purifying respirator (see definition below).
PEL: Permissible Exposure Limit (an occupational exposure level 
specified by OSHA).
PPF: Program Protection Factor (see definition below under ``Protection 
factor study'').
QLFT: Qualitative fit test (see definition below).
QNFT: Quantitative fit test (see definition below).
RDL: Respirator Decision Logic (respirator selection guidance developed 
by NIOSH that contains a set of respirator protection factors).
REL: Recommended Exposure Limit (an occupational exposure level 
recommended by NIOSH).
SAR: Supplied-air respirator (see definition below).
SCBA: Self-contained breathing apparatus (see definition below).
WPF: Workplace Protection Factor (see definition below under 
``Protection factor study'').
TLV: Threshold Limit Value (an occupational exposure level recommended 
by ACGIH).
SWPF: Simulated Workplace Protection Factor (see definition below under 
``Protection factor study'').
B. Definitions
    Terms followed by an asterisk (*) refer to definitions that can be 
found in paragraph (b) (``Definitions'') of OSHA's Respiratory 
Protection Standard (29 CFR 1910.134).
    Air-purifying respirator*: A respirator with an air-purifying 
filter, cartridge, or canister that removes specific air contaminants 
by passing ambient air through the air-purifying element.
    Atmosphere-supplying respirator*: A respirator that supplies the 
respirator user with breathing air from a source independent of the 
ambient atmosphere, and includes SARs and SCBA units.
    Canister or cartridge*: A container with a filter, sorbent, or 
catalyst, or combination of these items, which removes specific 
contaminants from the air passed through the container.
    Continuous flow respirator : An atmosphere-supplying respirator 
that provides a continuous flow of breathable air to the respirator 
facepiece.
    Demand respirator*: An atmosphere-supplying respirator that admits 
breathing air to the facepiece only when a negative pressure is created 
inside the facepiece by inhalation.
    Filter or air-purifying element*: A component used in respirators 
to remove solid or liquid aerosols from the inspired air.
    Filtering facepiece (or dust mask)*: A negative pressure 
particulate respirator with a filter as an integral part of the 
facepiece or with the entire facepiece composed of the filtering 
medium.
    Fit factor*: A quantitative estimate of the fit of a particular 
respirator to a specific individual, and typically estimates the ratio 
of the concentration of a substance in ambient air to its concentration 
inside the respirator when worn.
    Fit test*: The use of a protocol to qualitatively or quantitatively 
evaluate the fit of a respirator on an individual.
    Helmet*: A rigid respiratory inlet covering that also provides head 
protection against impact and penetration.
    High-efficiency particulate air filter*: A filter that is at least 
99.97% efficient in removing monodisperse particles of 0.3 micrometers 
in diameter. The equivalent NIOSH 42 CFR 84 particulate filters are the 
N100, R100, and P100 filters.
    Hood*: A respiratory inlet covering that completely covers the head 
and neck and may also cover portions of the shoulders and torso.
    Immediately dangerous to life or health*: An atmosphere that poses 
an immediate threat to life, would cause irreversible adverse health 
effects, or would impair an individual's ability to escape from a 
dangerous atmosphere.
    Loose-fitting facepiece*: A respiratory inlet covering that is 
designed to form a partial seal with the face.
    Negative pressure respirator (tight-fitting)*: A respirator in 
which the air pressure inside the facepiece is negative during 
inhalation with respect to the ambient air pressure outside the 
respirator.
    Positive pressure respirator*: A respirator in which the pressure 
inside the respiratory inlet covering exceeds the ambient air pressure 
outside the respirator.
    Powered air-purifying respirator*: An air-purifying respirator that 
uses a blower to force the ambient air through air-purifying elements 
to the inlet covering.
    Pressure demand respirator*: A positive pressure atmosphere-
supplying respirator that admits breathing air to the facepiece when 
the positive pressure is reduced inside the facepiece by inhalation.
    Protection factor study: A study that determines the protection 
provided by a respirator during use. This determination is generally 
accomplished by measuring the ratio of the concentration of an agent 
(e.g., hazardous substance) outside the respirator (Co) to the agent's 
concentration inside the respirator (Ci) (i.e., Co/Ci). Therefore, as 
the ratio between Co and Ci increases, the protection factor increases, 
indicating an increase in the level of protection provided to employees 
by the respirator. Four types of protection factor studies are:
    Effective Protection Factor (EPF) study--a study, conducted in the 
workplace, that measures the protection provided by a properly 
selected, fit-tested, and functioning respirator when used 
intermittently for only some fraction of the total workplace exposure 
time (i.e., sampling is conducted during periods when respirators are 
worn and not worn). EPFs are not directly comparable to WPF values 
because the determinations include both the time spent in contaminated 
atmospheres with and without respiratory protection; therefore, EPFs 
tend to understate the protection that would be obtained if the 
respirator were being worn at all times.
    Program Protection Factor (PPF) study--a study that estimates the 
protection provided by a respirator within a specific respirator 
program. Like the EPF, it is focused not only on the respirator's 
performance, but also the effectiveness of the complete respirator 
program. PPFs are affected by all factors of the program, including 
respirator selection and maintenance, user training and motivation, 
work activities, and program administration.
    Workplace Protection Factor (WPF) study--a study, conducted under 
actual conditions of use in the workplace, that measures the protection 
provided by a properly selected, fit-tested, and functioning 
respirator, when the respirator is correctly worn and used as part of a 
comprehensive respirator program. Measurements of Co and Ci are 
obtained only while the respirator is being worn during performance of 
normal work tasks (i.e., samples are not collected when the respirator 
is not being worn). As the degree of protection afforded by the 
respirator increases, the WPF increases.
    Simulated Workplace Protection Factor (SWPF) study--a study, 
conducted in a controlled laboratory setting and in which Co and Ci

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sampling is performed while the subject performs a series of set 
exercises. The laboratory setting is used to control many of the 
variables found in workplace studies, while the exercises simulate the 
work activities of respirator users. This type of study is designed to 
determine the optimum performance of respirators by reducing the impact 
of sources of variability through maintenance of tightly controlled 
study conditions.
    Qualitative fit test*: A pass/fail fit test to assess the adequacy 
of respirator fit that relies on the individual's response to the test 
agent.
    Quantitative fit test*: An assessment of the adequacy of respirator 
fit by numerically measuring the amount of leakage into the respirator.
    Self-contained breathing apparatus*: An atmosphere-supplying 
respirator for which the breathing air source is designed to be carried 
by the user.
    Supplied-air respirator (or airline) respirator*: An atmosphere-
supplying respirator for which the source of breathing air is not 
designed to be carried by the user.
    Tight-fitting facepiece*: A respiratory inlet covering that forms a 
complete seal with the face.

II. Pertinent Legal Authority

    The purpose of the Occupational Safety and Health Act, 29 U.S.C. 
651 et seq. (the ``OSHA Act'' or ``Act'') is to ``assure so far as 
possible every working man and woman in the Nation safe and healthful 
working conditions and to preserve our human resources.'' [29 U.S.C. 
651(b)]. To achieve this goal, Congress authorized the Secretary of 
Labor to promulgate and enforce occupational safety and health 
standards [see 29 U.S.C. 654(b) (requiring employers to comply with 
OSHA standards), 29 U.S.C. 655(a) (authorizing summary adoption of 
existing consensus and federal standards within two years of the Act's 
enactment), and 29 U.S.C. 655(b) (authorizing promulgation of standards 
pursuant to notice and comment)].
    A safety or health standard is a standard ``which requires 
conditions, or the adoption or use of one or more practices, means, 
methods, operations, or processes, reasonably necessary or appropriate 
to provide safe or healthful employment or places of employment.'' [29 
U.S.C. 652(8)]. A standard is reasonably necessary or appropriate 
within the meaning of section 652(8) of the Act when it substantially 
reduces or eliminates significant risk, and is technologically and 
economically feasible, cost effective, consistent with prior Agency 
action or supported by a reasoned justification for departing from 
prior Agency action, and supported by substantial evidence; it must 
also effectuate the Act's purposes better than any national consensus 
standard it supersedes [see International Union, UAW v. OSHA (LOTO II), 
37 F.3d 665 (DC Cir. 1994; and 58 FR 16612-16616 (March 30, 1993)].
    OSHA has discussed the nature of adverse health effects caused by 
exposure to airborne chemical hazards many times in previous rulemaking 
activities [see, for example, the preambles to any of OSHA's substance-
specific standards codified in 29 CFR 1910.1001 to 1910.1052]. As 
discussed in the Significance of Risk section of the Respiratory 
Protection Standard, the health risk presented to workers can be 
represented by the risk that a respirator will not be properly selected 
or used, which increases the possibility that the user will be 
overexposed to a harmful air contaminant. The risks that are addressed 
by the Respiratory Protection Standard are not characterized as 
illness-specific risks but, instead, relate to a more general 
probability that when a respirator provides insufficient protection, 
the wearer may be exposed to a level of air contaminant that is 
associated with material impairment of the worker's health.
    The Agency believes that a standard is technologically feasible 
when the protective measures it requires already exist, can be brought 
into existence with available technology, or can be created with 
technology that can reasonably be expected to be developed [see 
American Textile Mfrs. Institute v. OSHA (Cotton Dust), 452 U.S. 490, 
513 (1981); American Iron and Steel Institute v. OSHA (Lead II), 939 
F.2d 975, 980 (DC Cir. 1991)]. A standard is economically feasible when 
industry can absorb or pass on the costs of compliance without 
threatening the industry's long-term profitability or competitive 
structure [see Cotton Dust, 452 U.S. at 530 n. 55; Lead II, 939 F.2d at 
980], and a standard is cost effective when the protective measures it 
requires are the least costly of the available alternatives that 
achieve the same level of protection [see Cotton Dust, 453 U.S. at 514 
n. 32; International Union, UAW v. OSHA (LOTO III), 37 F.3d 665, 668 
(DC Cir. 1994)].
    All standards must be highly protective [see 58 FR 16612, 16614-15 
(March 30, 1993); LOTO III, 37 F.3d at 669]. Accordingly, section 
8(g)(2) of the Act authorizes OSHA ``to prescribe such rules and 
regulations as [it] may deem necessary to carry out its 
responsibilities under the Act'' [see 29 U.S.C. 657(g)(2)]. However, 
health standards must also meet the ``feasibility mandate'' of section 
6(b)(5) of the OSH Act, 29 U.S.C. 655(b)(5). Section 6(b)(5) of the Act 
requires OSHA to select ``the most protective standard consistent with 
feasibility'' needed to reduce significant risk when regulating health 
hazards [see Cotton Dust, 452 U.S. at 509]. Section 6(b)(5) also 
directs OSHA to base health standards on ``the best available 
evidence,'' including research, demonstrations, and experiments [see 29 
U.S.C. 655(b)(5)]. In this regard, OSHA must consider ``in addition to 
the attainment of the highest degree of health and safety protection * 
* * the latest scientific data * * * feasibility and experience gained 
under this and other health and safety laws.'' (Id.). Furthermore, 
section 6(b)(5) of the Act specifies that standards must ``be expressed 
in terms of objective criteria and of the performance desired'' [see 29 
U.S.C. 655(b)(7)].
    The proposed APF and MUC provisions are integral components of an 
effective respiratory protection program. Respiratory protection is a 
supplemental method used by employers to protect employees against 
airborne contaminants in workplaces where feasible engineering controls 
and work practices are not available, have not yet been implemented, or 
are not in themselves sufficient to protect employee health. Employers 
also use respiratory protection under emergency conditions involving 
the accidental release of airborne contaminants. The proposed 
amendments to OSHA's Respiratory Protection Standard, and the Agency's 
substance-specific standards, would provide employers with critical 
information to use when selecting respirators for employees exposed to 
airborne contaminants found in general industry, construction, 
shipyard, longshoring, and marine terminal workplaces. Since it is 
generally recognized that different types of respiratory protective 
equipment provide different degrees of protection against hazardous 
exposures, proper respirator selection is of critical importance. The 
proposed APF and MUC provisions provide additional guidance on the 
point at which an increase in the level of respiratory protection is 
necessary. The APF and MUC provisions will greatly enhance an 
employer's ability to select a respirator that will adequately protect 
employees. OSHA believes that in the absence of these proposed 
provisions, employers will be less certain about which respirators to 
select for adequate employee protection.

[[Page 34041]]

    The Agency also developed the proposed provisions to be feasible 
and cost effective, and is specifying them in terms of objective 
criteria and the level of performance desired. In this regard, section 
VI (``Summary of the Preliminary Economic Analysis and Initial 
Regulatory Flexibility Analysis'') of this preamble provides the 
benefits and costs of this proposal, and describes several other 
alternatives as required by section 205 of the UMRA (2 U.S.C. 1535). 
Based on this information, OSHA preliminarily concludes that the 
proposed APF and MUC provisions constitute the most cost-effective 
alternative for meeting its statutory objective of reducing risk of 
adverse health effects to the extent feasible.

III. Events Leading to the Proposed Standard

A. Regulatory History

    Congress created the Occupational Safety and Health Administration 
(OSHA) in 1970, and gave it the responsibility for promulgating 
standards to protect the health and safety of American workers. As 
directed by the OSH Act, the Agency adopted existing Federal standards 
and national consensus standards developed by various organizations 
such as the American Conference of Governmental Industrial Hygienists 
(ACGIH), the National Fire Protection Association (NFPA), and the 
American National Standards Institute (ANSI). The ANSI standard Z88.2-
1969, ``Practices for Respiratory Protection,'' was the basis of the 
first six sections (permissible practice, minimal respirator program, 
selection of respirators, air quality, use, maintenance and care) of 
OSHA's Respiratory Protection Standard (29 CFR 1910.134) adopted in 
1971. The seventh section was a direct, complete incorporation of ANSI 
Standard K13.1-1969, ``Identification of Gas Mask Canisters.''
    The Agency promulgated an initial Respiratory Protection Standard 
for the construction industry (29 CFR 1926.103) in April 1971. On 
February 9, 1979, OSHA formally applied 29 CFR 1910.134 to the 
construction industry (44 FR 8577). Agencies that preceded OSHA 
developed the original maritime respiratory protection standards in the 
1960s (e.g., section 41 of the Longshore and Harbor Worker Compensation 
Act). The section designations adopted by OSHA for these standards, and 
their original promulgation dates, are: Shipyards--29 CFR 1915.82, 
February 20, 1960 (25 FR 1543); Marine Terminals--29 CFR 1917.82, March 
27, 1964 (29 FR 4052); and Longshoring--29 CFR 1918.102, February 20, 
1960 (25 FR 1565). OSHA incorporated 29 CFR 1910.134 by reference into 
its Marine Terminal standards (Part 1917) on July 5, 1983 (48 FR 
30909). The Agency updated and strengthened its Longshoring and Marine 
Terminal standards in 1996 and 2000, and these standards now 
incorporate 29 CFR 1910.134 by reference.
    Under the Respiratory Protection Standard that OSHA initially 
adopted, employers needed to follow the guidance of the Z88.2-1969 ANSI 
standard to ensure proper selection of respirators. Subsequently, OSHA 
published an Advance Notice of Proposed Rulemaking (``ANPR'') to revise 
the Respiratory Protection Standard on May 14, 1982 (47 FR 20803). Part 
of the impetus for this notice was the Agency's inclusion of new 
respirator requirements in the comprehensive substance-specific 
standards promulgated under Section (6)(b) of the OSH Act, e.g., fit 
testing protocols, respirator selection tables, use of PAPRs, changing 
filter elements whenever an employee detected an increase in breathing 
resistance, and requirements referring employees with breathing 
difficulties to a physician trained in pulmonary medicine, either at 
fit testing or during routine respirator use [see, e.g, 29 CFR 
1910.1025 (OSHA's Lead Standard)]. The respirator provisions in these 
substance-specific standards took into account advances in respirator 
technology and changes in related guidance documents that were state-
of-the-art when OSHA published these substance specific standards and, 
in particular, recognized that effective respirator use depends on a 
comprehensive respiratory protection program that includes use of APFs.
    OSHA's 1982 ANPR sought information on the effectiveness of its 
current Respiratory Protection Standard, the need to revise this 
standard, and suggestions on the nature of the revisions. The 1982 ANPR 
referenced the ANSI Z88.2-1980 standard on respiratory protection with 
its table of protection factors, the 1976 report by Dr. Ed Hyatt from 
the LASL titled ``Respiratory Protection Factors'' (Ex. 2), and the RDL 
developed jointly by OSHA and NIOSH, as revised in 1978 (Ex. 9, Docket 
No. H049). Questions 2, 3, and 4 in the 1982 
ANPR asked for comments on how OSHA should use protection factors. The 
Agency received responses from 81 interested parties. The commenters 
generally supported revising OSHA's Respiratory Protection Standard, 
and provided recommendations regarding approaches for including a table 
of protection factors (Ex. 15).
    On September 17, 1985, OSHA announced the availability of a 
preliminary draft of the proposed Respiratory Protection Standard. This 
preproposal draft standard included the public comments received in 
response to 1982 ANPR, and OSHA's own analysis of revisions needed in 
the Respiratory Protection Standard to account for state-of-the-art 
respiratory protection. The Agency received 56 responses from 
interested parties (Ex. 36) which OSHA carefully reviewed in developing 
the proposal.
    On November 15, 1994, OSHA published the proposed rule to revise 29 
CFR 1910.134, and provided public notice of an informal public hearing 
on the proposal (59 FR 58884). The Agency convened the informal public 
hearing on June 6, 1995. On June 15, 1995, as part of the public 
hearing, OSHA held a one-day panel discussion by respirator experts of 
APFs. Areas discussed included difficulties in measuring performance of 
respiratory protection in WPF and SWPF studies, statistical 
uncertainties regarding the distribution of data from these studies, 
and the problems associated with setting APFs for all respirators that 
protect all potential respirator users across a wide variety of 
workplaces and exposure conditions.
    OSHA reopened the rulemaking record for the revised Respiratory 
Protection Standard on November 7, 1995 (60 FR 56127), requesting 
comments on a study performed for OSHA by Dr. Mark Nicas titled ``The 
Analysis of Workplace Protection Factor Data and Derivation of Assigned 
Protection Factors' (Ex. 1-156). That study, which the Agency placed in 
the rulemaking docket on September 20, 1995, addressed the use of 
statistical modeling for determining respirator APFs. OSHA received 12 
comments on the Nicas report. This report, and the comments received in 
response to it, convinced OSHA that more information would be necessary 
before it could resolve the complex issues regarding how to establish 
APFs, including what methodology to use in analyzing existing 
protection factor studies (see Section IV below for a more detailed 
explanation of the Nicas report and the comments made on it).
    OSHA published the final, revised Respiratory Protection Standard, 
29 CFR 1910.134, on January 8, 1998 (63 FR 1152). The standard contains 
worksite-specific requirements for program administration, procedures 
for respirator selection, employee training, fit testing, medical 
evaluation, respirator

[[Page 34042]]

use, and other provisions. However, OSHA reserved the sections of the 
final standard related to APFs and maximum use concentration (MUC) 
pending further rulemaking (see 63 FR 1182 and 1203). The Agency stated 
that, until a future rulemaking on APFs is completed:

    [Employers must] take the best available information into 
account in selecting respirators. As it did under the previous 
[Respiratory Protection] standard, OSHA itself will continue to 
refer to the [APFs in the 1987 NIOSH RDL] in cases where it has not 
made a different determination in a substance specific standard. 
(see 63 FR 1163)

    The Agency subsequently established a separate docket (i.e., H049C) 
for the APF rulemaking. This docket includes copies of material related 
to APFs that it previously placed in the docket (H049) for the revised 
Respiratory Protection Standard. The APF rulemaking docket also 
contains other APF-related materials, studies, and data that OSHA 
obtained after it promulgated the final Respiratory Protection Standard 
in 1998.
History of Assigned Protection Factors
    In 1965, the Bureau of Mines published ``Respirator Approval 
Schedule 21B,'' which contained the term ``protection factor'' as part 
of its approval process for half-mask respirators (for protection up to 
10 times the TLV) and full facepiece respirators (for protection up to 
100 times the TLV). The Bureau of Mines based these protection factors 
on quantitative fit tests, using dioctyl pthalate (DOP), that were 
conducted on six male test subjects performing simulated work 
exercises.
    The Atomic Energy Commission (AEC) published proposed protection 
factors for respirators in 1967, but later withdrew them because 
quantitative fit testing studies were available for some, but not all, 
types of respirators. To address this shortcoming, the AEC subsequently 
sponsored respirator studies at LASL, starting in 1969.
    ANSI standard Z88.2-1969, which OSHA adopted by reference in 1971, 
did not contain APFs for respirator selection. Nevertheless, this ANSI 
standard recommended that ``due consideration be given to potential 
inward leakage in selecting devices,'' and contained a list of the 
various respirators grouped according to the quantity of leakage into 
the facepiece expected during routine use.
    In 1972, NIOSH and the Bureau of Mines published new approval 
schedules for respiratory protection under 30 CFR Part 11. However, 
these new approval schedules did not include fit testing provisions as 
part of the respirator certification process.
    NIOSH sponsored additional respirator studies at LASL, beginning in 
1971, that used quantitative test systems to measure the overall 
performance of respirators. Dr. Edwin C. Hyatt of LASL included a table 
of protection factors for, single-use dust respirators; quarter-mask, 
half-mask, and full facepiece air-purifying respirators; and SCBAs in a 
1976 report titled ``Respirator Protection Factors'' (Ex. 2). The 
protection factors were based on data from DOP and sodium chloride 
quantitative fit test studies performed on these respirators at LASL 
between 1970 and 1973. The table also contained recommended protection 
factors for respirators that had no performance test data. Dr. Hyatt 
based these recommended protection factors on the judgment and 
experience of LASL researchers, as well as extrapolations from 
available facepiece leakage data for similar respirators. For example, 
he assumed that performance data for SCBAs operated in the pressure 
demand mode could be used to represent other (non-tested) respirators 
that maintain positive pressure in the facepiece, hood, helmet, or suit 
during inhalation. In addition, he recommended in his report that NIOSH 
continue testing the performance of respirators that lacked adequate 
fit test data. Relative to this, staff members at LASL (from 1974 to 
1978) used a representative 35-person test panel to conduct 
quantitative fit tests on all air-purifying particulate respirators 
approved by the Bureau of Mines and NIOSH.
    In August 1975, the Joint NIOSH-OSHA Standards Completion Program 
published the RDL (Ex. 25-4, Appendix F, Docket No. H049). The RDL 
contained a table of protection factors that were based on quantitative 
fit testing performed at LASL and elsewhere, as well as the expert 
judgment of the RDL authors. The 1978 NIOSH update of the RDL contained 
the following protection factors:
    5 for single-use respirators;
    10 for half-mask respirators with DFM or HEPA filters;
    50 for full facepiece air-purifying respirators with HEPA filters 
or chemical cartridges;
    1,000 for PAPRs with HEPA filters;
    1,000 for half-mask SARs operated in the pressure demand mode;
    2,000 for full facepiece SARs operated in the pressure demand mode; 
and
    10,000 for full facepiece SCBAs operated in the pressure demand 
mode.
    ANSI's respiratory protection Subcommittee decided to revise Z88.2-
1969 in the late 1970s. During its deliberations, the Subcommittee 
conducted an extensive discussion regarding the role of respirator 
protection factors in an effective respiratory protection program. As a 
result, the Subcommittee decided to add an APF table to the revised 
standard. In May 1980, ANSI published the revision as Z88.2-1980 (Ex. 
10, Docket No. H049) and it contained the first ANSI Z88.2 respiratory 
protection factor table. The ANSI Subcommittee based the table on 
Hyatt's protection factors, which it updated using results from fit 
testing studies performed at LANL and elsewhere since 1973. For 
example, the protection factor for full facepiece air-purifying 
particulate respirators was 100 when qualitatively fit tested, or 1,000 
when equipped with high efficiency filters and quantitatively fit 
tested. The table consistently gave higher protection factors to tight-
fitting facepiece respirators when employers performed quantitative fit 
testing rather than qualitative fit testing. The ANSI Subcommittee 
concluded that PAPRs (with any respiratory inlet covering), atmosphere-
supplied respirators (in continuous flow or pressure demand mode), and 
pressure demand SCBAs required no fit testing because they operated in 
a positive pressure mode. Accordingly, it gave these respirators high 
protection factors, limited only by IDLH values. The Subcommittee 
assigned protection factors of 10,000 and over to respirators used in 
IDLH atmospheres.
    In response to a complaint to NIOSH that the PAPRs used in a plant 
did not appear to provide the expected protection factor of 1,000, 
Myers and Peach of NIOSH conducted a WPF study during silica bagging 
operations. Myers and Peach tested half-mask and full facepiece PAPRs 
and found protection factors that ranged from 16 to 215. They published 
the results of the study in 1983 (Ex. 1-64-46). The results of this 
study led NIOSH and other researchers, as well as respirator 
manufacturers, to perform additional WPF studies on PAPRs and other 
respirators.
    NIOSH revised its RDL in 1987 (Ex. 1-54-437Q). While the revision 
retained many of the provisions of the 1978 RDL, it recognized the 
problems involved in developing APFs. The 1987 RDL also revised the 
APFs for some respirators, based on NIOSH's WPF studies. For example, 
the APFs were lowered for the following respirator classes: PAPRs with 
a loose-fitting hood or helmet to 25; PAPRs with a tight-fitting 
facepiece and a HEPA filter to 50; supplied-air continuous flow hoods 
or helmets to 25; and supplied-air continuous flow tight-fitting 
facepiece respirators to 50.

[[Page 34043]]

NIOSH stated that it may revise the 1987 RDL if warranted by subsequent 
WPF studies.
    In August 1992, ANSI again revised its Z88.2 Respiratory Protection 
Standard (Ex. 1-50). The ANSI Z88.2-1992 standard contained a revised 
APF table, based on the Z88.2 Subcommittee's review of the available 
protection factor studies. In a report describing the revised standard 
(Ex. 1-64-423), Nelson, Wilmes, and daRoza described the rationale used 
by the ANSI Subcommittee in setting APFs:

    If WPF studies were available, they formed the basis for the 
[APF] number assigned. If no such studies were available, then 
laboratory studies, design analogies, and other information was used 
to decide what value to place in the table. In all cases where the 
assigned protection factor changed when compared to the 1980 
standard, the assigned number is lower in the 1992 standard.

    In addition, the 1992 ANSI Z88.2 standard abandoned the 1980 
standard's practice of giving increased protection factors to some 
respirators if quantitative fit testing was performed.
    Tom Nelson, the co-chair of the ANSI Z88.2-1992 Subcommittee, 
published a second report, entitled ``The Assigned Protection Factor 
According to ANSI'' (Ex. 135), four years after the Z88.2 Subcommittee 
completed the revised 1992 standard. In the report, he reviewed the 
reasoning used by the ANSI Subcommittee in setting the 1992 ANSI APFs. 
He noted that the Z88.2 Subcommittee gave an APF of 10 to all half-mask 
air-purifying respirators, including quarter-mask, elastomeric, and 
disposable respirators. The Subcommittee also recommended that full 
facepiece air-purifying respirators retain an APF of 100 (from the 1980 
ANSI standard) because no new data were available to justify another 
value. The Z88.2 Subcommittee also reviewed the 1987 NIOSH RDL values, 
particularly the RDL's reduction of loose-fitting facepiece and PAPRs 
with helmets or hoods to an APF of 25 based on their performance in WPF 
studies. For half-mask PAPRs, the ANSI Subcommittee set an APF of 50 
based on a WPF study by Lenhart (Ex. 1-64-42). The ANSI Subcommittee 
had no WPF data available for full facepiece PAPRs, so it decided to 
select an APF of 1,000 to be consistent with the APF for PAPRs with 
helmets or hoods. The Subcommittee, in turn, based its APF of 1,000 for 
PAPRs with helmets or hoods on design analogies (i.e., same facepiece 
designs, operation at the same airflow rates) between these respirators 
and airline respirators. Nelson noted that a subsequent WPF report by 
Keys (Ex. 1-64-40) on PAPRs with helmets or hoods was consistent with 
an APF of 1,000. According to Nelson, the Subcommittee used WPF studies 
by Myers (Ex. 1-64-48), Gosselink (Ex. 1-64-23), Myers (Ex. 1-64-47), 
and Que Hee and Lawrence (Ex. 1-64-60) to set an APF of 25 for PAPRs 
with loose-fitting facepieces. Nelson stated that two WPF studies, 
conducted by Gaboury and Burd (Ex. 1-64-24) and Stokes (Ex. 1-64-66) 
subsequent to publication of ANSI Z88.2-1992, supported the APF of 25 
selected by the Subcommittee for PAPRs with loose-fitting facepieces.
    Tom Nelson stated in his report that the ANSI Subcommittee had no 
new information on atmosphere-supplying respirators. Therefore, the 
APFs for these respirators were based on analogies with other similarly 
designed respirators (Ex. 135). The ANSI Subcommittee based the APF of 
50 for half-mask continuous flow atmosphere-supplying respirators, and 
the APF of 25 for loose-fitting facepiece continuous flow atmosphere-
supplying respirators, on the similarities between these respirators 
and PAPRs with the same airflow rates. Nelson noted that the ANSI 
Subcommittee set the APF of 1,000 for full facepiece continuous flow 
atmosphere-supplying respirators to be consistent with the APF for SARs 
with helmets or hoods found in two earlier studies--a WPF study by 
Johnson (Ex. 1-64-36) and a SWPF study by Skaggs (Ex. 1-3803). The 
Subcommittee used the analogy between PAPRs and continuous flow 
supplied-air respirators to select the APF of 50 for half-mask pressure 
demand SARs and 1,000 for full facepiece pressure demand SARs. Nelson 
stated: ``The committee believed that setting a higher APF because of 
the pressure demand feature was not warranted, but rather that the 
total airflow was critical.''
    Nelson noted in the report that the Subcommittee selected no APF 
for SCBAs. In explaining the committee's decision, he stated that ``the 
performance of this type of respirator may not be as good as previously 
measured in quantitative fit test chambers.'' Nelson also observed that 
the ANSI 88.2-1992 standard justified this approach in a footnote to 
the APF table. The footnote states:

    A limited number of recent simulated workplace studies concluded 
that all users may not achieve protection factors of 10,000. Based 
on [these] limited data, a definitive assigned protection factor 
could not be listed for positive pressure SCBAs. For emergency 
planning purposes where hazardous concentrations can be estimated, 
an assigned protection factor of no higher than 10,000 should be 
used.

    A new ANSI Z88.2 Subcommittee currently is reviewing the ANSI 
Z88.2-1992 standard, in accordance with ANSI policy specifying that 
each standard receive a periodic review. This review likely will result 
in revisions to the Z88.2 APF table based on WPF and SWPF respirator 
performance studies conducted since publication of the current standard 
in 1992.

B. Need for APFs

    The proposed APF definition and regulatory text are important 
additions to, and an integral part of, OSHA's Respiratory Protection 
Standard because employers need this information to select appropriate 
respirators for employee use when engineering and work-practice 
controls are insufficient to maintain hazardous substances at safe 
levels in the workplace. Employers need the consistent and valid 
information contained in the proposed APF provisions to select 
respirators for employee protection, based on the type of hazardous 
substance and the level of employee exposure to that substance.
    As noted in Table I of the proposed regulatory text, the proposed 
APFs differ for each class of respirator. In this regard, the proposed 
APF for a class of respirators specifies the workplace level of 
protection that class of respirator should provide under an effective 
respiratory protection program. Therefore, when the concentration of a 
hazardous substance in the workplace is less than 10 times the PEL, the 
employer must select a respirator from a respirator class with an APF 
of at least 10 for use by employees exposed to that substance. However, 
when the concentration of the hazardous substance is greater than 10 
times the PEL, the employer must select a respirator that has an APF 
greater than 10 for this purpose. In addition, employers would derive 
MUCs from the APFs proposed for the different respirator classes. These 
MUCs determine the maximum atmospheric concentration of toxic gasses 
and vapors at which respirators equipped with cartridges and canisters 
can be used to protect employees.
    In summary, when used in conjunction with the existing provisions 
of the Respiratory Protection Standard, especially the respirator 
selection requirements specified in paragraph (d), the proposed APF 
definition and regulatory text would provide employers with the 
information they need to select the appropriate respirators for 
reducing employee exposures to hazardous substances to safe levels. 
Accordingly, integrating the proposed APF provisions into the 
Respiratory Protection Standard will

[[Page 34044]]

ensure that employees receive the optimum level of protection afforded 
by that standard.

C. Review of the Proposed Standard by the Advisory Committee for 
Construction Safety and Health (ACCSH)

    The proposed provisions would replace the existing respirator-
selection requirements specified by the Respiratory Protection Standard 
for the construction industry (29 CFR 1926.103). Accordingly, OSHA's 
regulation governing the Advisory Committee on Construction Safety and 
Health (ACCSH) at 29 CFR 1912.3 requires OSHA to consult with the ACCSH 
whenever the Agency proposes a rulemaking that involves the 
occupational safety and health of construction employees. On December 
5, 2002, OSHA briefed the ACCSH membership on the proposed provisions 
and responded to their questions. On March 27, 2003, the APF proposal 
was distributed to the ACCSH membership for their review prior to their 
next regular meeting on May 22, 2003. OSHA staff discussed the APF 
proposal and answered questions from the ACCSH members during their 
meeting on May 22, 2003. The ACCSH then recommended that OSHA proceed 
with publishing the proposal.

IV. Methodology for Developing Assigned Protection Factors

    This section contains an overview of the analyses performed for 
OSHA and summaries of the studies used in these analyses. OSHA entered 
the complete analyses and studies into Docket H049C as Exhibits 3, 4, 
and 5 and Exhibit 1-156 (Dr. Nicas' report). Studies and information 
supporting the APF for each class of respirator are discussed in 
Section VII of this document. The analyses discussed below assisted 
OSHA in determining its proposed approach to deriving APFs. Commenters 
expressed appreciation for the approach suggested by Dr. Nicas, but 
nearly all did not support implementation of his methods. However, his 
recommendations provided guidance to the Agency regarding the types of 
studies and data needed for determining APFs. Dr. Brown's complex 
statistical analyses demonstrated the widespread variability inherent 
in current workplace protection factor studies. However, he found in 
his final analysis that the performance of filtering facepiece and 
elastomeric half-mask respirators could not be differentiated, thereby 
supporting grouping of these two types of respirator under one APF.

A. Dr. Nicas' Proposal and Response From Commenters

    During the June 1995 APF hearings, OSHA devoted a full day to a 
panel discussion on the uncertainties associated with sample statistics 
and their use for deriving APFs. Based on this discussion, OSHA 
contracted with Dr. Mark Nicas to develop a statistical method for 
deriving APFs. Nicas used two approaches to account for within-wearer 
and between-wearer variabilities. For penetration data collected from a 
specific cohort of respirator wearers, he used a one-factor lognormal 
analysis of variance. He used a two-factor lognormal analysis of 
variance to perform a meta-analysis of the data from studies of 
different cohorts of respirator wearers. Using these approaches, Nicas 
proposed assigning two different protection factors; he recommended one 
for chronic toxicants (i.e., substances regulated by an 8-hour PEL), 
and the other for acute toxicants (i.e., substances regulated by a 
STEL). Nicas also made recommendations regarding sampling data 
management and inclusion of studies in statistical analyses of 
respirator performance.
    OSHA reopened the rulemaking record on November 7, 1995 (60 FR 
56127) to request comment on Dr. Nicas' report titled ``The Analysis of 
Workplace Protection Factor Data and Derivation of Assigned Protection 
Factors'' (Ex. 1-156). OSHA received 12 comments on the report. While 
some commenters expressed general support for Nicas' approach (e.g., 
Ex. 1-182-4, American College of Occupational and Environmental 
Medicine), others had serious reservations about establishing APFs 
using this approach. The issues raised by these commenters are 
described below.
1. Lack of Valid and Reliable WPF Data
    Two commenters stated that the available WPF data were of 
insufficient quality to permit a sophisticated statistical analysis. 
The 3M Company (3M) commended OSHA for ``attempting to use science to 
evaluate workplace studies for determining Assigned Protection 
Factors,'' but stated that insufficient valid data were available for 
such an evaluation, and that the data that were available were too 
variable (Ex. 1-182-5). In addition, Organization Resource Counselors, 
Inc. (ORC) stated: ``The use of existing, often flawed, workplace 
protection factor studies, is not a solution to the problem. * * * A 
reliance on sophisticated statistics in an attempt to compensate for a 
lack of reliable scientific data on respirator performance is both bad 
science and bad policy'' (Ex. 1-182-10).
2. Inappropriate Use of ANOVA Model
    Three commenters believed that using Nicas' lognormal ANOVA model 
to analyze existing data was inappropriate (Exs. 1-174, 1-182-5, 1-182-
1). Two of these commenters advocated using a simple analysis of the 
aggregate data instead (Exs. 1-174, 1-182-5). Thomas Nelson (Ex. 1-174) 
and 3M (1-182-5) expressed concern that the ANOVA model focuses 
primarily on within-wearer and between-wearer variability, while 
ignoring the potential variability contributed by other sources such as 
work site, respirator model, filter, and contaminant. Nelson stated: 
``A simple analysis of the entire data (i.e., geometric mean, estimates 
of percentiles and confidence intervals) includes these and other 
possible sources of variation and the within-person variability in the 
model.'' Two other commenters, Drs. Rappaport and Kupper [contractors 
for the Industrial Safety Equipment Association (ISEA)] believed that 
using an ANOVA model provided some benefits; however, they had concerns 
regarding the assumption of log-normality of penetration values, the 
lack of validation of the model, and errors that appeared in some of 
the equations. Therefore, they regarded ``implementation of Dr. Nicas' 
ideas as being problematic at this time,'' and encouraged the industry 
to develop improved methods and data for deriving APFs (Ex. 1-182-1).
3. ANOVA Model Fails To Account for Differences Between WPF Studies
    Five commenters stated that the proposed analysis fails to account 
for important differences between studies that could affect WPF values. 
Thomas Nelson and 3M believed that the ANOVA model does not account for 
other sources of variability (Exs 1-174, 1-182-5). NIOSH stated that 
Nicas' report did not address the effect of the test subjects' work 
rates and other activities on a respirator's performance (Ex. 1-182-3), 
and did not account for employee training and program surveillance (Ex. 
1-182-9). The Chemical Manufacturers Association (CMA) also commented 
on factors not considered in the Nicas report, ``including differences 
in training, experience, work site, work rate and sample collection'' 
(Ex. 1-182-7). ORC noted: `` The results of a WPF study are based on at 
least the following components: quality of the respirator chosen; 
quality of the training program; quality of the fit testing and 
selection program; nature of the work and ability

[[Page 34045]]

to challenge the fit of a respirator (sedentary versus high exercise 
work)'' (Ex. 1-182-10).
4. Using a Conservative Criterion for Setting APFs
    Five commenters stated that Nicas' criterion for setting APF values 
was overly conservative. The Dow Chemical Company (Dow) stated that the 
Nicas approach ``would result in protection factors which are very 
conservative'' (Ex. 1-182-2), while 3M believed that OSHA's use of 
Nicas's recommendation would result in a major change in the pattern of 
respirator use (Ex. 1-182-5). NIOSH commented that the approach may 
result in very low APF estimates because of high WPF variability, and 
that while the approach would derive more conservative (i.e., more 
protective) APFs, its use for ``WPF studies with small sample sizes * * 
* could result in APF estimates less than or equal to 1.0 (APF values 
less than 1.0 are meaningless)'' (Ex. 1-182-3). Drs. Rappaport and 
Kupper stated that only weak precedence existed for Nicas' use of 95th 
percentiles to define APFs, and suggested that other percentiles (e.g., 
the 90th percentile) would be more practical to implement (ISEA, Ex. 1-
182-1). Finally, CMA believed that the proposed criterion rated ``all 
respirators on the lowest protection achieved by the lowest performing 
person'' (Ex. 1-182-7).
5. APFs Based on a Contaminant's Toxicity (Acute Versus Chronic 
Toxicants)
    Dr. Nicas proposed that two APFs be assigned to a respirator, 
depending on its use against either a chronic toxicant or an acute 
toxicant. Four commenters remarked on the feasibility and effects of 
this approach. NIOSH commented that ``defining acceptable protection 
against short-term exposures is very complex * * *.'' (Ex. 1-182-3). 3M 
commented that dual APFs would be confusing to the user community and 
workers, and would make program management difficult (Ex. 1-182-5). CMA 
provided similar comments, and noted that many materials have both 
chronic and acute effects (Ex. 1-182-7). ORC believed that:

    * * * different APFs for different contaminants or types of 
exposure is not appropriate. Occupational exposure standards should 
have adequate safety factors which are based on the health outcome 
(e.g., irritation, systemic toxicity, carcinogenicity) of exposure. 
(Ex. 1-182-10)

    While Drs. Rappaport and Kupper stated that Nicas' argument about 
respiratory protection for substances with chronic effects was logical, 
they regarded the question of how to deal with acutely toxic substances 
as unresolved (Ex. 1-182-1).
6. Distribution of Contaminant Concentrations
    Two participants believed that it was necessary to incorporate 
information on the variability of ambient exposure concentrations, as 
well as the maximum anticipated concentration, when discussing 
respirator selection. CMA stated that since an employee's exposures 
will vary from day to day, employers should select respirators with 
maximum use limits well above the mean exposure levels to ensure ``that 
there is less than 5% probability of exposures above the maximum use 
limit of the respirator'' (Ex. 1-182-7). In a related comment, ORC 
stated that many industrial applications typically have exposures only 
2-3 times the acceptable exposure limit; therefore, ``selecting a 
respirator with an APF of 10 may mean there is only a remote chance of 
overexposure to a contaminant due to fit/wear variability'' (Ex. 1-182-
10).
7. Other Concerns With Nicas' Method
    The commenters raised several other issues with Dr. Nicas' 
methodology. For example, 3M (Ex. 1-182-5) and CMA (Ex. 1-182-7) 
believed that the relationship between outside concentration and WPF 
(i.e., WPF increases with increasing Co) was poorly understood; 
therefore, a sophisticated analysis of the data is questionable. Other 
commenters noted errors in the equations of the proposed model (e.g., 
Ex. 1-182-1) and with the distribution of the respirator penetration 
values (Ex. 1-182-1).
8. Miscellaneous Comments (e.g., ANSI APFs)
    In addition to responding to the Nicas report, a number of 
commenters supported using the APFs recommended in the ANSI Z88.2-1992 
respiratory protection standard (Exs. 1-182-1, 1-182-2, 1-182-5, 1-182-
7, 1-182-10). These commenters stated that the members of the ANSI 
Z88.2 committee were ``respected industrial hygiene and respirator 
experts'' (Ex. 1-182-5), that the ANSI Z88.2-1992 APFs were ``the 
appropriate values'' (Ex. 1-182-7), and that the ANSI APFs ``have been 
through the ANSI peer review process'' (Ex. 1-182-5). In advocating use 
of the ANSI APFs, none of the commenters described the process by which 
the ANSI Z88.2 committee derived its APFs, or identified the studies 
and other information on which that committee relied. Furthermore, 
several commenters (Exs. 1-182-7, 1-182-5, 1-182-10, 1-182-6, 1-182-8) 
noted that the ANSI Z88.2-1992 standard does not explicitly account for 
several factors in assigning APF values to different respirator 
classes, or the use of a respirator in different situations, which they 
indicated were necessary considerations. Moreover, some commenters 
(Exs. 1-182-11,1-182-12) recommended APFs that differ from those 
published by the ANSI Z88.2 Committee. Other commenters believed that 
it was OSHA's responsibility to show that the commonly used ANSI Z88.2 
1992 APFs were erroneous (Ex. 1-182-2), and that the Agency should not 
use SWPF studies to derive APFs (Ex. 1-182-5). Several participants at 
the hearing for the final Respiratory Protection Standard stated that 
OSHA should issue a second NPRM to address the development of APFs 
(Exs. 1-182-1, 1-182-5, 1-182-10).
    After carefully considering Dr. Nicas' model and the comments 
received in response to his report of the model, the Agency concluded 
that other possible approaches to deriving APFs should be investigated. 
Accordingly, the Agency identified and collected available data for 
this purpose. Of particular interest were data that OSHA could use to 
discriminate between the performance of different respirator classes. 
The Agency gathered information from both published and non-published 
papers and reports, and included WPF, SWPF, PPF, and EPF studies; 
Health Hazard Evaluations conducted by NIOSH; respirator performance 
data from manufacturers, such as SWPF data submitted to OSHA by Bullard 
(Ex. 3-8); and other material related to assessing respirator 
performance. This information is in Docket H049 as Exhibits 2, 3, and 
4.
    To assist in evaluating the data, OSHA employed Dr. Kenneth Brown 
(a statistician) and several respirator authorities: Mr. Harry 
Ettinger, Dr. Gerry Wood of LANL, and Drs. James Johnson, Kenneth 
Foote, and Arthur Bierman of LLNL. After the Agency reviewed all of the 
studies and information, it decided to attempt to analyze only WPF and 
SWPF studies since they address respirator performance exclusively. 
OSHA discusses the work and findings of these individuals below.

B. Analyses of WPF Studies

    OSHA contracted with Dr. Brown to investigate possible approaches, 
other than those approaches proposed by Nicas, to evaluate respirator 
performance data from WPF studies. The following discussion is a 
general description of the analyses performed by Brown, as well as his 
overall

[[Page 34046]]

conclusions. For a detailed explanation of the methodology and 
rationale used in the analyses, refer to Brown's reports in the docket 
(Exs. 5-1, 5-2).
    OSHA reviewed the available WPF studies for possible inclusion in 
Brown's analyses. Early in this review process, the Agency decided to 
exclude WPF studies with a gas or vapor workplace challenge agent 
because: The preponderance of studies were conducted in workplaces with 
particulate challenges; gas/vapor studies did not provide any further 
insight or clarification regarding sources of variability in WPF 
studies (most likely, gas/vapor studies add variability to the data 
such as the effects of humidity on sampling media collection and 
desorption efficiencies); and pulmonary elimination differs between 
gases/vapors and particulates. Therefore, OSHA decided to analyze only 
WPF studies using particulate challenge agents. The Agency evaluated 
those studies initially selected for further analysis for compliance 
with the requirements of OSHA's Respiratory Protection Standard (29 CFR 
1910.134), as well as completeness of the data. The Agency compiled a 
list of review items to use in evaluating each study (Ex. 5-5).
    OSHA then divided the remaining studies into two categories: Half-
mask negative-pressure air-purifying respirators (APRs) and atmosphere-
supplying respirators (PAPRs and SARs). This procedure resulted in 22 
APR studies and 16 PAPR/SAR studies for analysis. OSHA placed a list of 
these studies, and their respective respirators, in the docket (Ex. 7-
4). Brown subsequently identified 14 APR studies and 13 PAPR/SAR 
studies for further analysis (see Exs. 5-1 and 5-2 for more information 
on the evaluation criteria).
    Brown's analyses divided the respirators used in these studies into 
separate respirator classes. The analyses divided APRs into 5 classes, 
listed below in Table 1. As this table shows, Brown's analyses 
separated filtering facepieces into four classes based on the 
characteristics listed under the Description column heading, with the 
fifth class comprised of elastomeric facepiece APRs.

                                                             Table 1.--Half-Mask APR Classes
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                  Description
                                                                                     -------------------------------------------------------------------
                      Class                                      Type                 Adjustable head     Exhalation      Double shell
                                                                                           straps           valve         construction   Foam ring liner
--------------------------------------------------------------------------------------------------------------------------------------------------------
1...............................................  Filtering facepiece...............  ...............  ...............  ...............  ...............
2...............................................  Filtering facepiece...............               X   ...............               X   ...............
3...............................................  Filtering facepiece...............               X                X                X   ...............
4...............................................  Filtering facepiece...............               X                X                X                X
5...............................................  Elastomeric facepiece.............
--------------------------------------------------------------------------------------------------------------------------------------------------------

    In addition, Brown's analyses divided PAPRs into five classes and 
SARs into two classes, as shown in Table 2.

                     TABLE 2.--PAPR and SAR Classes
------------------------------------------------------------------------
        Class                  Type                  Description
------------------------------------------------------------------------
1....................  PAPR                  Loose-fitting facepiece.
2....................  PAPR                  Loose-fitting facepiece
                                              with hood and/or helmet.
3....................  PAPR                  Hood and/or helmets--not
                                              loose-fitting.
4....................  PAPR                  Tight-fitting half-mask
                                              facepiece.
5....................  PAPR                  Tight-fitting full
                                              facepiece.
6....................  SAR                   Loose-fitting.
7....................  SAR                   Hood or helmet.
------------------------------------------------------------------------

    Later in the analyses, Brown further divided these classes 
according to class of respirator, study, and challenge agent (CLSA). 
This division resulted in 26 CLSAs for the APRs and 14 CLSAs for the 
PAPRs/SARs.
    The data from the WPF studies consisted of simultaneous 
measurements of the challenge agent concentration inside the respirator 
facepiece (i.e., concentration inside or Ci) and outside the respirator 
facepiece (i.e., concentration outside or Co) in the ambient workplace 
atmosphere. Corresponding Co and Ci measurements can be used to 
calculate the workplace protection factor (WPF = Co/Ci) or penetration 
of the contaminant into the respirator (PEN = Ci/Co = 1/WPF). The APR 
studies had a total of 917 data pairs, while the PAPR/SAR studies 
provided 443 data pairs.
1. Half-Mask APRs
    In the first phase of his analysis, Brown statistically analyzed 
the data for half-mask negative pressure APRs, both filtering facepiece 
and elastomeric APRs, using the following three approaches: (1) Pooled 
the data within classes, corrected the data for the positive 
relationship found between WPF values and increasing Co, and compared 
the differences in WPF statistics between classes; (2) conducted an 
intra-study analysis of the performance of two different classes of 
respirator used against the same contaminant under similar workplace 
conditions; and (3) divided the data into class-study-agent 
combinations, and evaluated WPF as a function of Co. The following 
sections discuss these approaches in detail.
    Approach 1. Brown's initial approach was to determine if he could 
pool the data within each respirator class and estimate the fifth 
percentile WPF for that respirator class; he then tested for 
differences in WPFs between the respirator classes. He divided and 
analyzed the data by study, treating the data from each study as a 
homogeneous sample arising from the same parent distribution. Then he 
examined the data in each study for a Co effect, and constructed a 
scatterplot of ln(WPF) versus ln(Co) for each respirator class. In 
doing so, he treated extreme or poorly fitting data as outliers and 
removed them from the analysis. He subsequently derived a linear 
regression of ln(WPF) on ln(Co) for each study, and extrapolated from 
the observed range to the entire range of Co values in all of the data. 
The positive slopes, which he found for most classes, showed that 
ln(WPF) increased as ln(Co) increased. In addition, the regression 
lines were well mixed, indicating that studies within the same 
respirator class varied more than anticipated. This result indicated 
that variability occurring within respirator classes could obscure 
differences between respirator classes.
    These studies collected data over different ranges of Co. 
Therefore, to compare the WPFs observed in the studies, Brown corrected 
the WPF values for all studies, using a common Co adjustment factor. He 
pooled the adjusted WPFs by class, and then plotted the cumulative 
distributions to determine if he could identify differences between 
respirator classes, despite intra- and inter-study differences. Finding 
no differences

[[Page 34047]]

between respirator classes using the Co adjustment factor, he concluded 
that:

    Observed 5th percentiles for WPFs, and their lower confidence 
intervals when adjusted for the Co effect, showed no clear evidence 
that any class was preferable to another. In particular, there was 
no indication that Class 5 (elastomerics) performed better than four 
disposable classes. (Ex. 5-1, p. 8)

    The results of these analyses prompted a more detailed examination 
of the data. To control for study-related and agent-related factors 
that may contribute to variability, Brown performed an intra-study 
analysis on two different respirator classes used against the same 
workplace challenge agent under similar workplace conditions (Approach 
2).
    Approach 2. The second approach attempted to determine respirator 
performance after controlling for study-to-study and agent-to-agent 
sources of variability. Among the half-mask APRs, the chance of 
detecting performance differences appeared to be greatest for 
comparisons between elastomeric and filtering facepiece respirators. In 
implementing this approach, Brown assumed that controlling for study 
and agent sources of variability would result in WPF differences 
attributable, in large part, to variability in respirator performance.
    Four of the studies compared the performance of elastomeric and 
filtering facepiece respirators against the same challenge agent in the 
same workplace. After reviewing these studies, a study by Meyers and 
Zhuang (Ex. 1-64-51) was selected for further analysis because it was 
recent, followed a protocol patterned after other published WPF study 
protocols, and was well documented. Brown's statistical analyses of 
this study (see Ex. 5-1, Appendix C) indicated large sources of 
variability within the study, making comparison of the two respirator 
classes difficult and tenuous. Based on plots of the data and the 
occurrence of several outliers, it appeared that even data on the same 
agent, obtained under similar workplace conditions, may not have come 
from the same parent distribution. In addition, the variability of WPFs 
within the study (regardless of adjustment for the Co effect) was 
large. Therefore, the results of this second approach led Brown to 
state that, at least in this analysis, ``workplace studies may have too 
much intra-study variability for reasonably valid/accurate/reliable 
assessments and comparisons of respirator effectiveness.'' (Ex. 5-1, p. 
C-17)
    Approach 3. Brown began the third statistical approach by dividing 
the data into units smaller than respirator class, i.e., units based on 
class of respirator, study, and workplace challenge agent (class-study-
agent or CLSA). This procedure resulted in 42 CLSA combinations. After 
removing deficient data (e.g., no data on Co), he narrowed the data set 
to 26 combinations. Again, he tested the data for each CLSA to 
determine if WPF increases with Co and, if so, whether the effect held 
for all respirator classes. Data analyses of the 26 CLSAs indicated 
that WPF increased with Co; Brown then derived a common estimate 
(across all CLSAs) of the Co effect. He subsequently estimated the 
means for the CLSAs within each class of respirator, both with and 
without adjustment for Co effect. Brown compared the means of these 
CLSAs within and between respirator classes. For each respirator class, 
he grouped the CLSAs that had no significant difference between their 
means into common subclasses, and plotted both the adjusted and non-
adjusted means [i.e., mean of ln(PEN)] of the subclasses, as well as 
their associated confidence intervals. The results of the comparisons 
showed that: the estimated means of CLSAs vary so much within a class 
that the mean of one CLSA is likely to be a poor predictor of the mean 
of another CLSA within the same class; and it was not visually apparent 
from the plots that one class of respirator performed better than 
another class. In general, the comparison indicated that study 
outcomes, even within the same class of respirator, are highly 
heterogeneous.
    Final analysis. Since the three approaches discussed above could 
not distinguish between respirator effectiveness within or across 
classes, the data were viewed, as a whole, from the relationship of Ci 
and Co. Brown pooled the data for all 26 CLSAs and derived several 
functional relationships from the pooled data. This approach showed 
that the majority of the observed data pairs achieved a WPF of 10. (See 
Ex. 5-1 for more details.)
    After performing the above analyses, Brown made a number of 
observations and conclusions. He noted that the range of WPF values 
within a CLSA was typically wide, and that the observations were highly 
variable. In addition, he believed that variability in WPF studies can 
affect the accuracy, validity, and reliability of study results, as 
well as the ability to compare study results. Brown noted several 
possible sources of variability in WPF studies, including: (1) Study 
characteristics related to study design, execution, sample analysis, 
and data management and reporting; (2) measurements of Ci at different 
outside concentrations (Co effect), taken in conjunction with other 
poorly described factors (e.g., particle size, temperature, humidity) 
that may affect the relationship of Ci and Co; (3) characteristics of 
the ambient agent itself (e.g., possible effects of the agent occurring 
in a mixture with other agents); and (4) variations in data among 
studies related to using different study procedures (e.g., repeated 
measurements on the same worker in some studies versus single 
measurements on each worker in other studies, random versus non-random 
selection of study participants). He also commented that the analyses 
assumed that the data were representative of workplace conditions; 
however, the data may not represent either current or future workplaces 
in which employees use respirators. Finally, Brown observed that 
studies with high Ci values, relative to Co, may have influenced his 
findings. He believed that these studies should be closely reviewed 
because some study weakness, unrelated to respirator performance, could 
be the reason for the high Ci values.
    Brown also made some general observations about WPF studies. First, 
he believed that the role of WPF studies in assessing and comparing 
respirator effectiveness, and influencing APFs, should be reevaluated. 
He believed that a more refined instrument that is amenable to 
experimental design and control, such as chamber studies, is better 
suited for providing information during determination of assigned 
protection factors. Brown noted that the use of high concentrations of 
a challenge agent in chamber studies may minimize the uncertainty of 
extrapolating test results obtained at low outside concentrations to 
levels well above the observed range. Therefore, WPF studies would 
serve as a counterpart to chamber studies, i.e., WPF studies would 
provide data on the respirator during actual use in the workplace, and 
identify workplace conditions in which a respirator may perform poorly. 
To improve comparability of results, he advocated using uniform 
procedures to: select the challenge agent; collect samples; record the 
data; and measure and interpret Ci and Co (Ex. 5-1, pp. 42-44).
    Overall, the analyses led Brown to several conclusions. First, 
workplace studies have limitations for comparing respirator performance 
because of uncontrolled sources of variability. Support for this 
conclusion comes from the wide confidence intervals for the means of 
the CLSAs, and the wide range of those confidence intervals within the 
same respirator class. Second, Brown believed that the WPF has limits 
as a

[[Page 34048]]

measure of respirator effectiveness because, in general, it tends to 
increase as Co increases. This relationship complicates comparisons of 
WPF values measured at different Co levels. Third, he found no clear 
evidence that one class of respirator is better than any other class, 
particularly between elastomeric half-mask and filtering facepiece 
respirators. In addition, the differing results between CLSAs within 
the same class of respirators indicated that the outcome of one CLSA 
may be a poor predictor for another CLSA in the same class.
2. PAPRs and SARs
    Dr. Brown analyzed 13 studies to evaluate and compare the 
effectiveness of PAPRs and SARs. Ten of the studies were conducted with 
PAPRs, and three with SARs. Brown's analyses divided these ``high-
performance'' respirators into seven classes (i.e., five types of PAPR 
and two types of SAR) based on their design features (see Table 2), 
with subsequent separation of these respirator classes into 14 CLSAs.
    Brown used the CLSAs to determine whether any differences in 
respirator effectiveness existed among the respirator classes. He 
analyzed the data for trends of WPFs, either upward or downward, as Co 
increases, and for homogeneity. Brown plotted all of the data, fitted 
lines to these plots, made comparisons of study results within each 
respirator class, and developed functions from the fitted lines. (For 
additional details on these statistical analyses and the data plots, 
see Ex. 5-2.)
    On reviewing the data plots, Brown concluded that the data were 
consistent with a linear relationship between ln(Ci) and ln(Co). Also, 
the presence of outliers and/or an imbalanced distribution of the 
observations influenced the results. He recommended further 
investigation of the outliers, particularly those with unusually high 
Ci values, to determine if they resulted from characteristics of the 
respirator or other variables. He also recommended studying the 
imbalanced distributions to determine if they represented individual 
study biases caused, for example, by collecting data at different work 
sites or on different work shifts. Finally, Brown noted that the robust 
least trimmed squares line may be useful for estimating the 
relationship between ln(Ci) and ln(Co).
    Fifth percentiles are commonly used as a benchmark for respirator 
performance. Brown's analyses showed that fifth percentile estimates 
differed considerably within respirator classes that contained more 
than one CLSA. The range of the fifth percentile estimates was 28-389 
for the five CLSAs in Class 2, 17-107 for the two CLSAs in Class 4, 29-
1779 for two CLSAs in Class 5, and 74-188 for the two CLSAs in Class 7. 
The fifth percentile estimates in Classes 3 and 6 were large, while the 
fifth percentile estimates were small in Classes 1, 4, and 7. Brown 
believed that, while some of these differences may be attributed to a 
real difference in respirator performance between classes, the sample 
sizes were too small and/or the sampling variability too large to 
obtain reliable estimates at low percentile levels. He noted that the 
fifth percentile estimates were variable, and were not predictable from 
one CLSA to another CLSA within the same respirator class. Thus, he 
concluded that the fifth percentile estimates of WPFs have limited 
utility for setting assigned protection factors. Table 3 lists the 
descriptive statistics for WPFs, for each class-study-agent 
combination.

                                             Table 3.--Descriptive Statistics for WPF, by Class, Study Agent
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                           CL1.26.Cd       CL2.22.Pb       CL2.23.Pb       CL2.24.Si        CL2.3.BAP       CL2.5.Asb       CL3.27.EBZ
--------------------------------------------------------------------------------------------------------------------------------------------------------
Curve Label...........................               1              2a              2b               2c              2d       No curves                3
Median................................        2,972.97          127.88          155.29         3,553.72        1,788.32          156.00        11,935.87
Range.................................       25,186.05        1,040.75        6,131.76        95,518.07        8,203.89          537.00     4,746,673.83
Minimum...............................           53.70           22.58           28.24            36.31          371.49           66.00         1,152.26
Maximum...............................       25,239.75        1,063.33        6,160.00        95,554.38        8,575.38          603.00     4,747,826.09
No. Observations (N)..................              33              46              43               59              20               7               58
5th Percentile........................          280.25           27.82           35.03            92.07          388.70           70.50         1,797.79
10th Percentile.......................          581.87           53.04           43.08           267.60          407.51           75.00         2,365.29
Reject Lognormality?..................              No              No              No               No              No              No              Yes
Geometric Mean........................        2,523.49          126.85          184.69         2,765.75        1,408.10          151.95        15,623.81
Geometric Stan. Dev...................            3.56            2.28            3.21             6.33            2.50            2.54             5.56
---------------------------------------
                                           CL4.21.Si       CL4.6.Pb        CL5.18.Pb       CL5.21.Si        CL6.19.Si       CL7.25.Sr       CL7.28.Si
---------------------------------------
Curve Label...........................              4a              4b               5        No curves               6              7a               7b
Median................................           48.67          438.60        7,948.14            85.44        9,178.81        3,827.16         2,480.55
Range.................................          176.27        2,310.33       73,081.90           189.92       34,735.48       87,137.82        33,384.67
Minimum...............................           16.40           23.00          579.04            24.75          668.34           41.67            43.33
Maximum...............................          192.67        2,333.33       73,660.94           214.67       35,403.82       87,179.49        33,428.00
No. Observations (N)..................               7              25              53                4              15              21               52
5th Percentile........................           17.20          107.06        1,779.12            29.10        1,407.60           74.07           188.14
10th Percentile.......................           18.00          160.95        2,300.18            33.50        2,229.66           79.37           383.47
Reject Lognormality?..................              No              No              No      N too small              No              No               No
Geometric Mean........................           49.20          400.34        8,319.09            76.10        7,389.62        2,315.04         2,066.00
Geometric Stan. Dev...................           23.60            2.81            3.03            25.60            2.92            9.99             4.02
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The objective of the review of these 13 WPF studies was to see what 
can be learned about the performance of each respirator class, and its 
relative effectiveness, based on the data for Co and Ci. He also 
attempted to determine how Ci changes as Co changes, and what factors 
affected this relationship.
    Brown found too much unexplained variability between study 
outcomes, even within the same respirator class and within similar 
ranges of Co, to make valid and reliable comparisons. He noted that 
study outcomes for the same class of respirator may differ 
significantly, which raised concerns about interpreting the outcome for 
a class from a single study. More specifically, he questioned whether 
the results from one study would be similar

[[Page 34049]]

to another study. He concluded that it is not possible to know to what 
extent the outcome of a study is attributable to characteristics of the 
respirator used.
    Brown believed that the variability identified in this analysis was 
probably due to uncontrolled parameters in the workplace test 
situations, such as aerosol particle size distributions and densities, 
and work activities. Based on the data from these studies, he found 
that WPF tends to increase as Co increases (equivalently, penetration, 
or PEN., tends to decrease). He believed that the probability of a Co 
dependence for WPFs seemed to be established by his analyses.

C. Analyses of SWPF Studies

1. Bullard Models 77 and 88, Clemco Apollo Models 20 and 60, and 3M 
Whitecap II
    In the mid-1980s, SWPF studies provided OSHA with information on 
the effects of temperature, relative humidity, airflow, and facial hair 
on respirator performance (LANL, 1988; Ex. 1-64-101, LLNL, 1986; Ex. 1-
64-94). More recent SWPF studies provided additional information on the 
performance of the following abrasive blasting respirators: the Bullard 
Models 77 and 88 (Ex. 3-8-3), the Clemco Apollo Models 20 and 60 (Ex. 
3-7-3), and the 3M Whitecap II (Ex. 3-9-2).
    OSHA contracted with Mr. Harry Ettinger to review and comment on 
the study principles and protocols described in the five reports 
(Bullard, Clemco, 3M Whitecap, the LLNL study, and the LANL study). His 
report (Ex. 3-3) contained the following observations and conclusions.
    Mr. Ettinger noted that while the reports do not satisfy the 
typical criteria for defining peer-reviewed publications, this was not 
a serious problem because the studies were conducted in national 
laboratories by knowledgeable and experienced investigators. 
Furthermore, the review procedures generally used by these national 
laboratories most likely provide a sufficient peer-review process. He 
noted that none of the reports provided sufficient detail to permit a 
statistical re-analysis of the data by OSHA. In addition, he observed 
that the studies of the Bullard, Clemco, and 3M respirators reported 
considerably higher fit factors than the 1986 and 1988 national 
laboratory studies. However, he believed that it was not appropriate to 
compare the results of recent studies with the older studies, but he 
noted that older respirators may not perform as well as newer designs.
    Mr. Ettinger also noted that the tests of the Bullard, Clemco, and 
3M respirators satisfied the established criteria of fit factors that 
exhibited only brief negative pressure spikes. He believed these 
results indicated that if these devices are used and maintained 
properly, they appear to have fit factors of at least 20,000. He 
believed that, using a safety factor of 20, a protection factor of 
1,000 is attainable, assuming that the testing protocol is adequate.
    Ettinger stated that he could not define clearly a relationship 
between the older and more recent study results. For example, he 
suggested that the additional exercises in the more recent study (ORC, 
2001; Ex. 3-4-2) did not adequately represent normal or extreme work 
situations. Ettinger cautioned against assuming that all blasting 
helmets would achieve the high fit factors measured in the recent 
studies because performance is device specific, and indicated that 
older respirator designs may need to be reevaluated. Furthermore, he 
believed that quality control, human factors, minimum flow rate, and 
the sturdiness of respirator construction are important variables that 
should be evaluated in the testing protocol.
2. NIOSH N95 Study
    In 1999, NIOSH conducted a chamber study of 21 N95 respirators (20 
filtering facepiece, and 1 elastomeric, respirators) and statistically 
analyzed the respirators' performance (Ex. 4-14). At the request of 
OSHA, Drs. Johnson, Foote, and Bierman of LLNL undertook a review of 
this study to assist the Agency in evaluating APFs of half-mask 
respirators (Ex. 3-2). OSHA provided the raw data files from the study 
to LLNL for independent evaluation.
    The NIOSH investigators used ambient (i.e., room) aerosol as the 
challenge agent, and a PortaCount to measure respirator penetration. 
Use of ambient aerosol does not require aerosol generation equipment, 
thereby circumventing use of a possibly hazardous chemical. However, if 
this technique generates a low ambient particle concentration it is 
difficult to detect the reduced number of particles that penetrate the 
respirator; this effect results in an artificially low protection 
factor. In addition, an ambient aerosol that is varying in 
concentration during testing can cause error in the penetration 
measurements. Study participants can also produce aerosols ranging from 
0.1 to 3 particles/cc through their breathing (i.e., ``breathing'' 
background). Whenever the amount of challenge agent that penetrates the 
respirator is low (i.e., on the order of particles/cc or less), the 
PortaCount cannot distinguish between particles in the breathing 
background and the challenge aerosol penetrating the respirator. The 
LLNL researchers believed that the breathing background can limit fit 
factor measurements to 1,000 and less when the challenge concentration 
is below 2,000 particles/cc (Ex. 4-15). They concluded that challenge 
aerosol concentrations can be better controlled in chamber studies than 
under this protocol.
    When calculating faceseal leakage, the NIOSH authors assumed that 
all study participants have the same constant volumetric flow rate 
through the respirator. Using a filtration model developed by Rubow 
(Ex. 3-7-3), the LLNL reviewers determined media penetration that was 
approximately 5% less than the media penetration calculated by the 
NIOSH authors using the constant flow rate assumption. Since the method 
used by the NIOSH authors results in only a 5% error, and gives a 
conservative estimate of the filter penetration, the LLNL reviewers 
believed that the constant flow rate assumption is reasonable. The LLNL 
reviewers also discussed other considerations, including fluctuations 
in peak flows under various exercise conditions, and the correction 
factor for filter media penetration used by the NIOSH authors.
    Investigating the possible effect of breathing background on the 
PortaCount fit factor measurement, the LLNL reviewers applied an 
estimated worst-case scenario to the data. The scenario consisted of 
the following two assumptions: (1) A challenge aerosol concentration of 
3,000 particles/cc, and (2) a breathing background of 5 particles/cc. 
Applying these assumptions to the NIOSH data, the LLNL reviewers 
recalculated total penetrations, and adjusted the results for breathing 
background. They found that, when compared to the NIOSH results, 14 of 
the 21 respirators had more tests passing the 0.01 penetration criteria 
than before. The LLNL reviewers also calculated the 50th and 95th 
percentiles for the penetration data, both with and without applying 
the breathing background assumption. In view of their results, they 
believed that the original NIOSH analysis and findings result in a 
conservative estimate of the respirators' performance.
    The LLNL reviewers also used the NIOSH raw data to reproduce 
values, geometric standard deviations, and the 95th percentile for 
total penetration, filter penetration, and face seal leakage. They then 
compared these results to total penetration and face seal leakage 
penetrations summarized in the NIOSH study (Exs. 4-1, Table 2; 4-14, 
Table I).

[[Page 34050]]

The few discrepancies were small, and could be attributed, for example, 
to rounding off values. The 95th percentiles in the NIOSH study were 
based on a formula using the geometric mean and geometric standard 
deviation, and assumed that the distribution was log normal. For 
comparison, the reviewers calculated the 50th and 95th percentiles 
based on the raw data alone (i.e., assuming no distribution). Using 
this approach, the LLNL reviewers noted that, for many respirator 
models, the 50th percentile differed markedly from the geometric mean. 
They also saw differences between the 95th percentile calculated using 
a log normal distribution and the corresponding percentile determined 
directly from the data. LLNL reviewers stated that the NIOSH study 
demonstrated the advantages of SWPF studies for half-mask respirators. 
Their results confirm the quality of this important SWPF study of 
filtering facepiece and elastomeric half-mask respirators.
3. ORC Study of PAPRs and SARs
    In 1997, ORC and a group of its member companies sponsored a study 
of 11 powered air-purifying and supplied-air respirators (PAPRs and 
SARs) to evaluate the protection that these respirators afforded to 
workers in the pharmaceutical industry. The study, ``Simulated 
Workplace Protection Factor Study of Powered Air Purifying and Supplied 
Air Respirators' (Ex. 3-4-1) was completed in 1998 by researchers at 
LLNL. OSHA requested Dr. Gerry Wood of LANL to evaluate ORC's LLNL 
study. He evaluated the study using the data received from ORC, as well 
as information on the study published in the American Industrial 
Hygiene Association Journal (Exs. 3-1, 3-4-2).
    The raw data files from the study consisted of instantaneous (0.1 
second) photometer aerosol measurements obtained before, during, and 
after 12 exercise periods (including four periods of normal breathing) 
performed by each study participant. The instantaneous penetration 
results for the 144 tests were plotted against time. Wood examined 
patterns of aerosol penetration into the respirator that occurred 
throughout testing, noting that certain exercises often exhibited 
penetration spikes. He found that running in place produced the most 
penetration spikes. However, he also noted other respirator/subject 
combinations result in spikes. Wood indicated that such non-random 
distributions of readings was not surprising, as different movements 
during an exercise should affect instantaneous penetrations 
differently.
    Wood calculated 95% confidence limits for the average and maximum 
penetration values during each exercise. In doing so, he assumed that 
pre-test and post-test background, and chamber aerosol measurements 
were distributed normally, since no movement variables were present. He 
then calculated aerosol penetration. Wood found that the photometer 
reading averages and standard deviations that he analyzed for all 144 
data sets were in agreement with the LLNL figures, and that rounding 
off figures accounted for any minor differences in average penetrations 
that he calculated.
    In summary, Dr. Wood believed that the quality of the data, 
experimental protocol, measurements and data, and calculations applied 
to the data in the ORC-LLNL study were excellent. He agreed with the 
authors' conclusions that SWPF studies are useful for comparing 
respirators, and that the study protocol was reproducible.

D. OSHA's Overall Summary Conclusions

    Prior to this current rulemaking, OSHA explored several procedures 
to evaluate and compare respirator performance across models, studies, 
agents, and testing protocols. The Agency thoroughly reviewed the 
available data on respirator performance to determine the current 
concepts, and possible methodologies, for deriving APFs. To evaluate 
the data, OSHA had to make several decisions.
    For example, while OSHA was aware that particle size can affect 
concentration values, the Agency was unable to quantify this factor 
based on available information. Consequently, OSHA did not attempt to 
adjust for differences in particle size in the analyses. Furthermore, 
the Agency had to decide how to address sampling results that were 
below the limit of detection (LOD). Accordingly, whenever sampling 
results were below the limit of detection, OSHA set the Ci at a 
percentage of the LOD reported in the study. When the study reported 
extremely low Ci results as a percentage of the LOD, the Agency used 
the values provided by the authors.
    OSHA was concerned that the analyses be those best able to account 
for parameter uncertainty, and be a measure of respirator effectiveness 
that is valid over a plausible range of concentrations for each of the 
agents against which the respirator is to be used. As discussed above, 
the Agency contracted with Drs. Nicas and Brown to independently 
evaluate the raw WPF data. As a result of these analyses, OSHA 
preliminarily agrees with Drs. Rappaport and Kupper, who indicated 
that, while some modeling may be useful, concerns remain regarding the 
lack of model validation (Ex. 1-182-1). Furthermore, OSHA finds merit 
in Thomas Nelson's comment that a simple analysis of the entire data 
may sufficiently cover the relevant sources of variation in these data 
(Ex. 1-174). Databases of the information used by the Agency in its 
analyses have been placed in the docket for review by interested 
parties (Exs. 5-3, 5-4, 5-5).
    The Agency also recognizes that WPF and SWPF studies have their 
strengths and weaknesses. SWPF studies can control for a number of 
variables, thus providing less variable results across respirators 
classes than WPF studies. Also, SWPF studies can test respirators 
safely at the limits of their effectiveness. However, WPF studies 
evaluate respirators during use in the workplace. Therefore, the Agency 
believes that WPF or SWPF studies provide complementary information.
    OSHA developed the proposed APFs using a multi-faceted approach. 
The Agency reviewed the various analyses of respirator authorities, 
available WPF and SWPF studies, and other APF literature. For example, 
OSHA reviewed Brown's analyses and noted no difference in performance 
between filtering facepiece and elastomeric half-mask APRs, and that 
few data pairs from the combined data sets analysis failed to achieve a 
WPF of 10. In addition, the data from WPF and SWPF studies, as well as 
a qualitative review of the available APF literature, supported an APF 
of 10 for all half-mask APRs. Therefore, OSHA is proposing an APF of 10 
for half-mask APRs. The Agency used a similar approach in developing 
the remaining proposed APFs.
    In conclusion, the APFs proposed by OSHA in this rulemaking 
represent the Agency's evaluation of all the available data and 
research literature; i.e., a composite evaluation of all the relevant 
quantitative and qualitative information. The Agency seeks comment on 
this approach, as well as the proposed APFs developed using this 
approach.

E. Summaries of Studies

    Researchers often determine the protection afforded by a respirator 
by conducting Workplace Protection Factor (WPF) studies and Simulated 
Workplace Protection Factor (SWPF) studies. A WPF study measures the 
effectiveness of respirators under workplace conditions. Workers 
participating in a WPF study wear respirators while performing their 
usual job tasks. The WPF is a measure of the reduction in exposure 
achieved while using respiratory protection and

[[Page 34051]]

is the ratio of the concentration of the contaminant found in the 
workplace air to the concentration found inside the respirator 
facepiece. Similarly, a SWPF study measures the ratio of a 
contaminant's concentration both outside and inside the facepiece. 
However, researchers obtain these measurements in test chambers, which 
allows them to control some important variables (e.g., outside 
concentration of the challenge agent). Rather than performing the 
actual job tasks found in a particular work setting, the study 
participants perform a series of exercises in the test chamber that 
simulate the actions of workers in general.
    In developing the proposed APFs listed in Table 1 of the proposed 
amendments to the standards (Section XII). OSHA reviewed data from 
properly conducted WPF studies and SWPF studies. In addition, the 
Agency reviewed published APF tables. These data formed the basis for 
OSHA's proposed APFs. OSHA also reviewed other types of studies, such 
as Effective Protection Factors (EPF) and Program Protection Factor 
(PPF) studies, along with respirator performance studies that lacked 
raw data. A review of those studies can be found in the Docket (Exs. 3-
10, 3-11). However, EPF and PPF studies account for aspects of 
respirator use other than effectiveness of the respirator while it is 
being worn, while studies that lack raw data give little information 
for in-depth statistical analysis. Therefore, OSHA relied on WPF and 
SWPF studies, since they attempt to account for actual use conditions 
and focus on the performance characteristics of the respirator only.
1. WPF Studies--Filtering Facepiece and Elastomeric Half-Mask 
Respirators
    Study 1B. C.E. Coulton, H.E. Mullins, and J.O. Bidwell gave a 
presentation at the May 1994 American Industrial Hygiene Conference and 
Exposition (AIHCE) on worker protection afforded by the same respirator 
in two different environments and against two different contaminants 
(Ex. 1-64-13). At the first site, the authors determined exposure to 
cadmium dust for 18 workers in a plastic colorant manufacturing 
facility. They determined exposure to lead fume for 18 workers during 
ship breaking and recycling at the second site. At the colorant 
facility, cadmium-containing pigments were weighed, mixed with plastic 
resin, and fed into extruders for production of concentrated colorant. 
Samples were obtained from workers in the weighing, mixing, and 
extruding areas. Workers at the ship breaking facility used torches to 
cut an aircraft carrier into large sections that were then cut into 
smaller pieces on shore. Burners and firemen, on the ship and on shore, 
were sampled for lead. Work rate at the colorant facility was judged to 
be low, while the work rate of the ship breaking workers was assessed 
as being moderate. The respirator used in the study was a 3M 6000 
series elastomeric half-mask equipped with either 3M 2040 or 3M 2047 
HEPA filters (the 2047 HEPA filter has some activated charcoal for 
removal of nuisance levels of organic vapors). Employees normally wore 
the study respirator and were provided with training in its proper 
donning, fitting, and operation. In addition, the employees had to pass 
a saccharin qualitative fit test prior to study participation; they 
also had to be clean-shaven. The study was explained to the 
participants and they were observed on a one-on-one basis throughout 
the sampling periods.
    The inside-the-facepiece sampling train consisted of a 25 mm three-
piece cassette with a 0.8 micron pore size mixed cellulose ester 
filter. Respirators were probed with a Liu probe inserted opposite the 
mouth and projecting one cm into the facepiece. The sampling cassette 
was attached directly to the probe, and a cassette heater was utilized 
to prevent condensation of moisture from exhaled breath. Outside-the-
facepiece samples used a 25 mm three-piece cassette with a 0.8 micron 
pore size mixed cellulose ester filter. The outside sample cassette was 
also connected to a Liu probe, and this combination was attached in the 
worker's breathing zone. Inside samples and outside samples were 
collected at a flow rate of 2 Lpm. Respirators were donned and doffed, 
and sampling trains started and stopped, in a clean area. Field blanks 
were used for contamination evaluation. Particle size distribution was 
ascertained with a six-stage single-jet cascade impactor that sampled 
all day at 1 Lpm.
    Samples were analyzed by inductively coupled plasma (ICP) 
spectroscopy. For both cadmium and lead, the authors presented the 
range of outside concentrations, inside concentrations, and the 
associated geometric means and standard deviations. Three sets of WPFs 
were determined for cadmium and lead, based on three different methods 
for reporting inside samples that were below the limit of detection 
(LOD) (i.e., calculating WPF using 70% of the LOD; calculating WPF 
using the LOD; or eliminating these samples from the WPF calculation 
database). No field blank adjustments were made (i.e., no cadmium or 
lead detected), and no mention is made of adjusting the data for 
pulmonary retention of particles. In addition, samples were invalidated 
as a result of equipment and procedural problems, and if the outside 
filter weights were less than 100 times the limit of detection (or 101 
times the field blank value). The authors reported a mean WPF of 353, 
with a fifth percentile of 34, for the cadmium samples, and a mean WPF 
of 135, with a fifth percentile of 15, for the lead fume samples. The 
authors noted a sizable difference in WPFs for cadmium and lead (using 
the same respirator), and discussed a number of possible reasons for 
the difference (e.g., differences in particle size, work environment, 
work rate). The authors concluded that the ANSI Z88.2-1992 recommended 
APF of 10 for half-facepieces was appropriate.
    Study 1C. In a poster presentation at the 1992 AIHCE, C.E. Coulton 
and H.E. Mullins provided results of a study of several contaminants 
(Ex. 1-146). Exposure to iron (Fe), manganese (Mn), titanium(Ti), and 
zinc (Zn) were determined for shipyard workers involved with welding 
and grinding. The respirators studied were 3M 9920 and 3M 9925 dust/
fume/mist disposable respirators.
    At the Agency's request, 3M provided the raw data from the study, 
but the information provided had no discussion of sampling or 
analytical methodologies. However, in a brief abstract, the authors 
mention using blank samples and observing participants during sampling 
(in the context of discarding particular sample sets). Outside- and 
inside-the-facepiece concentrations, and associated WPFs, were provided 
for the four analytes: Fe (31 data sets), Mn (32 data sets), Ti (28 
data sets), and Zn (32 data sets). Calculated WPFs ranged as follows: 
24 to 1010 for Fe, 10.21 to 715 for Mn, 50.38 to 2545 for Ti, and 27.41 
to 854.89 for Zn. Tom Nelson (Ex. 135) calculated a geometric mean (GM) 
of 147, a geometric standard deviation (GSD) of 2.5, and a best 
estimate fifth percentile of 33 for the 32 sample sets he used in 
evaluating this study. The information he provided contained no 
additional discussion of the results or study conclusions.
    Study 1D. Workplace performance of an elastomeric half-mask against 
exposure to lead was reported in 1984 by S.W. Dixon and T.J. Nelson for 
11 workers in an unidentified work environment (Ex. 1-64-19). The 
participants' work rate was judged to be moderate to heavy. Workers 
viewed a training program and selected from three mask sizes of a 
Survivair 2000 elastomeric half-mask respirator,

[[Page 34052]]

equipped with organic vapor/high-efficiency particulate filters. 
Participants were qualitatively fit tested with isoamyl acetate. Prior 
to participation, employees were quantitatively fit tested with a 
Dynatec/Frontier FE250A portable unit while wearing the Survivair with 
high-efficiency filters and performing six ANSI-recommended exercises. 
In addition, paired (before and after) quantitative fit tests were 
performed for about half of the WPF determinations to ascertain if 
quantitative fit tests can predict WPFs. Participants were instructed 
not to break the faceseal during sampling, and were observed throughout 
the sampling period.
    Samples were collected on 25 mm 0.8 micron pore size polycarbonate 
filters, for 30 to 120 minutes (a complete job cycle) at a flow rate of 
2 Lpm. Sampling trains were calibrated before and after each day's 
sampling, and respirators were disassembled, cleaned, and reassembled 
at the end of each day. The authors do not provide a more detailed 
discussion of the inside or outside sampling trains (e.g., type of 
respirator probe, placement of outside sampling apparatus). Particle 
size analysis was performed using light microscopy and scanning 
electron microscopy.
    Proton induced x-ray emission analysis (PIXEA) was used to analyze 
the samples. This method's limit of detection was 2 nanograms per 
sample. The authors provide an approximate particle aerodynamic 
diameter based on the particle size analyses. Inside-the-facepiece 
results were corrected for losses caused by the sample probe but were 
not corrected for lung deposition (which the authors believed caused 
only a small bias). Thirty-seven WPFs were determined; however, the 
individual data sets (i.e., inside concentration, outside 
concentration, and associated WPF) were not provided. During the study, 
some participants were observed to break the faceseal to talk. The 
authors provide an overall range of WPFs achieved, GM, and GSD, for 
undisturbed facepiece samples and pooled disturbed and undisturbed 
facepiece samples. The authors reported a GM WPF of 3,400, and a best 
estimate of the fifth percentile of 390 when the facepiece was not 
disturbed, and a GM WPF of 2,400, and a best estimate of the fifth 
percentile of 160 when the facepiece was disturbed. The authors also 
found no correlation (at the 5% level) between WPF and outside 
concentration, or the relationship between WPF and quantitative fit 
factors for predicting workplace protection. The authors also estimated 
the program protection factor based on historical measures of air lead 
concentrations versus blood lead levels (a table and graph of this data 
was provided). They concluded that the half-mask respirator they tested 
provided WPFs that exceeded an APF of 10, and provided program 
protection factors (PPFs) that exceeded 10.
    Study 2. Workplace protection against exposure to asbestos fibers 
(chrysotile and amosite) was reported at the 1985 AIHCE by T.J. Nelson 
and S.W. Dixon for 17 workers who removed asbestos-containing materials 
at two sites (Ex. 1-64-54). Six of these workers were removing asbestos 
fireproofing from a ceiling at the first site, while eleven workers at 
the second site were removing asbestos-containing pipe insulation. The 
participants' work rate was judged to be moderate, site temperatures 
ranged from 65-85 degrees Fahrenheit, and humidity was very high.
    The following six brands of half-mask respirators were studied: 3M 
8710 disposable dust/mist respirator; 3M 9910 disposable dust/mist 
respirator; American Optical R1050 disposable dust/mist respirator; 
Survivair 2000 elastomeric respirator with high-efficiency filters or 
DFM filters; MSA Comfo II elastomeric respirator with high-efficiency 
filters or DFM filters; and a North 7000 elastomeric respirator with 
high-efficiency filters. Participants were trained in respirator use by 
the investigators and were qualitatively fit tested using the saccharin 
fit test. Supplemental data indicate that participants wore one or more 
respirator brands. No mention is made of respirator donning and doffing 
procedures, or starting sampling trains in a clean area; however, the 
sampling procedures state pumps were stopped and cassettes removed in a 
dust-free area. Participants were observed by the researchers 
throughout the sampling period.
    The inside-the-facepiece sampling train was a 25 mm closed-face 
three-piece cassette with a \1/2\-inch extender, containing a 0.8 
micron pore size mixed cellulose ester filter. The cassette was 
attached directly to a tapered probe inserted into the respirator 
midway between the nose and mouth. In-mask samples were collected at a 
flow rate of 2.0 Lpm. The outside-the-facepiece sampling cassettes and 
probes were identical to the inside-the-facepiece sampling train and 
were fastened to the lapel of the subject. Outside samples were 
gathered at 0.5 to 1.0 Lpm. Sampling times ranged from 30 to 120 
minutes, and the pumps were calibrated before and after each sampling 
period. The authors investigated uniform deposition of asbestos fibers 
across the filters; they noticed a slight trend for heavier deposition 
at the filter center using both methods. They also computed the 
precision of sample gathering using open- versus closed-face cassettes 
and found no difference between the methods.
    Asbestos analysis was based on NIOSH method P&CAM 239 and NIOSH 
method 7400 (i.e., the filter mounting and ``A'' counting rules). To 
increase analytical sensitivity, the methodology was modified by 
counting fibers in a minimum of 500 fields per inside-the-facepiece 
filter when less than 100 fibers were counted. The actual number of 
fibers counted in each sample was used to compute the airborne 
concentration. In addition, one microscopist performed all fiber 
counting. The distributions of fiber length and diameter were 
determined by transmission electron microscopy using lapel sample 
filters. The GM and GSD values for the fiber length, fiber diameter, 
and equivalent aerodynamic diameter at each worksite and the combined 
data from both sites were reported, but the values for fiber density 
and the length-diameter correlation coefficient were not provided. A 
total of 84 pairs of inside and outside fiber concentrations, and 
corresponding WPFs, were provided by participant, respirator brand, and 
sampling period in supplemental data tables. However, the authors 
considered seven WPF values measured for the American Optical 
respirator as suspect because the inside-the-facepiece filter samples 
contained glass fibers, originating from the respirator's filter 
matrix. These glass fibers have the same appearance as asbestos fibers 
under light microscopy. The authors did not adjust measured values for 
field blank values (i.e., blanks were below the limit of 
quantification) or fiber retention in the respiratory tract (i.e., the 
authors believed that pulmonary fiber retention resulted in only a 
slight change in concentration inside the facepiece).
    The 3M 8710 results showed a GM WPF of 310, a GSD of 5.3, and a 
best estimate of the fifth percentile of 20. The 3M 9910 had a GM WPF 
of 580, a GSD of 4.2, and a best estimate of the fifth percentile of 
55. The AO R1050 had a GM WPF of 52, a GSD of 4.2, and a best estimate 
of the fifth percentile of 5. The Survivair 2000 or MSA Comfo II 
equipped with DFM filters had a GM WPF of 240, a GSD of 6.3, and a best 
estimate of the fifth percentile of 12. With high-efficiency filters, 
the GM WPF was 94, the GSD was 3, and the best estimate of the fifth 
percentile was 16. For the North 7700 equipped with high-efficiency 
filters, the GM WPF was

[[Page 34053]]

250, the GSD was 6.9, and the best estimate of the fifth percentile was 
11.
    Since the WPFs for respirators equipped with DFM and high-
efficiency filters were similar, and were well below the protection 
expected if filter efficiency alone was the determining performance 
factor, the authors concluded that ``* * * filter efficiency was not as 
significant a factor in determining the relative workplace performance 
against asbestos as the face fit''. The authors also noted comparable 
performance between disposable and elastomeric respirators. With regard 
to this, the authors noted that perspiration and wetting solutions led 
to the elastomeric facepieces slipping on the participants' faces, 
something that was not noted with the fibrous disposable respirators. 
The authors postulate that the effect of this slippage could be a 
reason why the two types of respirators had similar performance.
    Study 3. In 1993, A. Gaboury and D.H. Burd performed a WPF study by 
measuring exposure to benzo(a)pyrene [B(a)P] on particles among 22 
workers in a primary aluminum smelter (Ex. 1-64-24). The participants 
were rack raisers, stud pullers, and rod raisers on anode crews. The 
following three brands of elastomeric half-mask respirator devices were 
studied: Willson, Survivair, and American Optical. (Note: Respirator 
model numbers were not provided) The respirators were equipped with 
combination organic vapor/acid gas cartridges and DFM pre-filters, with 
the exception that dust/mist pre-filters were used on the American 
Optical respirator. The study also examined the performance of a 
powered air-purifying respirator (PAPR), but only the negative-
pressure, air-purifying half-mask respirator data are presented here 
(the PAPR results are discussed below). The participants had used 
respirators for several years, had been previously trained in the use 
of the particular respirator under study, and had used it for more than 
six months. All participants in half-mask respirators were clean-shaven 
and were quantitatively fit tested using the TSI Portacount. The 
minimum acceptable fit factor was 100. Industrial hygiene technologists 
assisted participants with donning and doffing respirators, cleaned and 
maintained the respirators at the end of each work cycle, and observed 
participants on a one-to-one basis throughout the sampling period. 
Participants were directed not to tamper with the respirator or 
sampling equipment. Due to the high heat in the work area, the employer 
required that employees rest in a cool environment for one-half hour 
during each hour.
    The inside-the-facepiece sampling train consisted of a closed-face 
three-piece cassette with a 25 mm organic binder free glass fiber 
filter, backed with a cellulose ester pad. The sampling cassettes were 
connected to a tapered Liu probe inserted into the respirator between 
the nose and mouth. The outside-the-facepiece sampling train was 
identical to the inside-the-facepiece sampling train; however, no 
mention is made of connecting the cassette to a Liu probe. All filters 
were pre-calcined at 400 degrees Centigrade for 24 hours. Both inside 
and outside samples were collected at a flow rate of 2 Lpm for 
approximately 300 minutes, or one-half of the 10-hour work shift. 
Respirators and sampling trains were worn and operated until the 
employee entered the rest area; they were donned and started prior to 
leaving the rest area for the next work cycle. Sampling cassettes were 
plugged when not in use and the respirators were cleaned after each 
work cycle. Field blanks were used to identify possible contamination 
due to handling. Sampling train airflow rates were checked at the 
beginning, middle (i.e., after lunch), and end of the work day; on 
changing the cassettes; and when a problem was suspected. Sampling 
occurred over a five-day period. Only stud pullers and rod raisers used 
the elastomeric half-mask respirators.
    B(a)P analysis followed the Alcan Method 1223-84. The 
ambient B(a)P particle size distribution was determined by collecting 
four samples, as close as possible to the workers, using an 8-stage 
Anderson cascade impactor (Model 296). Impactor samples were collected 
for two to five hours at a flow rate of 2 Lpm. The average percent of 
B(a)P mass (across four samples) per impactor stage (defined by an 
aerodynamic diameter cut point, in micrometers) was reported. About 93% 
of the B(a)P mass was associated with particles having diameters of 
less than 9.8 micrometers. A total of 18 pairs of inside and outside 
sample concentrations, with associated WPFs, were provided by brand of 
respirator and job category, but were not linked to specific 
participants. Overall GM, GSD, and 95% confidence interval on the mean 
were also provided for the inside and outside concentrations and WPF, 
along with an overall fifth percentile WPF. The authors stated that 
some employees participated more than once during the study. No mention 
is made of adjusting inside-the-facepiece concentrations for particle 
retention in the respiratory tract. The half-masks had WPF ranging from 
13 to 410, with a GM of 47. The two-sided 95% confidence intervals were 
30 and 74 for the dual cartridge respirators. The fifth percentile was 
9. The authors found no significant relationship between B(a)P 
concentrations inside and outside the facepiece. Also, while the data 
were limited, the authors believed no correlation existed between WPF 
and quantitative fit factor. The authors concluded that the fifth 
percentile for the half-masks they tested were in agreement with the 
APF of 10 recommended by the NIOSH RDL.
    Study 6. S.W. Lenhart and D.L. Campbell reported in 1984 on a WPF 
study in which they measured protection against exposure to particulate 
lead (Pb) for 25 primary lead smelter workers; seven of whom worked in 
the sinter plant and eighteen of whom were in the blast furnace area 
(Ex. 1-64-42). The predominant aerosol forms of lead were dust in the 
sinter plant and fume in the blast furnace. In both areas, lead 
comprised about 50% of the total aerosol particulate with composition 
of the remaining 50% being unknown. All participants wore an MSA 
elastomeric half-mask with high-efficiency filters. (Note: No 
respirator model number was provided) The study also examined the 
performance of an MSA PAPR, but only data for the negative-pressure, 
air-purifying half-mask respirator are presented here (the PAPR results 
are discussed below). The employees routinely used respirators; 
however, no mention is made of them with respirator training. 
Participants were quantitatively fit tested using an unspecified 
method, and had to achieve the employer's required fit factor of 250. 
Workers were instructed not to remove or manipulate the respirator 
during sampling, and were observed by the researchers throughout the 
sampling period.
    The inside-the-facepiece sampler consisted of a closed-face 37 mm 
cassette containing an AA filter and AP10 support pad. This cassette 
was connected to a tapered Liu probe that was inserted into the 
respirator between the nose and upper lip. In-mask samples were 
collected at 2 Lpm. The outside-the-facepiece sampling train was a 
closed-face 37 mm cassette containing an AA filter and AP 10 support 
pad; no tapered Liu probe was used. The outside sample cassette was 
attached to the worker's lapel. Outside samples were gathered at 2 Lpm. 
The authors collected samples for as much of each 8-hr work shift as 
possible. Respirators and sampling trains were donned and doffed, and 
samplers were started and stopped, in a lead-free area. Respirator 
facepieces were wiped clean inside

[[Page 34054]]

prior to donning after each break and cleaned and sanitized after each 
shift. One WPF was measured for each employee. The ambient particle 
size distribution was determined using 19 Marple cascade impactor 
samples (11 in the sinter plant; 8 in the blast furnace area).
    Lead analysis was by flame atomic absorption spectroscopy according 
to NIOSH Method S-341. Inside-the-facepiece samples that contained less 
than l0ug of lead were reanalyzed by graphite furnace atomic absorption 
(limit of detection = 0.2 [mu]g). The ranges for the mass median 
aerodynamic diameters (in micrometers) and for the GSD values were 
reported. A total of 25 pairs of inside and outside half-mask values, 
and the corresponding WPFs, were provided by employee, job title, and 
job location. An overall GM and GSD of the WPFs, and various percentile 
WPFs, were provided. When samples contained lead below the level of 
detection, the authors reported concentration values ``* * * determined 
from the least amount of lead detectable by the analytical method and 
the sampled volume of air.''
    In-mask values were not adjusted for particle retention in the 
respiratory tract (the authors imply retention probably had a non-
significant effect on results, but could result in overestimated WPFs). 
No mention is made of the investigators using field blanks. They 
reported that approximately 98% of the WPFs would be expected to be at 
or above 10, 90% above 30, and 75% would be expected to be above 100. 
They concluded that an APF of 10 was appropriate for the half-mask 
negative pressure air-purifying respirator evaluated in this study. The 
authors also discussed two proportional methods of defining an APF.
    Study 7. W.R. Meyers and Z. Zhuang conducted a 3-part workplace 
protection factor study in three different work environments. In 
addition to presenting the study findings, the authors also discuss 
their rationale for selecting exposure agents, study facilities, and 
workers; study procedures followed at the sites; and analytical 
methods. W.R. Meyers and Z. Zhuang in January, 1993 (Ex. 1-64-51) and 
W.R. Meyers, Z. Zhuang, and T.J. Nelson in 1996 (Ex. 3-12) reported on 
the first part of the study in which the authors determined protection 
against exposure to particulate lead (Pb), zinc (Zn), and total 
airborne mass (TAM) for 25 workers, on day and evening shifts, in three 
brass foundries (3, 9, and 13 participants, respectively). (Note: The 
reports mention 26 participants, but data were presented for only 25 
participants.) Four brands of half-mask devices were studied: 3M 9920 
disposable DFM respirator; American Optical 5-Star elastomeric 
respirator with DFM filters (R56A); MSA Comfo II elastomeric respirator 
with DFM filters (Type S); and Scott Model 65 elastomeric respirator 
with DFM filters (642-F).
    Participants were selected from volunteers who normally wore 
respirators, were clean-shaven, and passed a fit test. Their work rate 
was subjectively determined by observing their work activities. 
Respirators were worn for the usual period. For the elastomeric half-
mask respirators, the participants were quantitatively fit tested using 
a TSI Portacount; a fit factor of 100 or more constituted a pass. 
Disposable respirators were fit tested using the saccharin qualitative 
fit test. The investigators trained the participants in the proper 
donning and adjustment of the respirators, and instructed them not to 
remove or lift the respirator from their face in the work area. 
Readjustment of the respirator had to be accomplished by sliding the 
facepiece on their face. Workers were observed throughout the sampling 
period. Each participant wore two or more respirator brands, and one 
WPF was measured per employee for each brand worn.
    The inside-the-facepiece sampling train was a 25 mm closed-face 
cassette attached directly to a flared mouth probe, inserted into the 
respirator opposite the mouth. The cassette contained a 0.5 micron pore 
size polyethylene filter and polypropylene backup pad. A 4.5 mm ring 
under the filter restricted airflow to an 18 mm circle in the center of 
the filter to keep deposition in an area that could be entirely covered 
by the proton beam used for sample analysis. A heating bonnet was slid 
over the outside of the cassette to minimize condensation of moisture 
from exhaled breath. Sampled air was then drawn through a moisture trap 
using a personal sampling pump operating at 2 Lpm. The outside-the-
facepiece sampling train was a 10 mm nylon cyclone attached to 25 mm 
closed-face cassette (the cassette was not connected to a flared mouth 
probe). The cassette contained a 0.5 micron pore size polyethylene 
filter and polypropylene backup pad. A 4.5 mm ring under the filter 
restricted airflow to an 18 mm circle in the center of the filter. This 
sampling train was attached in the lapel area and samples were 
collected at a flow rate of 1.7 Lpm.
    Two separate samples were gathered during the shift, one during the 
first half and another during the second half. Individual WPFs were 
based on monitoring times of approximately one to four hours. 
Respirators were donned and doffed, and sampling trains were started 
and stopped, in a clean area. Elastomeric facepieces were cleaned and 
inspected at the end of each shift, but were not wiped out during the 
shift unless such wiping was a standard practice before the study (the 
authors noted that most of the time workers did not wipe out 
facepieces). Air-purifying filters (cartridges) and disposable 
respirators were changed at the end of each shift unless the employer's 
policy dictated more frequent changing. In addition, the mouth of the 
in-mask probe was plugged whenever the respirator was not being worn. 
Working (field) blanks and manufacturer's (media) blanks were used to 
determine possible contamination of filters due to handling or 
manufacturing. The investigators also washed the interior of the 
sampling cassettes to ascertain retention of sample particles on the 
cassette wall. The ambient particle size distribution was determined by 
PIXE 8-stage cascade impactor samples at several work locations in each 
foundry. These area samples were collected at roughly mid-chest to 
shoulder level of workers for approximately 1 hour, to prevent impactor 
overloading.
    All samples were analyzed by proton induced X-ray emission analysis 
(PIXEA). The mass distribution of Pb, Zn, and TAM by particle 
aerodynamic diameter was graphically presented for all cascade impactor 
samples. Across the three foundries, 66 pairs of inside-the-facepiece 
and outside-the-facepiece concentrations, and the corresponding WPFs, 
were provided by job task, employee, brand of respirator, and analyte 
(Pb, Zn, and TAM). The authors did not adjust measured values for 
particle retention on sampling cassette walls since these losses 
appeared to be random, independent of collected mass, and of a 
negligible amount. No mention is made of correcting measured in-mask 
values for pulmonary particle retention. A foundry-specific average of 
the field blank loadings was used as a correction factor for estimating 
background and handling contamination for each foundry. Outside-the-
facepiece samples were collected as respirable particulate, thereby 
providing respirable mass levels, while in-mask samples were collected 
as total particulate mass. The authors initially assumed that particles 
larger than 10 microns did not penetrate respirator faceseals; however, 
this was found to be incorrect after analyzing in-mask particle size. 
Therefore, to avoid comparison of dissimilar measurements, the 
investigators used particle size data

[[Page 34055]]

obtained by ambient sampling to convert the respirable mass levels to 
total mass levels (using Chimera/TSI Disfit software). The reported 
levels represent these total mass values, and form the basis of the 
reported WPF values. The authors also provide data and discussion on a 
number of sampling analyses, including GM concentration of analyte by 
job task, GM concentration of analyte for in-mask and ambient 
concentrations, particle size distribution by job category, GM WPF 
estimates by job category, GM WPF by respirator type, within shift 
sampling variation, and variation between foundries. For the pooled 
data from the three foundries, the 3M 9920 filtering facepiece had a 
50% WPF of 108, a GSD of 5.2, and a fifth percentile estimate of 7. The 
AO half-mask had a 50% WPF estimate of 98, a geometric standard 
deviation (GSD) of 5.8, and a fifth percentile WPF of 5. The MSA Comfo 
II half-mask had a 50% WPF of 163, a GSD of 3.1, and a fifth percentile 
WPF of 26. The Scott half-mask had a 50% WPF of 94, a GSD of 4.8, and a 
fifth percentile WPF of 7. For all respirators a 50% WPF of 114, a GSD 
of 4.6, and a fifth percentile estimate of 9 was reported. The authors 
concluded that ``* * * dust-fume-mist (DFM) half-facepiece respirators, 
when conscientiously used, worn, and maintained, provided effective 
worker protection.''
    Study 8. W.R. Meyers and Z. Zhuang in January, 1993 (Ex. 1-64-51) 
and W.R. Myers, Z. Zhuang, and T.J. Nelson in 1996 (Ex. 3-12) reported 
on the second part of the three-part study, which evaluated protection 
against exposure to particulate iron (Fe) for 16 workers in the sinter 
plant and basic oxygen process (BOP) facility of a steel manufacturing 
plant. In addition, exposure to particulate calcium (Ca) in the BOP 
facility was determined for one worker. The five brands of half-mask 
respirators studied were: 3M 8710 disposable dust/mist respirator; 
Gerson 1710 disposable dust/mist respirator; American Optical 5-Star 
elastomeric respirator with dust/mist filters (R30); MSA Comfo II 
elastomeric respirator with dust/mist filters (Type F); and Scott, 
Model 65 elastomeric respirator with dust/mist filters (642-D).
    In general, each participant wore two or more brands, and one WPF 
was measured per employee per brand worn. One employee had one WPF 
determined for only one respirator brand. For the elastomeric half-mask 
respirators, the participants were quantitatively fit tested. A fit 
factor of 100 or more constituted a pass. Disposable respirators were 
fit tested using the saccharin qualitative fit test. The overall study 
and sampling protocols were discussed by the authors in the foundry 
portion of the investigation (see Study 7 discussion above). While not 
specifically discussed, it is assumed that the same sampling parameters 
used in the foundry study were in place during this particular study, 
unless the authors stated otherwise. These assumptions include: 
composition of the sampling trains was unchanged; individual WPFs were 
based on monitoring times of one to four hours; elastomeric facepieces 
were cleaned and inspected at the end of each shift but the insides 
were not wiped during the shift such wiping was the employer's standard 
practice before the study; air-purifying filter cartridges and 
disposable respirators were changed at the end of each shift unless the 
employer's policy dictated more frequent changing; and the in-mask 
probe mouth was plugged whenever the respirator was not being worn. In 
addition, it is assumed that the participants were clean shaven, 
normally used respirators, were trained in the proper donning and 
adjustment of the respirators, were instructed not to remove or lift 
the respirator from their face in the work area, and were observed 
throughout the sampling period.
    The inside-the-facepiece sampling train was a closed-face 25 mm 
cassette containing a 0.5 micron pore size polyethylene filter and 
polypropylene backup pad. A reducing ring under the filter restricted 
airflow to an 18 mm circle in the center of the filter to aid in PIXE 
analysis. A heating bonnet was slid over the outside of the cassette to 
minimize condensation of moisture from exhaled breath. This cassette 
was attached directly to a flared mouth probe, inserted into the 
respirator opposite the mouth. Sampled air was drawn through a moisture 
trap using a personal sampling pump operating at 1.5 Lpm. The outside-
the-facepiece sampling train was a closed-face 25 mm cassette 
containing a 0.5 micron pore size polyethylene filter and polypropylene 
backup pad. A reducing ring under the filter restricted airflow to an 
18 mm circle in the center of the filter. The cassette was not 
connected to a flared mouth probe. This sampling train was attached in 
the lapel area and samples were collected at a flow rate of 1.5 Lpm. 
(Note: Unlike the foundry portion of the study, outside samples were 
collected as total mass rather than respirable mass samples.) Sampling 
pump flows were calibrated before and after each sampling period and 
pumps were monitored at approximately 15-20 minute intervals. 
Respirators were donned and doffed, and sampling trains were started 
and stopped, in a clean area. New cassettes were used for each sampling 
period. Working (i.e., field) blanks and manufacturer's (media) blanks 
were used to determine possible contamination of filters due to 
handling or manufacturing. The investigators also washed the interior 
of the sampling cassettes to determine retention of sample particles on 
the cassette wall. The ambient particle size distribution was 
determined by PIXE cascade impactor samples. Personal impactor samples, 
rather than area samples, were collected at the steel mill sites (see 
foundry sampling procedures discussed above in Study 7).
    Analysis for Fe and Ca on inside-the-facepiece filters was by 
proton induced X-ray emission analysis (PIXEA). Due to filter 
overloading, analysis for Fe and Ca on outside-the-facepiece filters 
was by atomic absorption spectroscopy. The mass distribution of Fe by 
particle aerodynamic diameter was tabulated for all cascade impactor 
samples. A total of 54 individual pairs of inside- and outside-the-
facepiece concentrations, and the corresponding WPFs, were provided by 
shift and date, job category, employee, and brand of respirator. For 16 
workers, the WPFs reported were based on the Fe data, while Ca data 
were used to calculate the WPF for one worker (flux unloader) in the 
BOP facility. Based on analytical information, the authors did not 
adjust measured values for particle retention on the walls of the 
sampling cassette. No mention is made of adjusting inside-the-facepiece 
values for particle retention in the respiratory tract. The average 
field blank mass loading was used as a correction factor for estimating 
background contamination. The 3M 8710 had a reported GM WPF of 377, a 
GSD of 3.7, and a fifth percentile WPF of 44. The Gerson 1710 had a 
reported GM WPF of 123, a GSD of 2.7, and a fifth percentile WPF of 24. 
The American Optical elastomeric half-mask had a reported GM WPF of 
280, a GSD of 2.7, and a fifth percentile WPF of 56. The MSA Comfo II 
had a reported GM WPF of 427, a GSD of 4.3, and a fifth percentile WPF 
of 39. The Scott elastomeric half-mask had a reported GM WPF of 252, a 
GSD of 2.9, and a fifth percentile WPF of 45. The authors concluded 
that ``The 5th percentiles for the WPF distributions for each 
respirator or pooled data were greater than 20.''
    The authors also provided data and discussion on a number of 
sampling analyses, including GM concentration of analyte and GM WPF by 
job task, GM concentration of Fe inside the facepiece

[[Page 34056]]

and ambient and GM WPF by respirator brand, and particle size 
distribution by job category. The authors stated that ``* * * half-
facepiece respirators (maximum use concentration 10 times the PEL) were 
a suitable selection for the tasks included in this study.''
    Study 9. In January 1993, W.R. Meyers and Z. Zhuang reported on the 
third part of their investigation, in which they determined protection 
against exposure to particulate titanium (Ti), chromium (Cr), strontium 
(Sr) and total ambient mass (TAM) for 22 workers who spray painted 
aircraft on day, evening, and night shifts (Ex. 1-64-52). The three 
brands of half-mask elastomeric respirators studied were the: American 
Optical 5-Star, MSA Comfo II, and Scott Model 65. All respirators were 
equipped with combination high-efficiency filter/organic vapor 
cartridges.
    Twelve participants each wore two brands of respirator with a WPF 
determined for each brand worn; nine participants wore one brand of 
respirator and had one WPF determined; and one employee had one WPF 
determined for one respirator brand and two WPFs determined for another 
brand. The participants were quantitatively fit tested and a fit factor 
of 100 or more constituted a pass. The overall study and sampling 
protocol was discussed by the authors in the foundry portion of the 
studies, summarized in Study 7 above (Ex. 1-64-51). While not 
specifically discussed, it is assumed that the same sampling parameters 
were in place during this particular study as in the foundry study, 
unless the authors stated otherwise. These assumptions include: 
composition of the sampling trains was unchanged; individual WPFs were 
based on monitoring times of one to four hours; elastomeric facepieces 
were cleaned and inspected at the end of each shift but were not the 
inside was not wiped during the shift, unless such wiping was the 
employer's standard practice before the study; filters and disposable 
respirators were changed at the end of each shift unless the employer's 
policy dictated more frequent changing; and the mouth of the in-mask 
probe was plugged whenever the respirator was not being worn. In 
addition, it is assumed that the participants were clean-shaven, 
normally used respirators, were trained in the proper donning and 
adjustment of the respirators, were instructed not to remove or lift 
the respirator from their face in the work area, and were observed by 
the researchers throughout the sampling period.
    The inside-the-facepiece sampling train was a closed-face 25 mm 
cassette containing a 0.5 micron pore size polyethylene filter and 
polypropylene backup pad. A reducing ring under the filter restricted 
airflow to an 18 mm circle in the center of the filter to aid in sample 
analysis. A heating bonnet was slid over the outside of the cassette to 
minimize condensation of moisture from exhaled breath. This cassette 
was attached directly to a flared mouth probe, inserted into the 
respirator opposite the mouth. Sampled air was then drawn through a 
moisture trap using a personal sampling pump operating at approximately 
2 Lpm. The outside-the-facepiece sampling train was a closed-face 25 mm 
cassette containing a 0.5 micron pore size polyethylene filter and 
polypropylene backup pad. A reducing ring under the filter restricted 
airflow to an 18 mm circle in the center of the filter. The cassette 
was not connected to a flared mouth probe. This sampling train was 
attached in the lapel area, and samples were collected at a flow rate 
of 1 Lpm. (Note: Unlike the foundry portion of the study, outside 
samples were collected as total mass rather than respirable mass 
samples.) Sampling pump flows were calibrated before and after each 
sampling period and pumps were monitored at approximately 15-20 minute 
intervals. Respirators were donned and doffed, and sampling trains were 
started and stopped, in a clean area. New cassettes were used for each 
sampling period. Working (i.e., field) blanks and manufacturer's 
(media) blanks were used to determine possible contamination of filters 
due to handling or manufacturing. The investigators did not wash the 
interior of the sampling cassettes to determine retention of particles 
on the cassette wall, since a simple alcohol wash would not have 
removed dried paint spray. Ambient particle size distributions were not 
characterized.
    Analysis of all filters was by proton induced X-ray emission 
analysis (PIXEA). The average field blank mass loading was used as a 
correction factor for estimating background contamination. The authors 
did not mention adjusting inside-the-facepiece measured values for 
particle retention in the respiratory tract. A total of 36 individual 
pairs of inside-the-facepiece and outside-the-facepiece concentrations 
of each analyte (total airborne mass, titanium, chromium, strontium) 
were provided by shift and date, painting location on the plane (i.e., 
top, side, or underside of the aircraft), employee, brand of 
respirator, and paint type (i.e., top coat, primer). A total of 36 WPFs 
were reported by shift, task location on the plane, employee, and 
respirator brand; of the original 38 data sets, two sets were 
eliminated as outliers. For primer spraying, the reported WPFs were 
based on Cr data, while WPFs for spraying topcoat were based on Ti 
data. WPFs were not calculated for total airborne mass. The authors 
also provided data and discussion on a number of sampling analyses, 
including GM concentration of analyte (TAM, Ti, Cr) for both in-mask 
and ambient measurements by task location on the plane; GM WPF as a 
function of painting location on plane and paint type, and respirator 
brand; and GM WPF by respirator brand. The fifth percentile estimates 
for all WPF data were reported to be much greater than 10. The authors 
concluded that these half-facepiece elastomeric respirators, when 
properly worn and used in conjunction with existing controls provided 
effective worker protection.
    Study 13. G. Wallis, R. Menke, and C. Chelton reported in 1993 on a 
WPF study in which they evaluated exposure to manganese dioxide dust 
for an unknown number of participants in several alkaline battery 
manufacturing plants (number of plants not provided) (Ex. 1-64-70). All 
participants wore the disposable 3M 8710 dust/mist respirator and 
performed their normal work activities. The participants were not 
trained by the investigators, but had been previously trained and 
routinely used respirators. It was not stated whether the participants 
had ever been fit tested for the 3M 8710 respirators. Prior to 
sampling, the participants washed their faces and were taken to a clean 
area, where the study was explained. The participants were observed 
throughout the sampling period.
    The inside-the-facepiece sampling train was a closed-face 37 mm 
cassette containing a 0.8 micron pore size mixed cellulose ester 
filter. The cassette was connected to a tapered Liu probe (made of 
nylon) which was inserted into the respirator midway between the nose 
and mouth. The outside-the-facepiece sampling train was a closed-face 
37 mm cassette containing a 0.8 micron pore size mixed cellulose ester 
filter. The outside sampling cassette was attached to the employee's 
lapel. No mention is made of connection of the outside cassette to a 
tapered Liu probe. Inside- and outside-the-facepiece samples were 
collected at an airflow rate of 1.5 Lpm for 30 to 40 minutes. The 
authors chose a short sampling interval to prevent resistance across 
the inside-the-facepiece sampling filter due to a buildup of moisture 
from exhaled breath. Sampling pump flows were

[[Page 34057]]

calibrated before, and rechecked after, each sampling period. 
Respirators were donned and doffed, and the sampling trains started 
(and assumed stopped), in the clean area. Field blanks were used to 
identify possible contamination of filters due to handling. The number 
of sample pairs collected per subject was not specified. The ambient 
manganese particle size distribution was determined by 6-stage Marple 
Cascade impactor equipped with an inlet cowl to prevent debris from 
entering the impactor. Samples were collected for several hours at a 
flow rate of 2 Lpm, and flows were calibrated before and after each 
sampling interval. Four samples were gathered: One in the powder drop 
area (Plant A) and three at the bag slitting operations (one in Plant 
A, two in Plant B).
    Samples were analyzed for Mn by atomic absorption (AA) spectroscopy 
according to NIOSH Method 7300. The mass distribution of Mn by particle 
aerodynamic diameter was tabulated for all cascade impactor samples. 
Less than 30% of the mass was associated with respirable particles. A 
total of 70 individual pairs of inside-the-facepiece and outside-the-
facepiece concentrations, and the corresponding WPFs, were provided by 
job activity (but not by employee or plant). No mention is made of 
adjusting measured values for particle retention in the respiratory 
tract or results of field blank analysis. A GM of 50 and a GSD of 3.5 
was reported for all the WPF values measured. A calculated fifth 
percentile protection factor of 7.5 was also reported. The authors 
reported that their data indicated a systematic dependence of WPF on 
the concentration outside the respirator. In their discussion of this 
observation, the investigators refer to three possible causes presented 
by authors of other studies: Program protection factors tend to be low 
in low exposure settings since the workers, aware of the low exposure, 
exercise less care; low outside concentrations result in inside-the-
facepiece concentrations so small that reliable quantification is 
difficult; and filter efficiency increases with loading, and low 
concentrations do not adequately load the filter. The authors discuss 
these causes relative to their study results, and postulate that 
another cause may be particle size selectivity (i.e., smaller particles 
have a higher probability of entering the respirator). They conclude 
that it is important to characterize respirator performance in the 
environment where the respirator will be used.
    Study 14. At the 1990 AIHCE, C.E. Colton, A.R. Johnston, H.E. 
Mullins, C.R. Rhoe, and W.R. Meyers presented a WPF study in which they 
measured protection against exposure to aluminum dust for five 
participants working as carbon changers in an aluminum smelter (Ex. 1-
64-15). All participants wore the disposable 3M 9906 dust/mist 
respirator. The investigators trained the participants in donning the 
respirator and the participants were qualitatively fit tested, although 
the fit test method was not described. The total number of samples 
collected per employee was not specified, although it is stated that 
the five employees were sampled daily for five days. Participants were 
observed throughout the sampling period.
    The inside-the-facepiece sampling train was a closed-face 25 mm 
cassette containing a 0.8 micron pore size polycarbonate filter. The 
cassette was connected to a tapered Liu probe, inserted into the 
facepiece in an unspecified location. In-mask samples were collected at 
an airflow rate of 2.0 Lpm. The outside-the-facepiece sampling train 
was a closed-face 25 mm cassette containing a 0.8 micron pore size 
polycarbonate filter. Outside samples were gathered as respirable dust 
samples with the cassette being connected downstream from a cyclone 
apparatus. Sampling airflow rate was 1.7 Lpm. Sampler airflow rates 
were calibrated before and after each sample period. No mention is made 
of donning and doffing procedures. Field blanks were used to identify 
possible filter contamination caused by handling. The ambient aluminum 
particle size distribution was determined through 12 area samples 
(unspecified locations) collected by Marple personal cascade impactors. 
In addition, particulates that passed a cyclone selector were sized by 
optical microscopy.
    Aluminum was determined by proton induced x-ray emission analysis 
(PIXEA). The mass distribution of aluminum by particle diameter and 
percent penetration to the collector was graphically presented. Final 
calculations used only those outside filter weights that were greater 
that 11 times the detection limit. A total of 24 time-weighted-average 
(TWA) inside-the-facepiece and outside-the-facepiece concentrations, 
with corresponding TWA WPFs, are provided in supplemental data (Ex. 1-
146). The sample pairs are not linked to specific participants. No 
mention is made of adjusting sample results for particle retention in 
the respiratory tract. The mean blank value was zero, so no adjustment 
to measured values was made. The authors reported a GM of 27, a GSD of 
1.5, and a fifth percentile of 13 for the 23 sample sets used. The 
report concluded that the respirator provided reliable WPFs of 10. 
Cumulative probability of achieving a particular WPF, and the effect of 
filter weight on WPF, were also graphically presented. The authors 
stated that the WPFs represented conservative estimates of protection 
since outside concentrations were measured as respirable dust. In the 
summary of this study (Ex. 1-146), submitted to OSHA along with the raw 
sampling data, the authors recommended that the study not be used to 
assess the ultimate APF for this class of respirator since they felt 
that the real WPF of the respirator was significantly underestimated.
    Study 15. C.E. Colton, H.E. Mullins, and C.R. Rhoe presented a WPF 
study at the 1990 AIHCE in which they determined exposure to 
particulate Pb and Zn for 17 participants working in core making, mold 
making, pouring, and cleaning areas of a brass foundry (Ex. 1-64-16). 
All participants wore the disposable 3M 9970 high-efficiency 
respirator. The investigators trained the participants in the proper 
donning and fitting of the respirator, and participants were fit tested 
using the saccharin qualitative fit test method described in Appendix D 
of OSHA's Lead Standard (29 CFR 1910.1025). Sampling took place over 
five days.
    The inside-the-facepiece sampling train was a 25 mm three-piece 
cassette containing a 0.8 micron pore size polycarbonate filter (open- 
versus closed-face was not specified). The cassette was directly 
connected to a tapered nylon Liu probe, inserted into the facepiece 
midway between the nose and mouth. The inside-the-facepiece samples 
were collected at a flow rate of 2.0 Lpm. The outside-the-facepiece 
sampling train was a 25 mm three-piece cassette containing a 0.8 micron 
pore size polycarbonate filter. Outside samples were gathered as 
respirable dust samples, with the cassette being connected downstream 
from a 10 mm nylon cyclone. Samples were collected at a flow rate of 
1.7 Lpm, and sampling pumps were calibrated before and after each 
sample. The authors do not mention using of field or manufacturer's 
blanks, respirator donning and doffing procedures, or methods of 
starting and stopping sampling trains in a clean area. The ambient Pb 
and Zn particle size distributions were determined by an unspecified 
number of Marple personal cascade impactor (Model 2401) samples.
    Pb and Zn were determined by proton-induced x-ray emission analysis 
(PIXEA). The particle size data were not presented; however, the report 
stated that the Pb and Zn aerosols were present as both dust and fume. 
The range of

[[Page 34058]]

outside-the-facepiece and inside-the-facepiece concentrations for Pb 
and Zn were provided. For the purpose of WPF calculation, inside-the-
facepiece samples with non-detected concentrations were treated as 
containing analyte at the detection limit (This situation only arose 
with lead, not zinc). For the 62 sample sets taken for lead, the GM WPF 
was 415, the GSD was 4.4, and the fifth percentile WPF was 36. For 
zinc, the GM WPF was 681, the GSD was 5.6, and the fifth percentile WPF 
was 40. The authors believe they handled their results conservatively 
since outside concentrations were collected as respirable particulate, 
rather than total mass, and inside-the-facepiece samples with non-
detected concentrations were given values of the analytical detection 
limit when calculating WPF. In the study summary, the authors concluded 
that when the respirator is properly selected, fit tested, and used, 
their results supported its use for concentrations up to 10 times the 
PEL.
    Study 16. A.R. Johnston and H.E. Mullins reported at the 1987 AIHCE 
on a WPF study in which they measured exposure to particulate aluminum 
(Al), titanium (Ti) and silicon (Si) for three participants working in 
the polishing and grinding area of an aircraft components manufacturing 
facility (Exs. 1-64-34, 1-146, 1-133). Although WPFs were also measured 
for two other participants, one in the blasting area and one in the 
coating area, no data were presented for these employees. All 
participants wore the disposable 3M 8715 dust/mist respirator. Prior to 
testing, the investigators trained the participants in the proper 
fitting of the respirator, fit tested the employees using the OSHA Lead 
Standard's saccharin qualitative fit test method, and explained the 
study to them. Participants had previously worn respirators, but on an 
``as needed'' or elective basis only. Employees were observed one-on-
one throughout the sampling period. The number of WPFs measured per 
subject was not specified, although it appears that about six WPFs were 
measured per subject.
    The inside-the-facepiece sampling train was a closed 25 mm three-
piece cassette containing a polycarbonate filter. The cassette was 
connected to a tapered nylon Liu probe that was inserted into the 
facepiece at an unspecified location. Inside-the-facepiece samples were 
collected at a flow rate between 1.5 and 2 Lpm. The outside-the-
facepiece sampling train was a closed 25 mm three-piece cassette 
containing a polycarbonate filter. The cassette was connected 
downstream from a tapered Liu probe. Outside samples were collected at 
a flow rate between 1.5 and 2 Lpm. Sampling times ranged from 35 to 235 
minutes. Sampling pumps were calibrated three times a day--at the 
beginning of the shift, lunch, and the end of the shift. Sampling 
equipment was removed for breaks, which occurred multiple times in some 
instances. While no mention is made of using a clean area to don and 
doff respirators, and start and stop sampling trains, the authors noted 
that cassettes had to be removed in the work area. Field blanks were 
used to identify possible filter contamination due to handling. The 
ambient particle size distribution was not characterized.
    Samples were analyzed by proton induced x-ray emission analysis 
(PIXEA). Sample results were adjusted for field blank values, but no 
mention was made of adjustments for particle retention in the 
respiratory tract. The authors rejected sample sets in which: the 
outside filter weight was less than 11 times the mean blank value; the 
inside filter weight was non-detectable, or less than the mean field 
blank value; or the measured WPF was determined to be an outlier (i.e., 
too far above or below the geometric mean WPF using 5% confidence 
intervals). A total of 38 sample sets were accepted for Al (10), Ti 
(14), and Si (14). Pairs of inside-the-facepiece and outside-the-
facepiece concentrations, and the corresponding WPFs, are provided in 
supplemental data (Exs. 1-146, 1-133), but were not linked to specific 
participants. Also, a table of GM WPF, GSD, and fifth percentile WPF, 
by analyte, was presented. The authors calculated WPF values for the 10 
sample sets of Al, reporting a GM of 145, a GSD of 2.3, and a fifth 
percentile of 32. For the 14 sample sets measured for Ti, the GM was 
59, the GSD was 1.7, and the fifth percentile was 24. For Si, using 14 
sample sets, the GM was 172, the GSD was 3.1, and the fifth percentile 
was 24. The authors concluded that their study supports using this 
respirator for concentrations up to 10 times the PEL. In addition, the 
authors noted a positive correlation between filter weight and WPF. Two 
explanations put forth for this effect were that respirators work 
better with higher dust loadings, and that WPF measurements are more 
accurate at higher dust loadings. The authors favored the latter 
explanation, and believed that to assess true respirator performance 
capabilities, testing should be conducted at or near the respirator's 
APF, or a filter weight versus protection factor curve should be 
defined for predicting performance at higher concentrations. In a 
summary of this study submitted to OSHA (Ex. 1-146) the authors stated 
that:

    * * * the mass outside the respirator was very low. For this 
reason, the ability of the respirator to provide protection was not 
challenged. Therefore, this study should not be used for direct 
comparison to others in assigning protection factors as they are 
artificially low.

    The authors also discussed sampling and analytical considerations 
for WPF studies, such as calibration reliability, sample cassette 
integrity, analytical sensitivity, and sample handling procedures.
2. WPF Study--Full Facepiece APR
    Study 2A. C.E. Colton, A.R. Johnston, H.E. Mullins and C.R. Rhoe of 
the 3M Occupational Health and Environmental Safety Division in 
May,1989 gave a presentation at the AIHCE on their WPF study (Ex.1-64-
14) performed with full facepiece air-purifying respirators worn in a 
secondary lead smelter. Air sampling for lead was conducted over 5 days 
in four areas of the plant; the blast furnace, reverberatory furnace, 
casting, and warehouse areas.
    The respirator evaluated was the 3M 7800 Easi-Air full facepiece 
respirator used with 3M 7255 high efficiency filters. The respirator 
was equipped with a nosecup inside the facepiece. The sampling probe 
was inserted into the respirator in place of the speaking diaphragm to 
assure a gas tight seal and consistent probe location close to the 
breathing zone of the wearer. The respirators were equipped with 
sampling probes using a design by Dr. Ben Liu to minimize particle 
entry losses. Both the inside and outside sampling trains used the Liu 
designed probe for consistency.
    Thirteen workers who normally wore full facepiece respirators in 
the plant qualified to participate in the study. They were trained in 
proper respirator use, the procedures to be followed for the study, and 
how to don and fit the 3M respirator. Quantitative fit testing was 
performed using the Portacount QNFT instrument and fit test operators 
followed the OSHA Lead standard exercise protocol for fit testing. The 
workers were fit tested wearing their normally required personal 
protective equipment (PPE), and care was taken to assure that this 
additional PPE did not interfere with facepiece fit. The criterion the 
authors used for passing the QNFT was a minimum fit factor of 500; 10 
times the assigned protection factor of 50 given in the lead standard 
for a full facepiece negative pressure respirator. The 13 qualified 
workers were measured for face length and width, and

[[Page 34059]]

all the workers except 1 were in Grids 1-4 of the Los Alamos Test 
Panel. The one remaining worker's his face was wider than those 
accommodated by the Los Alamos Test Panel.
    Samples were analyzed by proton induced x-ray emission analysis 
(PIXEA) for lead. The authors reported that for PIXEA the sensitivity 
is good, typically 10 nanograms per sample. Area samples for particle 
size analysis were also collected, using Marple cascade impactors, in 
the reverberatory furnace, casting, and warehouse areas. Three particle 
size ranges were found; less than 1 [mu]m (15% of the total aerosol), 
between 1 to 10 [mu]m (20% of the total aerosol), and greater that 10 
[mu]m (65% of the total aerosol). The particle size distribution showed 
that both lead dust and lead fume were present.
    The authors had pre-established that if the outside filter weights 
were less than 51 times the field blank value, the sample set would be 
rejected. The authors stated, ``You need at least this much 
differential between inside and outside samples if you want to prove or 
disprove that a respirator provides a PF of 50.'' None of the workplace 
samples were rejected for being less than 51x the field blank value. 
However, several sample sets were rejected for other reasons such as 
the inside sample coming loose from the probe, sample pump failure, 
etc. Field blanks were used, and were handled the same as other 
samples. Detectable amounts of lead were found on the field blanks. The 
mean value of the field blanks was used to correct the sample values by 
subtracting the mean field blank value from the inside and outside 
sample weights. WPFs were calculated by dividing the outside 
concentration (Co) by its corresponding inside concentration 
(Ci), and checked for outliers. The authors reported that 
for the 20 samples collected the geometric mean WPF was 3929 and the 
GSD was 9.6, and the 5th percentile WPF estimate was 95. The outside 
concentrations ranged from 150 to 8380 [mu]g/m\3\, and the inside 
concentrations ranged from 0.03 [mu]g/m\3\ to 3.0 [mu]g/m\3\. Sampling 
periods ranged from 30 minutes to 3 hours. The workers were under 
constant observation to ensure proper respirator use and wear and to 
ensure sample validity.
    The authors looked at subsets of the data using multiples of the 
field blank mean values ranging from 1,000 times the field blank to 
25,000 times the field blank value. The authors found a strong 
correlation between filter weight and workplace protection factor when 
they looked at the log of the mean filter weight and the log of the 
mean WPF. The authors stated that the data appeared to be close to the 
plateau region. The authors also stated that the quantitative fit 
factors measured during worker fit testing did not correlate with the 
WPFs measured in this study.
    The authors concluded that `` * * * the results of this study 
indicate that this full facepiece respirator with high efficiency 
filters reliably provides workplace protection factors in excess of 50 
against lead dust and fume aerosol.'' The authors stated that they 
would expect 95% of the workplace protection factors to be above 95. 
They also stated that ``The ANSI Z88.2 proposed Standard for Practices 
for Respiratory Protection has assigned a protection factor of 100 to 
this type respirator. These data support that recommendation.''
3. WPF Studies--Powered Air-Purifying and Supplied-Air Respirators 
Half-Mask PAPRs
    Study 21. In 1983, W.R. Meyers and M.J. Peach of NIOSH reported 
half and full facepiece PAPR performance measurements for four workers 
during bagging of micro-crystalline silica (Si) in a silica processing 
plant (Ex. 1-64-46). The study examined several aspects of the 
respirator's performance. Prior to the workplace evaluation, dioctyl 
phthalate (DOP) was used to determine filter efficiency. A 4-hour Si 
dust chamber study was performed by mounting the PAPR on an 
anthropomorphic head, simulating worker breathing, and gathering 
inside- and outside-the-facepiece silica samples. Workers were provided 
with an unspecified brand of PAPR, with either a tight-fitting half-
mask or full facepiece, and equipped with high-efficiency filters. Both 
styles of facepiece were made of natural rubber and had two exhalation 
valves. The sealing edge of the facepiece was either an internal roll 
(half-mask) or a flat edge with an inner flap (full facepiece). The 
filters were located downstream of the respirator's blower unit.
    The PAPRs used in the study were identical to those already being 
used by the employees; the authors did not mention training the 
participants in proper use of the respirator. Respirators were placed 
on and removed from the participants by the investigators, as needed 
(e.g., start of shift, lunch break, personal breaks, end of shift). 
Donning and doffing the respirator, and sampling train starting and 
stopping, occurred in a clean area. Samplers were started after the 
PAPR was donned and turned on, and were stopped before the PAPR was 
turned off for doffing. Facepiece interiors were examined for dust 
contamination after each removal (gross contamination was not 
observed), and the facepieces were cleaned by the investigators after 
each shift. In addition, each PAPR's volumetric air output (with the 
facepiece removed) was measured with a dry gas meter. Filters and 
batteries were changed according to the manufacturer's instructions. 
While no mention is made of fit testing the participants, the 
investigators instructed them not to manipulate, lift, or remove the 
facepiece during sampling. Participants were observed 100% of the time 
during donning and doffing, and about 80% of the time at their 
workstations. The authors used field blanks to assess contamination 
caused by handling.
    The sampling train for the inside-the-facepiece samples consisted 
of a 37 mm two-piece cassette containing a 5 micron pore size FWS-B 
polyvinyl chloride filter. The cassette was attached directly to a 
modified Luer adaptor sampling probe, inserted into the facepiece 
between the nose and upper lip of the employee. The flow rate of the 
pump was 1.5 Lpm. The outside-the-facepiece samples were collected with 
a 37 mm two-piece cassette and a 5 micron pore size FWS-B polyvinyl 
chloride filter. The sampling airflow rate was 1.5 Lpm, and the 
cassette was attached to the subject's lapel. Outside samples were 
collected as total dust since previous sampling revealed 70% or more of 
the dust particles to be 10 microns or less in size (i.e., respirable). 
Sample times ranged from 84 to 320 minutes, with cassettes being 
changed during the employees' lunch break. Overall PAPR performance 
(leakage) was determined by replacing the facepiece of two respirators 
with an air-filtering head containing a pre-weighed 76 mm glass fiber 
filter. The respirators were mounted in a free-standing stationary 
position, and run for 6-7 hours (with a battery change at 4 hours). The 
air output was measured, the filter weighed, and the ambient Si 
concentration estimated. Area samples were collected to determine 
particle size. An Anderson impactor was placed 4-8 feet from the 
participants and collected samples for about 3 hours at a flow rate of 
1 cfm.
    Samples were analyzed for free Si according to NIOSH P&CAM 259 
(i.e., gravimetric weight and x-ray powder diffraction for Si). Results 
were corrected for the average blank filter weight gain, but not for 
pulmonary retention (which the authors believed was negligible). Ten 
individual inside- and outside-the-facepiece concentrations, with 
associated WPFs, are tabulated by sample period, worker,

[[Page 34060]]

type of facepiece, and sample time. The study reported that the half-
mask PAPR did not provide the protection factor of 1,000 previously 
expected; instead, the protection factors ranging from 16 to 193. The 
authors also provided results for DOP filter penetration, aerodynamic 
mass median particle size and GSD, x-ray powder diffraction tests, and 
free-standing PAPR leakage measurements. The researchers discussed 
several parameters that could have affected results, including poor 
respirator use practices of the participants (which the authors 
believed they controlled and maintained at a minimal level); inside-
the-facepiece sampling flow rate (which the authors believed was not a 
major source of error); and inherent PAPR leakage (however, the free 
standing PAPR results indicated minimal leakage). Also discussed as 
reasons for the low protection factors were possible leakage of Si past 
the blower housing grommet when employees bumped the PAPR during work 
(the effect of this was unknown) and leakage from inadequate facepiece 
fit (which the authors considered could be significant at moderate to 
heavy work rates).
    Study 6. S.W. Lenhart and D.L. Campbell of NIOSH reported in 1984 
on a WPF study in which they measured protection against exposure to 
particulate lead (Pb) for 25 primary lead smelter workers; 7 of the 
employees worked in the sinter plant, and 18 worked in the blast 
furnace area (Ex. 1-64-42). The predominant aerosol forms of Pb were 
dust in the sinter plant and fume in the blast furnace. In both areas, 
Pb comprised about 50% of the total aerosol particulate, with 
composition of the remaining 50% of particulates being unknown. All 
participants wore an MSA half-mask PAPR with high-efficiency filters 
(the authors provided no respirator model number in the report). The 
study also examined the performance of an MSA negative-pressure air-
purifying respirator, which is discussed above in the half-mask air-
purifying respirator study summaries. The participants routinely used 
respirators, but the investigators do not mention respirator training 
for the employees. The participants were not normally fit tested with 
the half-mask PAPR facepiece; however, for this study, they had to 
achieve a fit factor of at least 250 while wearing a negative pressure 
air-purifying respirator with the same half facepiece as the PAPR. 
Employees were instructed not to remove or manipulate the respirator 
during sampling, and were observed throughout the sampling period.
    The inside-the-facepiece sampler consisted of a closed-face 37 mm 
cassette containing an AA filter and AP10 support pad. This cassette 
was connected to a tapered Liu probe that was inserted into the 
respirator between the nose and upper lip. In-mask samples were 
collected at 2 Lpm. The outside-the-facepiece sampling train was a 
closed-face 37 mm cassette containing an AA filter and AP 10 support 
pad (with no tapered Liu probe used). The outside sample cassette was 
attached to the worker's lapel. Outside samples were gathered at 2 Lpm. 
Samples were collected for ``as much of the 8-hr work shift as 
possible.'' Respirators and sampling trains were donned and doffed, and 
started and stopped, in a lead-free area. The inside of the respirator 
facepieces were wiped clean prior to donning after each break, and were 
cleaned and sanitized after each shift. The PAPR batteries were 
replaced after four hours of use (i.e., according to manufacturer's 
instructions). Battery voltage was checked, and airflow rates were 
verified to exceed 15 Lpm before use. One WPF was measured for each 
participant. The ambient particle size distribution was determined by 
19 Marple cascade impactor samples (11 in the sinter plant; 8 in the 
blast furnace area).
    Analysis of Pb was by flame atomic absorption spectroscopy 
according to NIOSH Method S-341. Inside-the-facepiece samples that 
contained less than 10 [mu]g of lead were reanalyzed by graphite 
furnace atomic absorption (limit of detection = 0.2 [mu]g). The report 
provided ranges of the mass median aerodynamic diameters (in 
micrometers), as well as the GSD values. The authors provided a total 
of 25 pairs of inside- and outside-the-facepiece concentrations, and 
the corresponding WPFs, by employee, job title, and job location, as 
well as the overall GM and GSD of the PAPR WPFs and several percentile 
values. For samples containing Pb below the level of detection, the 
authors determined concentration values ``* * * from the least amount 
of lead detectable by the analytical method and the sampled volume of 
air.'' In-mask measured values were not adjusted for particle retention 
in the respiratory tract (the authors imply that retention had a non-
significant effect on the results, but could cause WPF to be 
overestimated). No mention is made of using field blanks. Two 
approaches to defining an assigned protection factor (APF) were also 
discussed. These approaches are: Defining the APF in terms of a 
specific proportion of WPFs expected to exceed the APF, and defining 
the APF ``in terms of a one-sided lower tolerance limit above which we 
may predict with a specific confidence level that 95% of the workplace 
protection factors lie.''
    The WPF for the PAPR had a GM of 380 and a GSD of 2.6, and the 
individual WPFs ranged from 23 to 1,600. Approximately 98% of the WPFs 
for the half-mask PAPR were above 50, 90% above 110, 75% above 200, 40% 
above 500, and only 25% above 1,000. The authors concluded that an APF 
of 50 was appropriate for the PAPR they tested, and that an APF of 500 
was inappropriately high for the half-mask PAPR. A protection factor 
not in excess of 50 was recommended for half-mask PAPRs. The authors 
noted that the WPFs may be too high because the workers did not 
routinely undergo a quantitative fit test screen with negative pressure 
respirators before receiving their PAPR.
4. WPF Studies--Full Facepiece PAPRs
    Study 21. W.R. Myers and M.J. Peach of NIOSH reported in 1983 on 
the performance of an unspecified brand of PAPR equipped with a tight-
fitting elastomeric full facepiece and HEPA filters; four employees 
used the respirator in a silica bagging operation (A detailed 
description of the work setting, sampling methodology, and study 
protocol for this study is presented in the discussion of Study 21 in 
the section on half-mask PAPRs above) (Ex. 1-64-46). The full facepiece 
PAPR had a sealing edge consisting of a flat edge with an inner flap. 
The participants routinely used this PAPR and, therefore, the 
investigators did not train them in its use. Fit testing was not 
performed.
    The investigators calculated WPFs for only three of the four 
employees because the sample for the fourth employee had an inside-the-
facepiece concentration less than the limit of detection, making it 
unsuitable for WPF determination. The samples were evaluated for 
crystalline Si by x-ray diffraction. The full facepiece WPFs ranged 
from 25 to 215, which are low for a PAPR. In this regard, the authors 
reported that the employees routinely bumped and rubbed the belt-
mounted motor blower housing and filter assembly during the bagging 
operation. They believed such action may have caused movement between 
the neck of the filter and the blower housing grommet; thereby 
resulting in the seal failing and allowing unfiltered air to bypass the 
filter. They reported some evidence to support this conclusion, but 
could not determine the contribution of this problem to the overall 
leakage into the facepiece. Although the blowers were checked to ensure 
each PAPR

[[Page 34061]]

delivered a minimum 115 Lpm (4 cfm) airflow to the facepiece, the 
authors concluded that ``* * * migration of contaminant into the 
facepiece of the PAPR system could be a significant source of leakage 
when the respirator is exposed to the wide ranging conditions that 
exist in the work environment.'' While the WPFs measured in this study 
were well below the level expected of a PAPR, the authors stated that 
these results ``* * * represent a more accurate measure of the level of 
worker protection that can be expected from this type of PAPR system.''
    Study 18. At the 1990 AIHCE, C.E. Colton and H.E. Mullins presented 
a WPF study in which they assessed protection against exposure to lead 
fume and dust for 20 employees working in the blast furnace, 
reverberatory furnace, casting, and baghouse areas of a secondary lead 
smelter (Ex. 1-64-12). The employees were provided with a 3M Whitecap 
PAPR with a high-efficiency filter (TC-21C-456). The investigators 
trained the employees in the proper donning, fitting, and operation of 
the respirators. Using a TSI Portacount, the investigators conducted 
fit testing while the participants performed the exercise sequence 
contained in Appendix D of OSHA's Lead Standard; the required fit 
factor was 500. Participants were observed continuously throughout the 
sampling.
    The inside-the-facepiece sampling train consisted of a 25 mm three-
piece cassette containing a 0.8 micron pore size polycarbonate filter. 
The authors mounted the sampling cassette directly to an ABS Liu probe 
and inserted the probe into the facepiece in place of the speaking 
diaphragm. The outside-the-facepiece sampling train was a 25 mm three-
piece cassette containing a 0.8 micron pore size polycarbonate filter. 
The authors did not mention attaching the outside cassette to a probe 
or the location of the sampling cassette on the employee. Airflow rates 
of the sampling pumps were calibrated in-line before and after each 
sampling interval, but no sampling airflow rate was provided. Sampling 
was conducted for as much of the 8-hour shift as possible, with 
sampling intervals ranging from 1 to 4 hours. Field blanks were used, 
and area samples for particle size analysis were gathered with a Marple 
personal cascade impactor (Model 2401).
    Sample and field blank analyses were performed using proton induced 
x-ray emission (PIXE) analysis. Particle size analysis by inductively-
coupled plasma--mass spectrometry indicated particles in the dust and 
fume range. While the range of inside- and outside-the-facepiece 
concentrations were presented, individual inside and outside 
concentrations or results by employee or job classification were not 
provided. Similarly, the report presented an overall GM WPF, GSD, and 
fifth percentile WPF, but not individual WPFs. Of the 55 sample 
measurements, 34 of the inside-the-facepiece results were below the 
analytical limit of detection. In these instances, the authors used a 
conservative WPF calculation by setting the values at the limit of 
detection. No lead was detectable on the field blanks so no adjustments 
were made to sample weights. The authors do not mention adjusting 
inside-the-facepiece values for pulmonary particle retention. Final 
calculations used only those sample pairs with outside sample weights 
greater than 1,000 times the detection limit. The authors believed this 
procedure was necessary to determine that the respirator was capable of 
providing a protection factor of 1,000. The authors also analyzed the 
data for outliers (at the 99% confidence level). The overall data 
analysis resulted in a GM WPF of 8,843, a GSD 3.2, and a fifth 
percentile WPF of 1,335. The authors concluded that the data supported 
ANSI's proposed APF of 1,000 for full facepiece PAPRs. They also 
recommended that fit testing be performed on all tight-fitting 
respirators.
5. WPF Study--Helmet/Hood PAPRs
    Study 27. At the 1990 AIHCE, D.R. Keys, H.P. Guy, and M. Axon 
reported on a 3-month WPF study in which they evaluated exposure to 
estradiol benzoate (a steroid) for an unspecified number of workers in 
a pharmaceutical facility (Ex. 64-40). They included three loose-
fitting hood/helmet type PAPRs in the study: Racal Breathe Easy 10, 
Bullard Quantum, and 3M Whitecap II. All three PAPRs had double-bibbed 
capes, were equipped with HEPA filters, and did not have lift-up 
visors. A Tyvek hood was part of the Racal and Bullard PAPRs while the 
3M had a hard helmet. PAPRs were previously used at the facility, so 
workers were already properly trained in their use and were familiar 
with wearing them. The investigators observed the participants 
continuously, one-on-one, during sampling. While the authors used field 
blanks, they did not mention determining particle size or using a clean 
area for donning and doffing or for starting and stopping the sampling 
train.
    The inside- and outside-the-facepiece sampling trains consisted of 
a 37 mm two-piece cassette with a glass fiber filter, attached to a 
nylon Liu probe. Location of the inside-the-facepiece probe was not 
specified. Samples were gathered for \1/2\-3 hours at a flow rate of 
2.5-3.5 Lpm. Pumps were calibrated in-line before and after each 
sampling period.
    The authors used radioimmunoassay (RIA), a very sensitive 
analytical technique, to analyze inside-the-facepiece samples, and HPLC 
to analyze outside samples; they rejected inside samples with weights 
below the limit of quantification. Also, the investigators rinsed the 
outside sample probes with methanol and analyzed the rinsate by HPLC to 
determine sample loss due to probe use. The authors did not provide any 
further analytical information.
    Sixty valid sample sets were obtained from the study. Results were 
not adjusted for blank value (i.e., all blank values were below 1 
nanogram per filter) or probe loss (i.e., the GM of 1% was not 
statistically significant). Individual inside and outside 
concentrations or WPFs were not reported. Instead, the authors 
presented the range of inside- and outside-the-facepiece 
concentrations. They determined an overall fifth percentile WPF for 
each respirator, along with the number of samples, the minimum and 
maximum WPF achieved, a GM WPF, and the GSD. In addition, the authors 
determined the percentage of WPFs that fell in selected ranges (e.g., 
<1,000, 1,000-10,000) for each PAPR, and they briefly discussed the 
correlation between WPF and outside concentration (i.e., they found WPF 
to be independent of outside filter loading in this study). The Racal 
Breathe Easy 10, with 29 sample pairs, had a GM WPF of 11,137, a GSD of 
3.9, and a fifth percentile WPF of 1,197. The Bullard Quantum, with 9 
sample pairs, had a GM WPF of 9,574, a GSD of 3.1, and a fifth 
percentile WPF of 1,470. The 3M Whitecap II helmet, with 22 sample 
pairs, had a GM WPF of 42,260, a GSD of 9.8, and a fifth percentile WPF 
of 997. The authors stated that they obtained WPFs above 10,000 for the 
three PAPRs at least 44% of the time, and that the three respirators 
provided WPFs above 1,000 throughout the study. The authors concluded 
that the results of their study agreed with the then-proposed ANSI 
Z88.2-1992 APF of 1,000 for PAPRs with hoods or helmets.
6. WPF Studies--Loose-Fitting Helmet/Hood PAPRs & Loose-Fitting 
Facepiece PAPRs
    Study 23. W.R. Meyers, M.J. Peach, K. Cutright, and W. Iskander 
reported in 1984 on a study in which they examined lead (Pb) exposure 
of 12 workers in a secondary lead smelter (Ex. 1-64-47). The job 
classifications studied were furnace operator, helper,

[[Page 34062]]

and pig caster. They selected two employees from each classification on 
two shifts. The PAPRs used in the study were the 3M W-344 and the Racal 
AH3; each employee wore both respirators twice. Pre-shift quantitative 
fit testing was performed each day. The investigators trained the 
participants, but did not describe the training; they monitored the 
employees continuously during sampling.
    The authors referred to a companion paper for a description of the 
sampling protocol used in this study; therefore, they provided no 
information is provided on sampling or analytical methodologies in this 
report. Eight impactor samples were collected at each work activity to 
determine particle size distribution. Samples were collected for the 
full shift, but the investigators did not provide specific sampling 
times. The authors also provided the range of inside-the-facepiece 
concentrations, with associated GM and GSD, for both brands of 
respirator; they measured these concentrations with the PAPRs placed on 
manikins which were located at the worksites where employees in the 
three job classifications worked.
    For each respirator, the study provided 24 individual inside- and 
outside-the-facepiece (front and rear) concentrations, along with 
associated WPFs and each employee's fit factor. It also provided the 
overall GM, GSD, and 95% confidence level on the mean for the inside-
the-facepiece concentrations, WPFs, and fit factors. The authors 
tabulated the data by day, shift and work activity. For both 
respirators, two samples were discarded due to sampling pump failure, 
giving 22 usable measurements for each respirator. The WPFs measured on 
the Racal AH3 ranged from 42 to 2,323, with a GM of 205 and a GSD of 
2.83. The 3M W-344 had WPFs that ranged from 28 to 5,500, with a GM of 
165 and a GSD of 3.57. The two-sided 95% confidence limits around the 
mean of the WPFs were 128 and 325 for the Racal AH3, and 94 and 292 for 
the 3M W-344. The authors provided a detailed discussion of their 
statistical analyses of the data; they also discussed several potential 
sources of variation in the workplace performance of PAPRs, including: 
a possible relationship between fit factor and WPF; a possible 
relationship between fit factor and inside-the-facepiece concentration; 
day of the week; shift; leakage into the facepiece due to ambient air 
currents; and worker activity. The only sources found to be potentially 
significant were leakage into the facepiece due to ambient air currents 
and worker activity. The authors stated that ``* * * using the pooled 
3M and Racal WPF data and a probability of 0.95 the assigned protection 
factor calculated by this method for these PAPRs would be 26.'' They 
recommended a reduction in the RDL's APF of 1,000 for loose-fitting 
PAPRs with helmets and HEPA filters.
    Study 5. W.H. Albrecht, G.R. Carter, D.W. Gosselink, H.E. Mullins, 
and D.P. Wilmes reported at the 1986 AIHCE on a study they conducted 
that evaluated protection against exposure to asbestos fibers for 12 
workers who manufactured asbestos-containing brake shoes for trucks 
(Ex. 1-64-23). The employees performed six operations at the facility: 
mixing brake shoe components, weighing mixed formulation, pre-forming 
molding press charges, molding the shoe, grinding the brake shoe 
surface, and drilling shoe mounting holes. The investigators sampled at 
each operation. The PAPR studied was the 3M Airhat with high-efficiency 
(HEPA) filters. The participants and supervisory staff were shown an 
audio slide presentation explaining how to fit respirators and the 
procedures for saccharin fit testing; they then received the saccharin 
qualitative fit test (since the authors do not specifically mention fit 
testing the PAPR, it is assumed that only the half-mask respirators 
studied were fit tested). Fit testing was not conducted prior to each 
study test. The PAPR was fitted and worn according to the 
manufacturer's instructions. Each employee was observed on a one-on-one 
basis during testing to assure that they properly donned and used the 
respirator and that sampling train integrity was maintained.
    The inside-the-facepiece sampling train was a closed-face filter 
cassette connected to a tapered Liu probe, inserted into the respirator 
between the nose and mouth. The outside-the-facepiece sampling train 
was a closed-face filter cassette connected to a Liu probe attached in 
the employee's lapel area; the authors do not mention cassette size. 
Samples were collected for 30 minutes, but other sampling times were 
occasionally used; sampling pump flow rates were 2 Lpm (inside-the-
facepiece) and 0.5 Lpm (outside-the-facepiece). The report does not 
mention modifying the inside-the-facepiece probe location (midway 
between the nose and mouth) or the sampling flow rate for the PAPR 
versus that used for the half-mask respirators studied.
    Sampling trains were calibrated before the shift, at lunch, and at 
the end of the shift; average airflow rate was used to calculate 
sampled air volume. The investigators did not mention determining the 
PAPR's airflow rate.
    Asbestos analysis was based on NIOSH method 7400, with 500 fields 
counted per inside sample filter and 100 fields counted per outside 
sample filter. The distributions of fiber length and fiber diameter 
were not characterized. The authors stated that blanks were submitted 
for fiber counting; however, no further mention is made of the blank 
results or how they were addressed. None of the PAPR samples were 
comparison counted by Phase Contrast Microscopy (PCM) and Scanning 
Electron Microscopy (SCM). A total of seven PAPR WPFs were reported (5 
employees). Individual pairs of inside and outside concentration values 
were not provided. Individual WPFs were reported for each of the seven 
sampling intervals, but were not linked to specific participants or 
jobs. The authors provided an overall GM, GSD, and fifth percentile for 
the Airhat PAPR; a range of asbestos concentrations and the associated 
GM and GSD were also reported by job. An inside-the-facepiece fiber 
count of 1,000 was used in calculating the WPF when the sampling result 
was at or below the limit of detection (i.e., 1,000 fibers per filter). 
The investigators did not mention adjusting inside-the-facepiece values 
for fiber retention in the respiratory tract. In addition, the authors 
determined that sampling results were not affected, at the 95% 
confidence level, by sampling flow rate or open-versus closed-face 
sampling cassette. The mean breathing zone concentration of asbestos 
for the Airhat PAPR was 4.14 fibers/cc, with a mean breathing zone 
concentration range of 1.23 to 8.05 fibers/cc. The authors reported a 
GM WPF for the PAPR of 199, with a GSD of 2.36 and a fifth percentile 
of 42. Five employees tested the PAPR, resulting in a total of nine 
sample sets, including two unusable sets of data. The authors noted 
that respirators that had the highest GM and fifth percentile WPFs 
(i.e., the 3M Airhat and 3M 9920 DFM respirators) were also tested at 
higher breathing zone fiber concentrations. They believed that this 
factor probably led to these respirators' increased performance 
measurements.
    Study 22. In 1986, W.R. Meyers, M.J. Peach, K. Cutright, and W. 
Iskander reported on a study in which they evaluated exposure to lead 
(Pb) dust and mist for 12 workers on two lead acid plate production 
lines of a battery manufacturer (Ex. 1-64-48). They sampled the pasting 
operator and two slitter operators on each line for two different 
shifts. The respirators studied were the Racal Airstream AH5 and the 3M 
W-3316, equipped with a helmet, visor enclosure, and dust/mist filters. 
Participants were clean-shaven, and

[[Page 34063]]

each employee wore both types of respirator twice. The AH5 provided a 
seal between the employee's face and the face shield by using two 
flexible face seals; air was exhausted at the chin. The size of the 
faceseal (i.e., large or small) was selected based on the appearance of 
best fit and wearer comfort. The 3M's soft flexible face seal gave a 
loose-fitting seal between the face and face shield, with air exhausted 
at the temples. Prior to field testing, randomly-selected filters 
underwent silica dust penetration testing. The investigators put on and 
removed the respirators from the employees in a clean area, except when 
the employees took personal breaks (in which case, the employees donned 
and doffed the respirator in the work area). Employees were not fit 
tested, but were instructed in the proper use of the PAPR and directed 
not to remove the helmet, lift the face shield, or tamper with the 
sampling equipment without notifying the investigators. The 
investigators continuously monitored donning and doffing and work 
activities. Respirator helmets and visors were cleaned between each 
use, and volumetric air output was periodically checked (usually at the 
beginning of the shift, lunch, and shift's end). The authors replaced 
the batteries according to manufacturer's instructions, and when low 
airflow occurred. They also installed new filters at the beginning of 
each shift. The investigators started the sampling pumps after the 
employees donned the respirators and the PAPR blower was functioning; 
they stopped the pumps before turning off the PAPR blower.
    Sampling trains were identical and consisted of a closed-face 37 mm 
two-piece cassette, containing a 0.45 micron pore size cellulose ester 
filter and back-up pad. Inside-the-facepiece sample cassettes were 
attached directly to a modified Luer adapter sampling probe, inserted 
through the face shield about one to two inches in front of the 
employee's mouth. Outside-the-facepiece sample cassettes were located 
at the front lower right side of the facepiece, away from the PAPR's 
exhaust airflow; they located a second cassette located the employee 
near the PAPR's filter, to determine the filter's contaminant 
challenge. All samples were collected as total dust at a flow rate of 
approximately 2 Lpm over the full shift (The report did not provide 
actual sample times). Sampling pumps were calibrated in the laboratory, 
and the flow rates confirmed at the worksite. Performance of the PAPR 
filtration system was checked by placing operating respirators on 
manikins (without simulated breathing), located about 4 feet from the 
subjects. Two filter blanks were used for each shift. Particle size 
distribution was determined through using a Marple cascade impactor 
operating at a flow rate of 3 Lpm.
    Inside-the-facepiece samples were analyzed by graphite furnace 
using a modified NIOSH P&CAM 214 method, with perchloric acid in the 
wet ashing step. Outside-the-facepiece samples were analyzed by atomic 
absorption spectroscopy (NIOSH Method S-341 with the perchloric acid 
wet ashing step modification). Forty-seven individual inside- and 
outside-the-facepiece (i.e., front and rear) time-weighted-average 
(TWA) measurements, with associated TWA WPFs, were provided (AH5 = 24; 
W-316 = 23). These results were tabulated by day, shift, and work 
activity. Overall GM and GSD were also given for the concentration 
measurements and WPFs. All blanks were below the analytical limit of 
detection; the authors did not mention adjustments for pulmonary 
retention. Particle size (large) and stationary manikin filter 
efficiency (98%-99.9%) were briefly discussed. The WPFs for the Racal 
AH 5 ranged from 23 to 1,063, with a GM of 120 and a GSD of 2.64. The 
WPFs for the 3M W-316 ranged from 31 to 392, with a GM of 135 and a GSD 
of 1.89. Since the authors found no statistical difference between the 
performance of the respirators, they pooled the data for both 
respirators; they then graphically plotted the percent of WPFs less 
than specific values. The pooled data for the two PAPRs resulted in a 
distribution with a GM of 127 and a GSD of 2.28. The authors stated 
that, at a 0.95 probability level, this class of PAPRs would receive an 
assigned protection factor of 25. The authors also stated that the 
results ``* * * strongly suggest that the respirator user community not 
view current generation powered air-purifying respirators equipped with 
helmets as positive pressure respiratory devices.''
    Study 3. A. Gaboury and D.H. Burd (Ex. 1-64-24) and A. Gaboury, 
D.H. Burd, and R.S. Friar (Ex. 1-64-348) reported in 1993 on the WPF 
study they performed in a primary aluminum smelter. Exposure to 
benzo(a)pyrene [B(a)P] on particles was measured for 22 employees who 
worked as rack raisers, stud pullers, and rod raisers on anode crews. 
The employees used a Racal Breathe-Easy 1 (BE1/AP3), a loose-fitting 
helmeted PAPR. The PAPR came equipped with one-piece non-woven flame-
retardant face seals, visor locking clips, and combination organic 
vapor and HEPA filters. (The authors also tested the performance of 
several negative-pressure, air-purifying half-mask respirators; see 
Study 7 above). The employees previously received training on this 
PAPR, and used it for more than six months prior to the study. Forty 
percent of the employees had beards (i.e., more than two weeks growth), 
but the investigators did not find a significant difference between 
bearded and non-bearded participants. No fit testing was performed on 
the employees, but previous quantitative fit testing showed fit factors 
``greater than 1000 in all cases.'' Industrial hygiene technologists 
assisted participants with donning and doffing respirators, cleaned and 
maintained the respirators at the end of each work cycle, and observed 
participants on a one-to-one basis throughout the sampling period. The 
investigators directed the employees not to tamper with the respirator 
or sampling equipment. Due to high heat levels in the work area, the 
employer required employees to rest in a cool environment for one-half 
hour during each work hour.
    The inside-the-facepiece sampling train consisted of a closed-face 
three-piece cassette with a 25 mm organic-binder-free glass fiber 
filter, backed with a cellulose ester pad. Inside sampling cassettes 
were connected to a tapered Liu probe, which was inserted through the 
PAPR's visor and into the employee's breathing zone. The outside-the-
facepiece sampling train was identical to the above; however, the 
investigators did not mention connecting the cassette to a Liu probe. 
The outside cassette was mounted on a bracket at the top of the visor. 
All filters were pre-calcined at 400 degrees Centigrade for 24 hours. 
Both inside and outside samples were collected at a flow rate of 2 Lpm 
for approximately 300 minutes, or one-half of the 10-hour work shift. 
Respirators and sampling trains were worn and operated until the 
employee entered the rest area; they donned and turned on the 
respirators prior to leaving the rest area for the next work cycle. The 
authors plugged the sampling cassettes when not in use, and cleaned the 
respirators after each work cycle. Field blanks were used to identify 
contamination due to handling. Sampling train airflow rates were 
checked at the beginning, middle (i.e., after lunch), and end of the 
work day; upon changing cassettes; and when a problem was suspected. 
PAPR turbo-unit flow rate was checked every two hours to assure flow 
was greater than six cubic feet per minute (cfm). Sampling occurred 
over a five-day period.

[[Page 34064]]

    B(a)P analysis followed Alcan Method 1223-84. The ambient 
B(a)P particle size distribution was determined by collecting four 
samples, as close as possible to the workers, using an 8-stage Anderson 
cascade impactor (Model 296). Impactor samples were collected for two 
to five hours at a flow rate of 2 Lpm. The average percent of B(a)P 
mass (across four samples) per impactor stage (defined by an 
aerodynamic diameter cut point, in micrometers) was reported. About 93% 
of the B(a)P mass was associated with particles having diameters of 
<=9.8 micrometers. A total of 20 pairs of inside and outside sample 
concentrations, with associated WPFs, were provided by job category 
(but not for individual employees), and whether the employee had a 
beard. An overall GM, GSD, and 95% confidence interval on the mean were 
also provided for the inside and outside concentrations and WPFs, along 
with an overall fifth percentile WPF. The authors stated that some 
employees participated more than once during the study. They did not 
mention adjusting inside-the-facepiece values for particle retention in 
the respiratory tract. The authors found no significant relationship 
between B(a)P concentrations inside and outside of the facepiece, but 
they did find a correlation between WPF and outside B(a)P 
concentrations. The authors stated that, while the data were limited, 
they recommended testing PAPRs at relatively high concentrations to 
obtain an accurate measure of their performance. The inside B(a)P 
concentration ranged from 0.006 to 0.072 [mu]g/m3, with a GM 
of 0.012 [mu]g/m3. The outside B(a)P concentration ranged 
from 246 to 111.48 [mu]g/m3 with a GM of 16.73 [mu]g/
m3. WPFs ranged from 371 to 8658, with a GM of 1,414. The 
two-sided 95% confidence interval limits around the overall GM WPF were 
918 and 2,173; the fifth percentile was 275. The authors cautioned that 
these results WPFs achieved under conditions of good worker compliance 
and tight administrative control; however, without these conditions, 
WPFs may be less because: close surveillance of workers is not usually 
performed; cleaning during rest periods is not done prior to returning 
to the workplace; visor locking clips are not routinely used; and no 
respirator is used 100% of the time while in the workplace.
    Study 26. At the 2001 AIHCE, D.V. Collia, et al. presented a study 
on the workplace performance of a PAPR against exposure to cadmium (Cd) 
for seven workers, over three days, in a nickel-cadmium battery 
manufacturing facility (Ex. 3-5). The respirator studied was the 3M 
Breathe-Easy 12 (BE-12), a loose-fitting facepiece PAPR equipped with 
high-efficiency filters; the employees were using this PAPR prior to 
the study. During a preliminary visit, the investigators discussed the 
study with the union, management and workers. The authors also 
evaluated the worksite and took area samples to identify areas with the 
highest exposures. Prior to sampling, they informed the employees about 
their role in the study, as well as the study's purpose and procedures. 
The investigators continuously observed the employees during sampling, 
and used field blanks to identify contamination from handling. The 
study contained no additional information on sampling protocols (e.g., 
donning and doffing procedures).
    Inside-the-facepiece samples were gathered using 25 mm three-piece 
cassettes containing an unspecified membrane filter and a porous 
plastic back-up pad. A nylon Liu probe was used, and the samplers were 
positioned directly across from the midline between the employee's nose 
and mouth. Outside-the-facepiece samples used 25 mm three-piece 
cassettes containing an unspecified membrane filter, backed with a 
cellulose pad. Outside samples were positioned close to the employee's 
breathing zone (the investigators provided no further details). All 
samples were collected at 2 Lpm for approximately one and one-half 
hours (range: 67-156 minutes).
    Inside-the-facepiece samples and blanks were analyzed by flame 
atomic absorption spectroscopy and heated graphite furnace atomizer 
(AAS-HGA). Analysis of outside-the-facepiece samples was by AAS. The 
analytical methodology used OSHA's method for Cd in workplace 
atmospheres (OSHA ID-189). The authors provided the mean mass for 
inside and outside blanks, but made no mention of data adjustments for 
blanks or pulmonary retention. They also reported minimum and maximum 
concentrations of inside- and outside-the-facepiece samples for each 
employee. Supplemental data contained 41 individual measurements of 
inside and outside concentrations, tabulated by employee, job area, 
sample period and set, sample time, pump flow rate, and sampled air 
volume.
    WPFs were calculated for 33 of the sample sets (8 of the 41 inside-
the-facepiece samples had no detectable Cd). The calculated GM WPFs 
ranged from 1,460 to 9,440. The fifth percentile WPF was calculated in 
three different ways: the traditional approach yielded a fifth 
percentile WPF of 315; an analysis of variance (ANOVA) model, yielded a 
fifth percentile of 280; and the Monte Carlo simulation model approach 
resulted in a fifth percentile of 220 when the non-detected inside 
values had a value of 0.002, a fifth percentile of 303 with the non-
detected values excluded, and a fifth percentile of 103 with Employee C 
excluded. The authors concluded that the BE-12 PAPR provided a level of 
protection consistent with an APF of 25.
    Study 24. D.W. Stokes, A.R. Johnston, and H.E. Mullins determined 
exposure to silica (Si) dust for five workers in a roofing granule 
production plant (Ex. 1-64-66). The participants were involved in 
cleanup of silica dust byproduct by sweeping, brushing walls, and 
shoveling. The respirator studied was the 3M Airhat, a loose-fitting 
PAPR with helmet, equipped with dust/mist or high-efficiency filters, 
and worn with and without a Tyvek shroud. The investigators assisted 
the participants were assisted with donning the sampling equipment; 
however, they did not mention training the employees. They observed the 
employees during sampling, and used field blanks to determine the 
effects of handling on sample contamination. They did not mention 
determining the particle size of the contaminant.
    Inside-the-facepiece samples were collected through a Liu probe 
inserted into the faceshield (they did not provide the probe's specific 
location). A 25 mm cassette containing a 0.8 micron pore size 
polycarbonate filter was used, and sampling airflow rate was 1.5 Lpm. 
Outside-the-facepiece samples were gathered as both total and 
respirable dust. Respirable dust samples were collected at 1.8 Lpm 
using a 37 mm 0.8 micron pore size polycarbonate filter placed in a 
cyclone that attached to the employee's lapel. Total dust samples also 
used a 37 mm 0.8 micron pore size polycarbonate filter. Sampling 
airflow rate was 2 Lpm, with the sampling cassette attached to the 
employee's lapel. The investigators calibrated the sampling pumps each 
day, and checked proper airflow rate three times throughout the day. 
They collected samples over a four-day period, with sampling times 
ranging from 30 minutes to 1 hour. At the beginning and end of each 
sample, the authors confirmed that each PAPR's airflow rate was in 
excess of 6 cfm.
    The authors used proton induced x-ray emission (PIXE) to analyze 
the samples. They adjusted the inside- and outside-the-facepiece 
concentrations by subtracting the mean blank value, but did not mention 
adjustments for pulmonary retention of particles. They also did not 
provide individual inside-

[[Page 34065]]

and outside-the-facepiece concentrations and WPFs. They presented 
results in two tables showing respirable dust samples with values 25 
times the mean blank level, and total dust samples with values 100 
times the mean blank level. The investigators provided tables reporting 
sample size and overall GM, GSD, and fifth percentile WPF by type of 
filter (i.e., dust/mist, HEPA) and the presence or absence of a shroud 
(i.e., dust/mist with shroud, dust/mist without shroud). Using the 
respirable dust samples that were 25 times the mean blank value, the 
authors combined the sampling results of the PAPR with dust/mist 
filters (i.e., with and without a shroud) and found an overall GM WPF 
of 2,480 and a fifth percentile of 95. The combined respirable dust 
results of the HEPA-filtered PAPR gave an overall GM WPF of 5,730 and a 
fifth percentile of 762.

Atmosphere-Supplying (Supplied-Air) Respirators

    Atmosphere-supplying respirators, also referred to as supplied-air 
respirators (SARs) or airline respirators, operate in one of three 
modes: Demand, continuous flow, and pressure demand. Demand and 
pressure demand respirators can be equipped with half or full 
facepieces. Continuous flow respirators can also be equipped with a 
helmet, hood, or loose-fitting facepiece.
7. WPF Studies--Loose-Fitting Atmosphere-Supplying Respirators With 
Hood or Helmet
    Study 28. A.R. Johnston, et al. in 1987 conducted a WPF study 
evaluating exposure to silica (Si) among four shipyard workers who wore 
a 3M Whitecap II loose-fitting, continuous flow SAR with hood/helmet 
while sandblasting paint from the flat top of a barge (Ex. 1-64-36). 
The respirator was comprised of a W-8100 abrasive blasting helmet, a W-
5114 breathing tube, a W-2862 air / temperature control valve, 50 feet 
of W-9435 air hose, and a W-8054 extended length shroud. To permit 
evaluation of the respirator at its low and high range of airflow 
rates, air pressure was maintained at 60 or 80 psi, resulting in an in-
helmet airflow rate of either 6.4 or 14.4 cfm. The investigators 
informed the employees of the purpose and protocols of the study, and 
instructed them in the proper donning and use of the respirator. They 
also directed the employees not to adjust or remove the respirator 
after sampling began. Sampling trains were connected and disconnected 
in a clean area when possible. Sampling pumps were started after 
confirming proper operation and donning of the respirator, as well as 
airflow rate into the helmet. Pumps were stopped before the helmet was 
disconnected from the air supply and removed. The authors maintained 
continuous one-on-one observation of the employees during sampling, and 
used several field blanks during each day of sampling.
    The authors collected inside-the facepiece samples on 25 mm 
cassettes containing 0.8 micron pore size polycarbonate membrane 
filters. They attached the cassettes directly to a Liu probe inserted 
through the center of the faceshield, about midway between the nose and 
mouth; the probe extended about 3 mm into the helmet. The flowrate for 
the inside samples was approximately 2 Lpm. The authors collected 
outside-the-facepiece samples as both total and respirable dust, using 
a 37 mm cassette with a 0.8 micron pore size polycarbonate membrane 
filter. They used a Bendix or SKC cyclone, operating at 1.7 Lpm airflow 
rate, to gather the respirable dust samples and obtained total dust 
samples at flow rates ranging between 0.5 and 2 Lpm. Both outside-the-
facepiece sample cassettes were located on the employee's lapel. The 
investigators calibrated the sampling pumps at least three times a day, 
and sampling periods ranged from 10 to 60 minutes to prevent filter 
overloading.
    The authors analyzed all samples using PIXE. They found Si on all 
18 blanks. Of 68 initial sample sets, they discarded 16 (11 due to test 
malfunctions and 5 due to outside loadings less than 10 times the mean 
blank level and inside loadings at or below the blank level). They 
corrected the remaining 52 sample sets for blank value, and then 
tabulated by inside and outside filter weights, inside and outside 
sample volume, and associated WPFs. Since nearly all of the dust was of 
respirable size, the authors did not report results for the total dust 
samples. Comparing the sampling results with the mean blank levels, the 
investigators stated that the analytical confidence limits of the data 
were poor, with only 11 samples being better than plus or minus 25%. 
The authors considered samples with inside concentrations greater than 
1,000 times the mean field blank to be an accurate indicator of the 
respirator's performance capability; seventeen sample sets met this 
criteria, but they removed two samples WPF calculation database as 
outliers. For the remaining 15 samples, the GM WPF was 4,076, the GSD 
was 2.3, and the fifth percentile WPF was 1,038.
    The authors concluded that WPFs generated from sample sets with 
light outside dust loadings significantly underestimated respirator 
performance; higher outside sample loadings appeared to be less 
influenced by non-respirator variables. The investigators judged WPF 
estimates derived from data subsets with higher outside filter loadings 
as providing a better indication of respirator performance capability. 
The authors also discussed an apparent correlation between WPFs and 
outside filter loadings (i.e., a higher loading equaled higher a WPF 
until reaching a plateau about 600 times the mean blank value); 
however, the correlation between WPFs and outside concentrations was 
not statistically significant. In addition, the effect of higher versus 
lower helmet airflow rate on sample results and WPFs was not 
significant. They also discussed the daily and overall WPFs achieved 
when using time-weighted-averages for the calculations. They concluded 
that their data supported the ANSI Z88.2 proposed APF of 1,000 for 
loose-fitting SARs with hoods or helmets.
    Study 20. At the 1989 AIHCE, A.R. Johnston, C.E. Colton, D.W. 
Stokes, H.E. Mullins, and C.R. Rhoe presented a WPF study on a 3M W-
8000 Whitecap II SAR with a helmet, and equipped with a breathing tube 
(W-5114), a compressed air hose (W-9435), and either a vortex cooling 
assembly (W-2862) or air regulating valve (W-2907) (Ex. 1-64-37). They 
evaluated exposure to iron (Fe) dust and silicon (Si) dust for six 
workers involved in grinding iron parts at a foundry. Air supply 
pressure was 60 psi with the vortex cooler or 25 psi with the 
regulating valve, thereby maintaining a helmet airflow rate of 6.7 cfm 
throughout the test. They did not mention employee selection 
procedures, previous use of respiratory protection, provision of 
training, or respirator donning and doffing procedures. They verified 
air supply pressure; valve settings; and integrity of the respirator, 
connections, and sampling train before starting the sampling pumps. 
They stopped the samplers before disconnecting the respirator from the 
air supply; they then took the participants to a clean area to remove 
the sampling cassette. The investigators observed the employees on a 
one-on-one basis during sampling, and used field blanks to evaluate 
possible contamination due to sample handling.
    The inside-the-facepiece sampling train consisted of a 25 mm 
cassette containing a 0.8 micron pore size polycarbonate filter. The 
authors attached the cassette to a Liu probe installed into the 
faceshield approximately midway between the nose and mouth; it extended 
a few millimeters into the helmet. They

[[Page 34066]]

collected inside-the-facepiece samples at an airflow rate of 2 Lpm. The 
outside-the-facepiece sampling train also used 25 mm cassettes 
containing 0.8 micron pore size polycarbonate filters. The 
investigators collected outside samples as respirable dust using a MSA 
or Bendix cyclone operating at an airflow rate of 1.7 Lpm; however, 
they did not mention the location of the outside sample cassette. They 
collected area samples for particle size analysis using cellulose 
acetate filters and a personal sampling pump operating at 2 Lpm. They 
calibrated the sampling pumps at least three times a day, but did not 
mention specific calibration times.
    The authors analyzed the samples for Fe and Si using proton induced 
x-ray emission (PIXE) analysis. Having detected Fe and Si on the field 
blanks, they used the mean blank value to correct inside- and outside-
the-facepiece sample weights. They used optical microscopy to determine 
mean particle size range from 6 area samples. The investigators 
presented no data for individual inside- and outside-the-facepiece 
concentrations, and associated WPFs; however, they did provide the 
range of outside sampling measurements, and the overall average outside 
concentration, for both analytes. While they presented the range of 
inside-the-facepiece concentrations, they did not report the average 
inside concentrations. Outside samples averaged 1,500 [mu]g/
m3 for iron dust, and ranged from less than 100 to 2,800 
[mu]g/m3. Outside samples for silicon averaged about 1,000 
[mu]g/m3, with a range from less than 100 to 1,500 [mu]g/
m3. Inside concentrations were at or near the detection 
limits for both elements. For the 39 samples with values greater than 
25 times the field blank, the authors reported a GM WPF of 273, a GSD 
of 5.7, and a fifth percentile of 39. For samples with outside filter 
weights greater than 750 times the field blank, they reported a GM WPF 
of 1,012, a GSD of 2.6, and a fifth percentile of 199. The 
investigators found a significant correlation between mean filter 
weights and WPFs; this correlation did not plateau at higher filter 
loadings. The authors stated that their measurements never reached a 
level at which the protection factors were independent of the outside 
filter weight. They concluded that the relatively low sample loadings 
resulted in WPFs that significantly underestimated the respirator's 
performance. They stated that, in the case of SARs, the researchers:

    * * * should attempt to target outside loadings of at least 1000 
times the anticipated analytical detection limit. If we do not, the 
data we get is likely to reflect limitations of our sampling and 
analysis procedures, rather than the respirators we are testing.

    Study 19. At the 1993 AIHCE, C.E. Colton, H.E. Mullins, and J.O. 
Bidwell of 3M presented a WPF study on the 3M Snapcap W-3256 airline 
respirator (TC 19C-70) with a loose-fitting hood, fitted with a W-3258 
hard hat, W-5114 breathing tube, W-2862 vortex tube air regulating 
valve, and 50-100 feet of W-9435 compressed-air hose (Ex. 1-64-17). 
They measured exposure to silica (Si) for four workers involved in 
furnace teardown at a foundry. The respirators were operated at an air 
pressure of 75 psi, with the participants were permitted to regulate 
the airflow rate to a comfortable level. The authors later determined 
that this level was 8-9 cfm. The job task consisted of using pneumatic 
chippers to remove the furnace wall and bottom. Pieces of wall and 
bottom either fell into or were shoveled into a barrel for removal. The 
employees then vacuumed of the furnace bottom. The job consumed most of 
the eight-hour shift. Since the furnace was warm and the work was 
physical, the employees worked in pairs for about one hour before 
switching with other employees; therefore, sampling times varied over 
the two separate days of the study. Participants normally wore air-line 
respirators. The investigators informed them of the study's purpose, 
procedures, and their role, and provided them with instruction on the 
proper donning, fitting, and operation of the respirator; however, the 
authors did not mention fit testing the participants. The investigators 
observed the employees on a one-on-one basis during sampling. The 
employees donned and doffed the respirators and sampling trains in a 
clean area, and the investigators checked the integrity of the 
respirator and sampling train before the respirator was connected to 
the air supply. The authors started the sampling pump after connecting 
the respirator to the air line, and stopped the pump before 
disconnecting the respirator from the air supply. They used field 
blanks to evaluate the possibility of contamination from handling the 
samples.
    Inside- and outside-the-facepiece samples were collected in 25 mm 
three-piece cassettes containing 0.8 micron pore size polycarbonate 
filters and porous plastic back-up pads. Inside-the-facepiece cassettes 
were attached to the inside of the hood, directly across from the 
employee's mouth, with the cassette pointed toward the employee. A 
nylon Liu probe was attached to the inside cassette, and a sample line 
ran through the elasticized inner shroud and out to the sampling pump; 
the inside sampling flow rate was 2 Lpm. Outside-the-facepiece samples 
were collected as respirable dust through use of a 10 mm nylon cyclone; 
the outside sampling flow rate was 1.7 Lpm. The authors do not mention 
the location of the outside sampling cassettes, or what method they 
used to conduct particle size sampling.
    The investigators used PIXE to analyze collected samples for Si; 
however, overloading of many of the outside-the-facepiece samples 
prevented PIXE analysis, requiring analysis of these samples by 
Inductively Coupled Plasma (ICP) spectroscopy. The authors made no 
field blank adjustments to the measured sample weights (i.e., Si was 
not detected on the field blanks). The investigators intended to 
invalidate sample pairs with an outside filter weight less than 1,001 
times the field blank value, or limit of detection if the field blank 
value was zero; all outside sample weights were more that 10,000 times 
the detection limit. In addition, they rejected sample pairs with 
inside sample weights that were less than the mean blank value. They 
did not mention correcting inside-the-facepiece values for pulmonary 
retention of particles, or how they managed sample results that were 
below the analytical detection limit. Particle size analysis showed the 
contaminant to be ``a dust with over 50 percent of the mass greater 
than 10 [mu]m.'' The authors established a correlation between the PIXE 
and ICP analytical methods by analyzing 37 samples using both methods. 
They developed a linear regression equation that permitted PIXE 
equivalents to be predicted from the ICP results. They reviewed the WPF 
results using: The ICP results for the outside concentrations, and PIXE 
results for the inside concentrations; and the regression to predict 
PIXE equivalents for the outside concentrations, and PIXE results for 
the inside concentrations.
    The authors calculated WPFs and checked the resulting values for 
outliers at the 99% confidence level. They did not provide individual 
inside- and outside-the-facepiece concentrations, but instead reported 
an overall range of inside and outside concentrations, along with the 
ranges' associated GM and GSD. In addition, the authors did not provide 
individual WPF values, but presented calculated WPFs as an overall 
fifth percentile WPF, GM, and GSD for each of the 2 days, based on both 
methods discussed above (i.e., ICP and PIXE equivalent). They found 
that the two methods gave similar results. Using the equivalent PIXE 
values (i.e., calculated from ICP values), and the

[[Page 34067]]

PIXE in-facepiece values, the GM WPF was 10,344, the GSD was 2.5, and 
the fifth percentile WPF was 2290. The authors stated that the loose-
fitting hood performed differently than a loose-fitting PAPR, and this 
difference should be reflected in the APF assigned. In addition, they 
briefly discussed a comparison of the study results with the results of 
several other PAPR and air-line respirator studies.
    Study 25. In 2001, T.J. Nelson, T.H. Wheeler, and T.S. Mustard 
published a WPF study of a supplied-air hood (Ex. 3-6). They measured 
exposure to strontium (Sr) for 19 painters and helpers involved in 
sanding and painting operations on several types of aircraft. They 
judged the work rate to be light to moderate. Prior to sampling, they 
informed the employees about the study, and instructed them to remain 
connected to the air supply during calibration and sampling. The 
participants used a 3M H-422 series supplied-air hood, equipped with an 
outer bib with an inner shroud and hard hat, H-420 hood, W-3258 hard 
hat, W-2878 suspension, 50 feet of W-9435 hose, and either the W-2862 
vortex cooling assembly or the W-2863 vortex heating assembly. The 
investigators regulated the supply air pressure to between 60 and 80 
psi. Employees donned the hoods in the work area, but investigators did 
not attach the sampling cassettes until after the employees connected 
the hood to the air supply and airflow began. They used field blanks to 
identify possible contamination due to handling, storage or shipment. 
In addition, they used manufacturer's blanks to detect contamination 
from manufacture of the filter, and a system blank to determine if 
contamination was present in the air supply.
    The investigators collected inside- and outside-the-facepiece 
samples using 37 mm or 25 mm three-piece cassettes containing mixed 
cellulose ester filters. The first 19 samples (i.e., collected during 
sanding) utilized 37 mm cassettes/filters, but half of the outside 
samples had no detectable Sr. To increase analytical sensitivity, they 
collected the remaining 18 samples with 25 mm cassettes and filters. 
Once the employee was connected to the air supply, they attached a 
sampling cassette inside the hood at a point midway between the nose 
and mouth, and to the side of the face. They then uncapped the cassette 
and connected a Liu probe to the cassette inlet. The authors placed the 
outside cassette in the lapel area and pointed it forward and down. 
They started the sampling pumps simultaneously, and performed in-line 
calibration. They collected samples at an airflow rate of 2 Lpm, for a 
period consisting of 2 hours for sanding and 90 minutes for painting. 
At the end of sampling period, they in-line calibrated the pumps, 
stopped the pumps, capped and removed the cassettes, and the employees 
disconnected and doffed the hood. They collected the system blank by 
mounting a cassette in an operating hood that was located away from the 
work area, and sampled air from inside the hood at 2 Lpm for 2 hours 
The authors did not mention making a particle size determination.
    The investigators analyzed the outside-the-facepiece samples and 
one of the manufacturer's blanks using NIOSH Method 7300. They used 
PIXE analysis for the inside-the-facepiece samples, field blanks, 
system blank, and the other manufacturer's blank. They tabulated the 
sampling results by date, activity, employee, sample time, inside and 
outside sampled volumes, inside and outside concentrations, and WPF. 
The authors reported thirty-one individual inside- and outside-the-
facepiece concentrations. However, the results of the outside samples 
obtained during sanding operations were only 30 times greater than the 
inside sample values. Therefore, the authors did not consider the data 
from the sanding operations to be a very useful indicator of respirator 
performance, and they did not calculate WPFs for the initial 19 sanding 
samples. Of the remaining 18 painting samples, they calculated WPFs for 
only 15 samples, after discarding 3 samples due to sampling errors. The 
Sr levels measured outside of the respirator ranged from 340 to 24,529 
[mu]g/m3, but the investigators found no detectable amounts 
of Sr on any inside-the-facepiece sample. Therefore, the authors could 
not directly determine WPFs for the respirator. However, they estimated 
WPFs by substituting the limit of detection for the inside 
concentration values. This procedure resulted in estimated WPFs that 
ranged from more than 920 to 52,000. The authors concluded that their 
study was ``* * * consistent with other simulated and WPF studies in 
that the ANSI Z88.2 WPF of 1000 is supported.''
8. SWPF Studies--Type CE Abrasive Blasting Respirators
    Bullard: 1995 LLNL Evaluation. During the development of the 
Interim Final Standard for Lead (Pb) in Construction (1926.25; 1996) 
and the Final Respiratory Protection Standard (63 FR 1152; 1998), the 
E.D. Bullard Company (Bullard) expressed concern about the APF of 25 
for Type CE respirators. The concern was that the interim final lead 
rule, as issued, went far beyond the HUD guidelines by assigning a 
different and lower protection factor to Type CE respirators than the 
HUD guidelines, which incorporated the general industry standard at 29 
CFR Sec.  1910.1025. Bullard maintained that its Model 77 and 88 
respirators provide much greater protection, and sought to have the APF 
for these models elevated to 1,000 in the Lead in Construction 
Standard. OSHA agreed to provide Bullard with the relief sought only if 
it contracted with an acceptable third party to design, monitor, and 
interpret the results of a simulated workplace study of these models 
under an appropriate and acceptable test protocol. As a condition for 
granting that relief, the study had to demonstrate that the abrasive 
blasting respirators achieved, at a minimum, a protection factor rating 
of at least 20,000 and maintained positive pressure throughout the 
testing.
    Bullard contracted with Lawrence Livermore National Laboratory 
(LLNL) which designed, conducted, and interpreted the results of the 
SWPF study, based on a protocol that was acceptable to OSHA. The LLNL 
informal report resulting from the testing indicated (based on 
computerized data backed up by strip chart recordings) that the two 
Bullard abrasive blast respirators achieved a minimum protection factor 
of 40,000 and maintained positive pressure throughout the testing.
    Therefore, the SWPF study conducted by LLNL demonstrated that, if 
used properly, the Bullard respirators were acceptable for lead 
exposures that are less than or equal to 1,000 times the PEL (50,000 
[mu]g/m3). In an August 30, 1995 memo to its Regional 
Administrators, OSHA recognized that the SWPF study results indicated 
that an APF greater than 25 was appropriate for the Bullard Model 77 
and Model 88 respirators, and the Agency granted these models an 
interim APF of 1,000 when used for lead in construction (Ex. 3-8-4; 
memo to RAs dated 8/30/95). However, the memo also noted that the 
Agency was aware of other data and at least one field study showing 
that in the workplace these respirators may provide considerably less 
protection when used in ways that do not conform to the manufacturer's 
specifications (e.g., the air supply hose is too long; the hose 
diameter is incorrect; the manufacturer's specified air pressure is not 
maintained) or that do not comply with the requirements of paragraphs 
(b), (d), (e) and (f) of 1910.134 (e.g., the respirator is not 
inspected frequently enough for

[[Page 34068]]

possible deterioration). The memo further stated that respirators will 
provide less protection than they are capable of, when used improperly 
(e.g., donning and doffing the respirators while still in containment; 
disconnecting the air hose prior to leaving the exposure area). In 
addition, these respirators are used in extreme conditions during 
construction activities (e.g., substantial and, sometimes rapid, 
deterioration caused by high-speed ``bounceback'' of the abrasive 
blasting material; very high levels of exposure). The impact of 
``bounceback'' on the integrity of the respirator was not evaluated in 
the LLNL SWPF study since the study challenge agent was a liquid, not a 
particulate (which is typically the type of contaminant found in 
workplaces). Also, because these respirators may, at times, be used 
near the limits of their protective capability, workers wearing these 
respirators in abrasive blasting operations could receive acute 
exposures if the respirators do not perform properly. Therefore, 
performance consonant with the elevated APF can only be assured when 
the respirators are properly used.
    As a result of the above, OSHA adopted a modified enforcement 
policy for these two respirators. This policy was limited to the Lead 
in Construction Standard (29 CFR 1926.62) and applied only to the 
Bullard Models 77 and 88. Also, the interim APF of 1,000 was pending 
until a final APF for this class of respirators could be determined 
through this rulemaking. Since OSHA believes that proper use of these 
respirators is imperative, the policy made it clear that the Agency 
would be very strict in assuring that these respirators are used in 
accordance with the manufacturer's specifications and the requirements 
of 1926.62.
    Clemco Apollo Models 20 and 60 and 3M Whitecap II. With the 
assistance of the Industrial Safety Equipment Association (ISEA), other 
respirator manufacturers of Type-CE, continuous-flow, abrasive blasting 
respirators covered by the Lead in Construction Standard were 
contacted. By participating in a similar study, these manufacturers 
were provided with an equal opportunity to obtain the same relief 
afforded to Bullard. The Clemco Apollo Models 20 and 60 and the 3M 
Whitecap II were tested under conditions similar to the Bullard Model 
77and 88 study. Based on the results of the studies, OSHA granted the 
respirators the interim APF of 1,000, and developed the same 
enforcement policy for Clemco (Ex. 3-7-4; memo to Regional 
Administrators dated 03/31/97) and 3M (Ex. 3-9-3; memo to Regional 
Administrators dated 12/08/98). Again, the interim APF was contingent 
on the final APF for these respirators being determined through this 
rulemaking.
9. SWPF Studies--N95 Air-Purifying Respirators
    NIOSH N95 Chamber Studies. In 1999, NIOSH conducted a chamber study 
of N95 respirators and statistically analyzed the respirators' 
performance (Ex. 4-14). The study involved twenty-five subjects meeting 
the criteria of the LANL respirator panel. Twenty-one respirators were 
tested and included twenty filtering-facepiece and one elastomeric 
half-mask. Each test involved a sequence of six sedentary-type 
exercises: Normal breathing, deep breathing, moving the head side to 
side, moving the head up and down, reading the rainbow passage out 
loud, and normal breathing. Each exercise took about 80 seconds. For 
all tests, the subjects donned the respirator and conducted a user seal 
check in accordance with the manufacturer's instructions. After each 
test, the test operator returned the respirator to its original pre-
test configuration (e.g., strap was loosened). The investigators used a 
PortaCount Plus, a condensation nucleus type of particle detector, to 
determine the protection factor by measuring both the challenge aerosol 
(i.e., ambient aerosol) and the aerosol penetrating the respirator.
    The total penetration of an aerosol into a respirator includes the 
penetration through the filter media in addition to that resulting from 
face seal leakage. To determine face seal leakage, the study authors 
subtracted estimated filter media penetration from the total observed 
penetration. Filter media penetration was ascertained by separate 
testing performed on the filter media after human subject testing. 
Testing was conducted at an airflow rate of 31.4 Lpm, as determined 
from a volume-weighted average cycle having a peak flow rate of 40 Lpm. 
The same penetration for a given media was subtracted from the total 
penetration for all subjects using a respirator with that media. 
Calculating face seal leakage in this manner assumes all subjects have 
the same constant, volumetric flow rate through the respirator. The 
authors also summarized total penetration and face seal leakage 
penetrations. The 95th percentiles presented by NIOSH were based on a 
formula using the geometric mean and geometric standard deviation, and 
assumes the distribution to be log normal.
    LLNL Study of Four N95 Filtering Facepiece Respirators. At OSHA's 
request, researchers at LLNL conducted chamber testing on four of the 
same commercial N95 filtering facepiece half-mask respirators used in 
the NIOSH study (Ex. 4-14). The four N95 filtering facepieces selected 
by OSHA for study were: 3M Model 8210, 3M Model 8511, Wilson Model 
9501, and MSA Affinity Ultra (formerly Uvex/Pro Tech Model 4010). Six 
subjects (three male, three female) with six different face dimensions 
(according to lip length) used each filtering facepiece. These subjects 
represented six different boxes on the Los Alamos National Laboratory 
half-mask test panel (Boxes 4, 5, 7, 8, 9, and 10). Subjects used the 
manufacturer's instructions prior to donning the respirator. Each 
subject tested each respirator 4 times, for a total of 16 tests per 
subject and 96 tests overall. The investigators probed the respirators 
in the area of the nose, using the TSI fit-test probe kit, and measured 
penetration values with a TSI PortaCount Model 8020. They used ambient 
room aerosol as the challenge atmosphere and monitored it continuously 
during testing with a second PortaCount. They used room aerosol at 
concentrations greater that 2,000 particles/cc. Subjects removed the 
filtering facepiece at the conclusion of each test and, after 
approximately 2 minutes, redonned the same unit. The test operator 
restored the respirator to pre-test configuration (e.g., straps were 
loosened) after each donning. Each test consisted of nine exercises: 
normal breathing, deep breathing, side-to-side head movement, up and 
down head movement, reading the rainbow passage, normal breathing, 
scooping rocks between buckets, stacking 30-pound concrete blocks and 
normal breathing. Subjects performed each exercise for 80 seconds, with 
a 20-second instrument purge cycle and 60 seconds of data collection 
per exercise.
    For each model of respirator, the investigators used the size that 
showed the least penetration when the subject performed a 60-second 
reading of the rainbow passage. This was a change from using the 
penetration measured during normal breathing (as done in the original 
NIOSH tests), and was chosen because reading is frequently found to be 
an exercise that permits high penetration. A 60-second normal breathing 
fit test was performed in addition to the reading fit test. Multiple 
fit tests (both reading and normal breathing) were performed, if 
necessary, to select a model size. Once fitted, each

[[Page 34069]]

subject completed four full nine-exercise tests.
    The NIOSH penetration results without fit-testing were compared to 
the LLNL test results. In general, the investigators found good 
agreement between the two studies, with the range of penetrations being 
similar in both studies. However, two differences were noted. For one 
model, (referred to by the researchers as Model D), the OSHA/LLNL study 
result indicated slightly more penetration than was observed in the 
NIOSH study. While the minimum penetration for Model D was 2 in both 
studies, the maximum penetration was 460 in the OSHA/LLNL study 
compared to 370 in the NIOSH study. However, both studies showed this 
respirator to be in the low performance range of penetrations. The 
researchers believed that this could be attributed to a poor-fitting 
individual that participated in the larger NIOSH study, but whose fit 
factor attributes were not represented by any participants in the 
smaller OSHA/LLNL study. They also noted that the design features of 
Model D, such as its folded shape and the plastic nose clip, may 
explain this respirator's poor performance. Furthermore, while this 
respirator was available in three sizes, it was very difficult to 
determine which size provided the best fit for several of the subjects.
    The LLNL penetration result for another respirator, referred to by 
the researchers as Model A, was slightly better than the NIOSH result 
for the same respirator. The LLNL researchers believed that the lower 
penetration they measured for Model A was possibly due to the 
difference in model size/fit selection criteria between the NIOSH tests 
and the LLNL tests (discussed above). Again, they felt that another 
possible reason could have been a poor-fitting individual in the larger 
NIOSH study that was not represented by the smaller OSHA/LLNL study.
    The LLNL researchers further investigated the apparent difference 
between the LLNL and NIOSH results for Model A. They found that 
eliminating subjects with poorly-fitting respirators significantly 
affects results. For example, a subject was started in the LLNL/OSHA 
test but was not tested because the investigators were unable to 
maintain a proper fit on the individual when using Model A (i.e., it 
fell completely off the nose of the subject upon donning). If tested, 
this subject or another less obvious subject who experienced poor fit, 
could have skewed the results of the LLNL/OSHA N95 evaluation 
significantly. The LLNL researchers believed that this latter analysis 
illustrates the potential influence of a single outlier on the overall 
results of a study. The advantages of controlled SWPF testing are 
apparent in this example.
10. SWPF Studies--PAPRs and SARs
    ORC Study on Respirators Used in the Pharmaceutical Industry. 
Before the publication of the final respiratory protection standard, 
Organization Resources Counselors, Inc. (ORC) raised an issue that had 
been the subject of discussions between ORC and OSHA for several years. 
In 1997, ORC and a group of its member companies sponsored a study of 
certain models of powered air-purifying and supplied-air respirators to 
evaluate the ability of these respirators to protect workers from 
exposures in the pharmaceutical industries. The study, ``Simulated 
Workplace Protection Factor Study of Powered Air Purifying and Supplied 
Air Respirators,'' (Ex. 3-4-1) was completed in 1998, and the initial 
results, along with detailed experimental data, were presented to OSHA.
    The experimental protocol used in the study was developed by the 
Organization Resources Counselors' respirator task force, LLNL 
investigators, participating respirator manufacturers, and 
representatives from NIOSH and OSHA. The study included a simulated 
workplace exercise protocol consisting of 12 exercises: normal 
breathing, twisting the head from side-to-side, moving the head up and 
down, touching toes, raising arms above the head, twisting at the 
waist, running in place, normal breathing, hand scooping of pebbles, 
normal breathing, building a concrete block wall, and normal breathing. 
Two exercises, hand scooping of pebbles and building a concrete block 
wall, were included to simulate tasks in the pharmaceutical industry. 
Seventeen subjects participated in the evaluation of five powered air-
purifying respirators (PAPRs) and six supplied-air respirators (SARs). 
Twelve tests were conducted for each respirator, with the study being 
performed in the LLNL respirator test facility.
    Input from OSHA resulted in two modifications to the protocol. It 
was decided that at least one of the three units for each respirator 
model tested would be purchased from the open market with the others 
being supplied directly from the manufacturer. A second change resulted 
from the Agency's interest in evaluating intra-personal variability in 
the performance of respirators. This was accomplished by testing one 
PAPR model and one SAR model during six wearings by a single 
individual. No significant difference in respirator performance was 
noted as a result of these modifications, and the overall results are 
presented below.
    The results of the ORC study indicated that although simulated 
workplace protection factors (SWPFs) greater than one million were 
recorded during some of these tests, a reporting limit of 250,000 was 
established as the highest value in which reliable facepiece leakage 
could be detected (limit of quantification). The median SWPFs for all 
respirators, except one SAR, were at or above the reporting limit of 
250,000. Lower fifth percentiles were above 100,000, with the exception 
of the one SAR. APFs were established for each of the 11 respirators by 
dividing the lower 5th percentile by a safety factor of 25. APFs ranged 
from 6,000-10,000 for PAPRs (including one loose-fitting PAPR), and 
3,000-10,000 for SARs, with the exception of one device. This SAR had 
lower 5th percentile of less than 20 and an APF of 1. Results are 
presented in the table below.

                                           Table 4.--Summary of Simulated Workplace Protection Factor Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                Device                             Range of SWPFs                          Median SWPF                       5th percentile SWPF
--------------------------------------------------------------------------------------------------------------------------------------------------------
PAPR 1................................  140,000-250,000            250,000                    250,000
PAPR 2................................  11,000-250,000             250,000                    170,000-210,000
PAPR 3................................  11,000-250,000             250,000                    250,000
PAPR 4................................  94,000-250,000             250,000                    246,000-250,000
PAPR 5................................  240-250,000                250,000                    150,000-230,000
SAR 1.................................  68,000-250,000             250,000                    250,000
SAR 2.................................  13,000-250,000             250,000                    170,000-220,000
SAR 3.................................  9,700-250,000              250,000                    86,000-114,000
SAR 4.................................  5,500-250,000              250,000                    150,000-240,000
SAR 5.................................  5-250,000                  GM=1217                               13-18

[[Page 34070]]

 
SAR 6.................................  160,000-250,000            250,000                    250,000
--------------------------------------------------------------------------------------------------------------------------------------------------------

List of Respirators

Powered Air-Purifying Respirators With Hoods/Helmets

(PAPR1) 3M Whitecap helmet with chinstrap with GVP blower (hard plastic 
helmet with bib).
(PAPR 2) 3M Snapcap hood with chinstrap with GVP-100 blower (Tyvek hood 
with bib).
(PAPR 3) Racal BE-5 (clear PVC hood with bib).
(PAPR 4) Racal BE-10 (Polycoated Tyvek hood with bib and head 
suspension).

Loose-Fitting Powered Air-Purifying Respirator

(PAPR 5) Racal BE-12 (Polycoated Tyvek loose-fitting facepiece).

Supplied-Air Respirators

(SAR 1) 3M Whitecap helmet with chinstrap (hard plastic helmet with 
bib).
(SAR 2) 3M Snapcap hood with chinstrap (Tyvek hood with bib).
(SAR 3) MSA VERSA-Hood with 5-613-1 direct hose connection for 
3/8'' hose system (Tyvek hood).
(SAR 4) North Model 85302 TB (Tyvek hood with ratchet head suspension 
and bib).
(SAR 5) North Model 85302 T (Tyvek hood with ratchet head suspension).
(SAR 6) Bullard CC2OTIC with 2ORT suspension and 2ONC chinstrap (Tyvek 
hood with bib).

    Note: All PAPRs tested with high-efficiency filters.

    The study report was finalized in 1999, and ORC requested that OSHA 
consider assigning an interim final APF of 1,000 to the study's high-
performing respirator models, with provisions for an APF as high as 
5,000 based on programmatic and environmental factors (Ex. 3-4-3, 1999 
communication with OSHA). ORC also recommended that, because the 
current NIOSH respirator certification procedures are not capable of 
distinguishing between high-performing PAPRs and SARs (and that some 
respirators may not provide adequate protection), the study methodology 
should be the basis for determining APFs for all respiratory protective 
equipment regulated by OSHA.
    In 2000, ORC renewed its requests. They pointed out that the study 
demonstrated that the PAPRs tested, including the loose-fitting 
facepiece PAPRs, were capable of achieving protection factors of 6,000 
to 10,000 (rather than the APF of 25 assigned by NIOSH and adopted by 
OSHA), and that the tested SARs achieved protection factors of 3,000 to 
10,000. However, one tested SAR model did not provide a protection 
factor of 25, demonstrating to the Agency the importance of testing 
specific equipment being considered for an increased APF to assure the 
expected protection.
    ORC asserted that new APFs for the models tested in the study were 
warranted. They believed that the study results justified a re-
evaluation of the methods for assessing the ability of PAPRs and SARs 
to provide protection against airborne particulates, and asked OSHA to 
issue a directive or similar document assigning an interim APF of 1,000 
for the SARs and PAPRs that tested successfully in the study. ORC 
believed that SWPF testing of PAPRs and SARs was beneficial, and 
strongly supported use of a collaborative approach as was pursued in 
developing the study.
    OSHA permitted use of an interim APF of 1,000 for 9 of the 11 
respirators tested and developed an enforcement policy similar to that 
followed for the Bullard, Clemco, and 3M respirators (Ex. 3-4-4; 2002 
memo to RAs). Again, the interim APFs are subject to a final APF 
determination resulting from this rulemaking. OSHA requests comments on 
all aspects of this study.
    LLNL/OSHA PAPR Study. OSHA requested that LLNL conduct two 
additional PAPR studies using the protocol of the 1995-96 ORC study. 
The raw data from the two evaluations were then compared with the ORC 
SWPF study data.
    A modified SWPF protocol was used to test two additional PAPRs, an 
MSA OptimAir and a Neoterik, selected by OSHA. The testing employed the 
same exercise protocol as the ORC study; however, only three test 
subjects participated in the evaluation. The three test subjects each 
performed four separate donnings of each respirator model. The 50th and 
95th percentiles of the penetration and protection factors for the two 
respirators are shown in Table 5.

                                                     Table 5
----------------------------------------------------------------------------------------------------------------
                                            Penetration                           Protection factor
       Respirator model        ---------------------------------------------------------------------------------
                                 50th percentile    95th percentile   50th percentile       95th percentile
----------------------------------------------------------------------------------------------------------------
MSA OptimAir..................  1.67 x 10-6(a)...  4.08 x 10-5.....  250,000(a)......  24,510
Neoterik......................  2.74 x 10-5......  1.43 x 10-3.....  36,563..........  698
----------------------------------------------------------------------------------------------------------------

    For the Neoterik, SWPFs of 100 and somewhat less were observed for 
the running in place and the moving bricks (building a concrete block 
wall) exercises. The Neoterik demonstrated SWPFs near 1,000 and 
somewhat less for the twisting head side to side, moving the head up 
and down, and touching toes exercises. For the MSA OptimAir, SWPFs 
approaching 100 for the running in place exercise were observed, while 
all of the other exercises resulted in SWPFs of 10,000 or greater. 
Penetration levels by type of exercise were compared between the OSHA 
PAPR analyses and the ORC results. In general, the comparison indicated 
that the same exercises triggered increased penetration values. That 
is, sources of penetration were ``running-in-place'' (for both 
respirators) and ``moving bricks'' (for the Neoterik PAPR).

V. Health Effects

    In a number of previous rulemakings, OSHA discussed the serious 
health effects caused by exposure to airborne chemical hazards (see, 
e.g., Appendix A of the Hazard Communication Standard

[[Page 34071]]

at 29 CFR 1910.1200, and the preambles to any of the Agency's 
substance-specific standards codified at 29 CFR 1910.1001 to 
1910.1052). When OSHA promulgates a new or revised PEL for a chemical 
air contaminant, (e.g., Arsenic, 29 CFR 1910.1018; Asbestos, 29 CFR 
1910.1001; Benzene, 29 CFR 1910.1028; Lead, 29 CFR 1910.1025; Ethylene 
Oxide, 29 CFR 1910.1047), it determines at what level of exposure to 
the contaminant employees develop serious health effects (e.g., 
exposure to the contaminant is life-threatening, causes permanent 
damage, or significantly impairs employees' ability to perform their 
jobs safely).
    As discussed in Section VI, ``Summary of the Final Economic 
Analysis,'' of the final Respiratory Protection Standard (63 FR 1171), 
OSHA estimated that improvements and clarifications made to the 
previous Respiratory Protection Standard would prevent, each year, 
between 843 and 9,282 (best estimate, 4,046) work-related injuries and 
illnesses, and between 351 and 1,626 (best estimate, 932) work-related 
deaths from cancer and chronic diseases such as cardiovascular disease. 
To support this estimate, OSHA used its Integrated Management 
Information System database to identify several substances that had a 
wide range of adverse effects, as well as documented workplace 
exposures that exceeded the PELs for these substances. The health 
effects associated with exposure to these substances include:
    [sbull] Sudden death or asphyxiation (e.g., from exposure to carbon 
monoxide, carbon dioxide);
    [sbull] Loss of lung function (e.g., from exposure to wood dust, 
welding fumes, manganese fumes, copper fumes, cobalt metal fumes, 
silica);
    [sbull] Central nervous system disturbances (e.g., from exposure to 
carbon monoxide, trichloroethylene);
    [sbull] Cancer (e.g., from exposure to chromic acid, wood dust, 
silica); and
    [sbull] Cardiovascular problems (e.g., from exposure to carbon 
monoxide).
    Furthermore, most of the airborne contaminants measured as part of 
the workplace protection factor studies considered during development 
of this proposal cause serious health effects. For example, acute lung, 
skin, and eye irritation occur as a result of occupational exposures to 
styrene, lead, strontium, benzo(a)pyrene, and silica. Longer-term 
exposures to other substances sampled in these studies cause bone and 
blood effects (lead particulates), neurological effects (mercury 
fumes), chronic lung damage (cotton dust), and cancer (asbestos fibers 
and chromium particulates).
    The risk that an employee will experience an adverse health outcome 
while exposed to a hazardous airborne substance is a function of the 
toxicity or hazardous characteristics of the substance, the 
concentrations of the substance in the air, the duration of exposure, 
the physiology of the employee, and workplace conditions. These factors 
combined assist in determination of the type of respirator selected to 
reduce an employee's exposure below the PEL for the hazardous 
substance. Under many workplace-exposure conditions, prevention of 
serious health effects depends substantially on the protection afforded 
to employees by a respirator.
    Employers need the APFs provided in this proposal to select 
appropriate respirators for employee use when engineering and work-
practice controls are insufficient to maintain hazardous substances at 
safe levels in the workplace. In this regard, the proposed APFs will 
permit employers to select respirators for employee protection based on 
the type of hazardous substance and the level of employee exposure to 
that substance, among other factors. OSHA strongly believes that proper 
respirator selection using the proposed APFs will protect employees 
from overexposure to hazardous substances, thus preventing the serious 
health effects that result from such overexposure.
    While APFs are an important factor in respirator selection, 
employers must consider other factors as well. In this regard, simply 
applying an APF to the level of an airborne contaminant in a workplace 
will not ensure that employees receive adequate protection. Throughout 
the preamble of the final Respiratory Protection Standard, OSHA 
demonstrated that adequate fit testing, proper respirator use, employee 
training, and thorough inspection and maintenance of respirators are 
some of the other factors essential to an effective respiratory 
protection program. The Agency believes that failure to comply with any 
of these program requirements substantially increases the chance that 
the respirator selected by the employer will not protect employees 
against hazardous air contaminants because of respirator malfunction, 
excessive leakage, improper use, or some combination of these problems. 
Therefore, employers should expect respirators to provide effective 
employee protection against the serious health effects of hazardous 
airborne substances only when they use the respirators in the context 
of a comprehensive respiratory protection program. If respirators are 
to provide employees with at least the minimum level of exposure 
protection listed in the proposed APF table, employers must comply with 
the other respiratory protection requirements specified under OSHA's 
Respiratory Protection Standard at 29 CFR 1910.134.
    In this rulemaking, OSHA also is proposing to supersede the 
existing APF requirements in its substance-specific standards. By 
superceding these requirements, the Agency expects that the benefits 
estimated for the proposed APFs under the Respiratory Protection 
Standard would be available to employers who must select respirators 
for employee use under the substance-specific standards. In addition, 
OSHA would be harmonizing the APF requirements in the substance-
specific standards with the APF requirements proposed for its 
Respiratory Protection Standard. The Agency believes that harmonization 
would reduce confusion among the regulated community and aid in uniform 
application of APFs, while maintaining employee protection at levels at 
least as protective as the existing APF requirements.

VI. Summary of the Preliminary Economic and Regulatory Flexibility 
Screening Analysis

A. Introduction

    OSHA's Preliminary Economic and Regulatory Flexibility Screening 
Analysis (PERFSA) addresses issues related to the costs, benefits, 
technological and economic feasibility, and economic impacts (including 
small business impacts) of the Agency's proposed Assigned Protection 
Factors (APF) rule. The Agency preliminarily determined that this rule 
is not an economically significant rule under Executive Order 12866. 
The economic analysis meets the requirements of both Executive Order 
12866 and the Regulatory Flexibility Act (RFA; as amended in 1996). The 
PERFSA presents OSHA's full economic analysis and methodology. The 
Agency entered the complete PERFSA into the docket as Exhibit 6-1. The 
remainder of this section summarizes the results of that analysis.
    The purpose of this PERFSA is to:
    [sbull] Identify the establishments and industries potentially 
affected by the rule;
    [sbull] Evaluate the costs employers would incur to meet the 
requirements of proposed APF rule;
    [sbull] Estimate the benefits of the rule;
    [sbull] Assess the economic feasibility of the rule for affected 
industries; and
    [sbull] Determine the impacts of the rule on small entities and the 
need for a Regulatory Flexibility Analysis.

[[Page 34072]]

B. The Rule and Affected Respirator Users

    OSHA's proposed APF rule would amend 29 CFR 1910.134(d)(3)(i)(A) of 
the Respiratory Protection Standard by specifying a set of APFs for 
each class of respirators. These APFs specify the highest multiple of a 
contaminant's permissible exposure limit (PEL) at which an employee can 
use a respirator safely. The proposed APFs would apply to respirator 
use for protection against overexposure to any substance regulated 
under 29 CFR 1910.1000. In addition, OSHA rules for specific substances 
under subpart Z (regulated under the authority of section 6(b)(5) of 
the OSH Act of 1970, 29 U.S.C. 655) specify APFs for respirators used 
for protection against these chemicals (hereafter referred to as 
section 6(b)(5) substances). The proposed rule would supercede most of 
these protection factors, and harmonize APFs for these substances with 
those for general respirator use.
    OSHA based estimates of the number of employees using respirators 
and the corresponding number of respirator-using establishments on the 
recent NIOSH-BLS survey of respirator use and practices \1\ (Ex. 6-3). 
The NIOSH-BLS survey provides up-to-date use estimates by two-digit 
industry sector and respirator type for establishments in which 
employees used respirators during the previous 12 months.\2\ As shown 
in Table VI-1, an estimated 291,085 establishments reported respirator 
use in industries covered by OSHA's proposed regulation. Most of these 
establishments (208,528 or 71.6 percent) reported use of filtering 
facepieces. Substantial percentages of establishments also reported the 
use of half-mask and full facepiece nonpowered air-purifying 
respirators (49.0 and 21.4 percent, respectively). A smaller number of 
establishments reported use of powered air-purifying respirators 
(PAPRs) and supplied-air respirators (SARs). Fifteen percent of 
establishments with respirators (43,154) reported using PAPRs and 19 
percent (56,022) reported using SARs. Table VI-2 presents estimates of 
the number of respirator users by two-digit industry sector. An 
estimated 2.3 million employees used filtering facepiece respirators in 
the last 12 months, while 1.5 million used half masks, and 0.7 million 
used full facepiece nonpowered air-purifying respirators. Fewer 
employees reported using PAPRs (0.3 million) and SARs (0.4 million). 
The industry-specific estimates show substantial respirator use in 
several industries, including the construction sector, several 
manufacturing industries (SICs 28, 33, 34, and 37), and Health services 
(SIC 80).
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    \1\ Preliminary results from the 2001 NIOSH-BLS ``Survey of 
Respirator Use and Practices'', in press. NIOSH commissioned the 
survey to be conducted by BLS, who also tabulated the data after 
completing the survey.
    \2\ The survey was conducted between August 2001 and January 
2002. It asked: ``During the past 12 months, how many of your 
current employees used respirators at your establishment?'' It 
excluded voluntary use of respirators from detailed followup 
respirator use questions (Ex. 6-3).
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    The proposed standard would have different impacts on employers 
using respirators to comply with OSHA substance-specific standards than 
for employers using respirators for other purposes. Therefore, OSHA 
used findings from the NIOSH-BLS survey of establishments that reported 
respirator use, by general respirator class, for protection against 
specific substances (see Table VI-3). OSHA applied these numbers to all 
respirator users and establishments within the industries that make up 
each sector to derive substance-specific estimates of respirator use. 
For those section 6(b)(5) substances not reported by NIOSH, OSHA used 
expert judgments of a consultant with experience in the respirator 
industry to estimate the percentage of establishments and employees 
that use respirators for protection against these chemicals (Ex. 6-2) 
(see Table VI-3).

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C. Compliance Costs

    The proposal does not raise issues of technological feasibility 
because it requires only that employers use respirators already on the 
market. However, costs of the proposed APFs result from requiring some 
users to switch to more protective respirators than they currently use. 
When the proposed APF is lower than the baseline (current) APF, 
respirator users must upgrade to a more protective model. Both the 1992 
ANSI Z88.2 Respiratory Protection Standard and the 1987 NIOSH RDL 
specify APFs for certain classes of respirators. The Agency assumed 
that employers currently use the ANSI or NIOSH APFs, or the APFs in the 
OSHA substance-specific standards, as applicable, to select 
respirators. While the Agency currently refers to the NIOSH RDL as its 
primary reference for APFs, in the absence of an applicable OSHA 
standard, this analysis assumes that, in most cases, adhering to the 
existing ANSI APFs fulfills employers' legal obligation for proper 
respirator selection under the existing Respiratory Protection 
Standard. However, in the case of full facepiece negative pressure 
respirators, the Agency has established that an APF of 50, as opposed 
to ANSI's APF of 100, is currently acceptable. In this regard, all but 
one of the substance-specific standards with APFs for full facepiece 
negative pressure respirators set an APF of 50. In addition, the 
existing respirator rule and its supporting preamble require that 
quantitative fit testing of full facepiece negative pressure 
respirators must achieve a fit factor of 500 when employees use them in 
atmospheres in excess of 10 times the PEL; this requirement assumes a 
safety factor of 10. Therefore, based on a fit factor of 500, such 
respirators would be safe to wear in atmospheres up to 50 times the 
PEL, consistent with similar requirements regarding respirator use 
found in existing standards for section 6(b)(5) chemicals.
    For each respirator type, OSHA compared the proposed and current 
APF requirements, including existing APFs for section 6(b)(5) 
substances, and identified an incrementally more protective respirator 
model. To be adequate, the more protective respirator must have a 
proposed APF greater than the current APF.
1. Number of Users Required To Upgrade Respirator Models
    For a given respirator type, the number of users required to shift 
to a more protective respirator depends on two factors: The total 
number of users of that type, and the percentage of those users for 
whom the ambient exposure level is greater than the proposed APF. While 
survey data are available to estimate the number of users, virtually no 
information is available in the literature that provides a basis for 
estimating the percentage of users required to upgrade respirators. The 
percentage of workers switching respirators would depend on the profile 
or frequency distribution of users' exposure to contaminants relative 
to the PEL. For example, the Agency proposed to lower the APF for full 
facepiece respirators used to protect against cotton dust from 100 to 
50; accordingly, when workers have ambient exposures that are greater 
than 50 times the PEL, employers must upgrade the respirator from a 
full facepiece negative pressure respirator to a more protective 
respirator (e.g., a PAPR).
    Because of the absence of data on this issue, OSHA made several 
assumptions regarding the requirement to upgrade respirators. First, 
OSHA assumed that employers use respirators only when their employees 
have exposures above the PEL. Second, OSHA assumed employers use the 
most inexpensive respirator permitted. These assumptions most likely 
overestimate the cost of compliance because many employers require 
their employees to use respirators when OSHA does not require such use, 
or they require respirators with higher APFs than OSHA currently 
requires. As a result, this analysis assumes shifts in respirators that 
employers may have implemented already.
    The Agency estimated distributions of exposures above the PELs 
based on reports from its Integrated Management Information System 
describing workplace monitoring of section 6(b)(5) toxic substances 
performed during OSHA health inspections. Of the 9,095 samples reported 
above the PELs, 68.0 percent reported exposures between 1 and 5 times 
the PEL, 13.1 percent found exposures between 5 and 10 times the PEL, 
and 9.5 percent documented exposures between 10 and 25 times the PEL. 
Exposures for the remaining 9.4 percent of the samples were greater 
than 25 times the PEL. Based on these data, OSHA modeled the current 
exposure distribution for each respirator type.
2. Incremental Costs of Upgrading Respirator Models
    OSHA also analyzed the costs of upgrading from the current 
respirator to a more protective alternative. In doing so, OSHA 
estimated the annualized unit costs for each respirator type, including 
equipment and accessory costs, and the costs for training and fit 
testing. OSHA then calculated the incremental cost for each combination 
of upgrades from an existing model to a more protective one, taking 
into account the effect of replacement before the end of the 
respirator's useful life. These annualized costs range from $49.98 (for 
upgrading from a supplied-air, demand mode, full facepiece respirator 
to a supplied-air, continuous flow, half-mask respirator) to $963.73 
(for upgrading from a nonpowered, air-purifying full facepiece 
respirator to a full facepiece PAPR).
    In certain instances, workers who use respirators under the 
substance-specific standards may have to upgrade to a SAR with an 
auxiliary escape SCBA. Several substance-specific standards currently 
specify SARs for exposures that exceed 1,000, times the PEL.\3\ OSHA 
believes that workers are unlikely to regularly use respirators at such 
extreme exposure levels, i.e., they are most likely to use them only in 
exceptional, possibly emergency-related situations. Furthermore, 
exposures at levels more than 1,000 times the PEL would generally be at 
or above levels deemed immediately dangerous to life or health (IDLH), 
so employers already are required by the Respiratory Protection 
Standard to provide each worker with a respirator that has SCBA 
capability. For these reasons, this PERFSA estimated no impacts for 
these situations.\4\
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    \3\ These standards regulate cotton dust, coke oven emissions, 
acrylonitrile, arsenic, DBCP, ethylene oxide, and lead.
    \4\ Paragraph (d)(2) of the Respiratory Protection Standard 
requires employers to provide either a pressure demand SCBA or a 
pressure demand SAR with auxiliary SCBA to any employee who works in 
IDLH atmospheres.
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3. Aggregate Compliance Costs
    For each respirator type affected by the proposed regulation, OSHA 
combined the incremental costs of upgrading to a more protective 
respirator, the estimated share of users forecast to upgrade, and the 
number of users involved to estimate the compliance costs associated 
with each respirator type. Table VI-4 shows estimated compliance costs 
for OSHA's proposed APF rule of $4.6 million. The proposed rule would 
require 1,918 users of nonpowered air-purifying respirators to upgrade 
to some respirator more expensive than they are now using at a cost of 
$1.8 million. The Agency estimates that 22,848 PAPR users would upgrade 
their respirators at a cost of $2.3 million. A relatively small number 
of SAR users (5,110) would upgrade to more expensive respirators at a 
cost of

[[Page 34080]]

$0.4 million. Industry-specific compliance costs vary according to the 
number of respirator users and the proportion of these users affected 
by the proposed rule. Industries with relatively large compliance costs 
include SIC 17, Special trade contractors ($0.8 million), and SIC 80, 
Health services ($0.8 million). Potentially offsetting these costs are 
a limited number of cases where employers would be allowed to shift to 
a less expensive respirator.
    As discussed previously, however, the Agency believes the actual 
costs of the proposal almost certainly are overestimated. The cost 
analysis assumes all respirator wearers have levels of exposures that 
require the particular respirator they are using. Under this 
assumption, OSHA estimates over 15,000 employees would be allowed to 
safely shift to a less expensive respirator, which could lead to cost 
savings for the employer. Such potential cost savings are not accounted 
for in this cost analysis.
    In many cases, however, employers use respirators when respirators 
are not required by OSHA, or use respirators more protective than 
required by OSHA. As a result, OSHA's cost analysis overestimates the 
number of employees who are affected by the standard, and therefore 
overestimates costs associated with the standard.
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D. Benefits

    The benefits that would accrue to respirator users and their 
employers take several forms. The proposed standard would benefit 
workers by reducing their exposures to respiratory hazards. Improved 
respirator selection would augment previous improvements to the 
Respiratory Protection Standard, such as better fit-test procedures and 
improved training, contributing substantially to greater worker 
protection. Estimates of benefits are difficult to calculate because of 
uncertainties regarding the existing state of employer respirator-
selection practices and the number of covered work-related illnesses. 
At the time of the 1998 revisions to the Respiratory Protection 
Standard, the Agency estimated that the standard would avert between 
843 and 9,282 work-related injuries and illnesses annually, with a best 
estimate (expected value) of 4,046 averted illnesses and injuries 
annually (63 FR 1173). In addition, OSHA estimated that the standard 
would prevent between 351 and 1,626 deaths annually from cancer and 
many other chronic diseases, including cardiovascular disease, with a 
best estimate (expected value) of 932 averted deaths from these causes. 
The APFs proposed in this rulemaking help ensure these benefits are 
achieved, as well as provide an additional degree of protection. The 
proposed APFs would reduce employee exposures to several section 
6(b)(5) chemicals covered by standards with outdated APF criteria, 
thereby reducing exposures to chemicals such as asbestos, lead, cotton 
dust, and arsenic.\5\ While the Agency did not quantify these benefits, 
it estimates that 29,655 employees would have a higher degree of 
respiratory protection under the proposed APF standard. Of these 
employees, an estimated 8,384 have exposure to lead, 7,287 to asbestos, 
and 3,747 to cotton dust, all substances with substantial health risks.
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    \5\ In the 1998 rulemaking revising the Respiratory Protection 
Standard, the Final Economic Analysis noted that the standard would 
not directly affect the benefits for the estimated 5% of employees 
who use respirators under OSHA's substance-specific health standards 
(except to the extent that uniformity of provisions improve 
compliance). Therefore, the Agency likely over-estimated the 
benefits of that rulemaking since the standard did not affect 
directly the type of respirator used by those employees (63 FR 
1173). Conversely, this proposed rulemaking directly addresses the 
APF provisions of the substance-specific standards; therefore, this 
proposal would affect directly the respirators used by employees 
covered by these standards.
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    In addition to health benefits, OSHA believes other benefits would 
result from the harmonization of APF specifications, thereby making 
compliance with the respirator rule easier for employers. Employers 
also would benefit from greater administrative ease in proper 
respirator selection. Employers would no longer have to consult several 
sources and several OSHA standards to determine the best choice of 
respirator, but could make their choices based on a single, easily 
found regulation. Some employers who now hire consultants to aid in 
choosing the proper respirator should be able to make this choice on 
their own with the aid of the proposed rule. In addition to having only 
one set of numbers (i.e., APFs) to assist them with respirator 
selection for nearly all substances, some employers may be able to 
streamline their respirator stock by using one respirator class to meet 
their respirator needs instead of several respirator classes. The 
increased ease of compliance would also yield additional health 
benefits to employees using respirators.
    The proposed APFs would clarify when employers can safely place 
employees in respirators that impose less stress on the cardiovascular 
system (e.g., filtering facepiece respirators). Many of these 
alternative respirators may have the additional benefit of being less 
expensive to purchase and operate. As previously discussed, OSHA 
estimates that over 15,000 employees currently use respirators that 
would fall in this group (i.e., shift to a less expensive respirator).

E. Economic Feasibility

    OSHA is required to set standards that are feasible. To demonstrate 
that a standard is feasible, the courts have held that OSHA must 
``construct a reasonable estimate of compliance costs and demonstrate a 
reasonable likelihood that these costs will not threaten the existence 
or competitive structure of an industry'' (United Steelworkers of 
America, AFL-CIO-CLC v. Marshall (the ``Lead'' decision), 647 F2d 1189 
(DC Cir. 1980)).
    OSHA conducted its analysis of economic feasibility on an 
establishment basis. Accordingly, for each affected industry, the 
Agency compared estimates of per-establishment annualized compliance 
costs with per-establishment estimates of revenues and per-
establishment estimates of profits. It used two worst-case assumptions 
regarding the ability of employers to pass the costs of compliance 
through to their customers: The no-cost-pass-through assumption, and 
the full-cost-pass-through assumption. Based on the results of these 
comparisons, which define the universe of potential impacts of the 
proposed APFs, OSHA then assessed the proposal's economic feasibility 
for all affected establishments, i.e., those covered by the proposal.
    The Agency assumed that establishments falling within the scope of 
the proposal would have the same average sales and profits as other 
establishments in their industries. OSHA believes this assumption is 
reasonable because no evidence is available showing that the financial 
characteristics of those firms with employees who use respirators are 
different from firms that do not use respirators. Absent such evidence, 
OSHA relied on the best available financial data (those from the Bureau 
of the Census (Ex. 6-4) and Robert Morris Associates (Ex. 6-5)), used a 
commonly accepted methodology to calculate industry averages, and based 
its analysis of the significance of the projected economic impacts and 
the feasibility of compliance on these data.
    The analysis of the potential impacts of the proposed APF standard 
on before-tax profits and sales shown in Table VI-5 is a ``screening 
analysis,'' so called because it simply measures costs as a percentage 
of pre-tax profits and sales under the worst-case assumptions discussed 
above, but does not predict impacts on these before-tax profits or 
sales. OSHA used the screening analysis to determine whether the 
compliance costs potentially associated with the proposed standard 
could lead to significant impacts on all affected establishments. The 
actual impact of the proposal on the profit and sales of establishments 
in a specific industry would depend on the price elasticity of demand 
for the products or services of these establishments.

[[Page 34084]]

    Table VI-5 shows the economic impacts of these costs. For each 
industry, OSHA constructed the average compliance cost per affected 
establishment and compared it to average revenues and average 
profits.\6\ These costs are quite small, i.e., less than 0.005 percent 
of revenues; the one major exception is SIC 44 (Water transportation), 
for which OSHA estimated the costs impacts to be 0.16 percent of 
revenues. When the Agency compared average compliance costs with 
profits, the costs also are small, i.e., less than 0.17 percent; again, 
the major exception was SIC 44, which had an estimated impact of 2.12 
percent of profits.\7\ Based on the data for establishments in all 
industries shown in Table VI-5, OSHA concludes that the APF proposal is 
economically feasible for the affected establishments.
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    \6\ OSHA defines ``affected establishment'' as any facility that 
uses respirators, as represented in the NIOSH-BLS survey data.
    \7\ For some industries, such as SIC 44, data from the NIOSH-BLS 
survey were suppressed due to low response rates. In these cases, 
the Agency, for the purposes of assessing economic feasibility, 
imputed broader sector-level data from the survey to form an 
estimate of respirator use. This procedure may result in 
overestimating the impact of the proposal in some industries. See 
the full PEA (Ex. 6-1) for further details.
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F. Economic Impacts to Small Entities

    OSHA also estimated the economic impacts of the proposed rule on 
affected entities with fewer than 20 employees, and for affected small 
entities as defined by the Small Business Administration (SBA). Table 
VI-6 shows the estimated economic impacts for small entities with fewer 
than 20 employees: Average compliance costs by industry are less than 
0.005 percent of average revenues, and less than 0.19 percent of 
profits, in all industries. Table VI-7 presents the economic impacts 
for small entities as a whole, as defined by SBA. For these firms, 
average compliance costs are less than 0.005 percent of average 
revenues and less than 0.03 percent of average profits. Thus, the 
Agency projects no significant impacts from the proposed rule on small 
entities.
    When costs exceed one percent of revenues or five percent of 
profits, OSHA considers the impact on small entities significant for 
the purposes of complying with the RFA. For all classes of affected 
small entities, the Agency found that the costs were less than one 
percent of revenues and five percent of profits. Therefore, OSHA 
certifies that this proposed regulation would not have a significant 
impact on a substantial number of small entities.

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VII. Summary and Explanation of the Proposed Standard

    This section of the preamble provides a summary and explanation of 
each proposed revision to OSHA's Respiratory Protection Standard 
involving assigned protection factors.

A. Revisions to the Respiratory Protection Standard

    This section addresses the revisions proposed for paragraphs (b), 
(d)(3)(i)(A), (d)(3)(i)(B), and (n) of OSHA's exiting Respiratory 
Protection Standard at 29 CFR 1910.134).
Paragraph (b)--Definitions
    Revisions to this paragraph would add two important definitions''--
assigned protection factor'' and ``maximum use concentration''--to 
OSHA's Respiratory Protection Standard. The following sections explain 
these proposed definitions in detail.
1. Assigned Protection Factor
    As part of its 1994 proposed rulemaking for the Respiratory 
Protection Standard, OSHA proposed a definition for assigned protection 
factors (APFs) that read as follows: ``[T]he number assigned by NIOSH 
[the National Institute for Occupational Safety and Health] to indicate 
the capability of a respirator to afford a certain degree of protection 
in terms of fit and filter/cartridge penetration'' (59 FR 58938). OSHA 
proposed this definition on the assumption that NIOSH would develop 
APFs for the various respirator classes, building on the APFs in the 
1987 NIOSH Respirator Decision Logic (RDL) (59 FR 58901-58903). 
However, NIOSH subsequently decided not to publish a list of APFs as 
part of its 42 CFR part 84 Respirator Certification Standards (60 FR 
30338), and reserved APFs for a future NIOSH rulemaking.
    During his opening statement on June 15, 1995 at an OSHA-sponsored 
expert-panel discussion on APFs, Dr. Adam Finkel, then Director of the 
Agency's Directorate of Health Standards Programs, noted that OSHA 
would explore developing its own list of APFs (H-049, Ex. 707-X). The 
Agency then announced in the preamble to the final Respiratory 
Protection Standard (63 FR 1182) that it would propose an APF table 
``based on a thorough review and analysis of all relevant evidence'' in 
a subsequent rulemaking. In the final Respiratory Protection Standard, 
OSHA reserved a table for APFs, a paragraph [(d)(3)(i)(A)] for APF 
requirements, and a definition of APF under paragraph (b).
    In its 1987 RDL, NIOSH defined APF as ``[t]he minimum anticipated 
protection provided by a properly functioning respirator or class of 
respirators to a given percentage of properly fitted and trained 
users'' (Ex. 1-54-437Q). The American National Standards Institute 
(ANSI) developed a definition for APF in its Z88.2-1992 Respiratory 
Protection Standard that reads, ``The expected workplace level of 
respiratory protection that would be provided by a properly functioning 
respirator or class of respirators to properly fitted and trained 
users' (Ex. 1-50). The ANSI Z88.2 Subcommittee that developed the 1992 
standard used the NIOSH definition of APF as a template for its APF 
definition; however, the Z88.2 Subcommittee revised the phrase 
``minimum anticipated protection'' in the NIOSH definition to 
``expected workplace level of respiratory protection.'' It also dropped 
the NIOSH phrase ``to a given percentage'' from its definition.
    The phrase ``a given percentage'' implies that some respirator 
users will not achieve the full APF under workplace conditions. The 
``given percentage'' usually is about five percent, which is a 
percentage derived from statistical analyses of workplace protection 
factor (WPF) studies. In this regard, five percent represents the fifth 
percentile of the geometric distribution of protection factors for 
individual participants in a WPF study. Each participant's protection 
factor is the concentration of challenge agent outside the respirator 
(Co) divided by the concentration of that agent inside the 
participant's respirator (Ci), or Co/
Ci); therefore, the fifth percentile is the threshold for 
specifying the APF for the respirator tested under those workplace 
conditions. Using the fifth percentile means that about five percent of 
the employees who use the respirator under these workplace conditions 
may not achieve the level of protection assigned to the respirator (or 
class of respirators). Most WPF studies adopt the fifth-percentile 
threshold as the conventional standard, recognizing that about five 
percent of respirator users will not attain the APF determined for the 
respirator or class of respirators even when they receive proper fit 
testing and use the respirator correctly as part of a comprehensive 
respiratory protection program. However, ANSI dropped the phrase ``to a 
given percentage'' to reduce confusion (i.e., the phrase did not 
specify a percentage), and to emphasize the level of protection needed 
by the vast majority of employees who use respirators in the workplace.
    The Agency's review of the available data on respirator 
performance, as well as findings from the personal protective equipment 
surveys (Exs. 6-1, 6-2), indicate that the existing definitions of APF 
are confusing to the respirator-using public. Accordingly, OSHA 
believes that the proposed definition would reduce confusion among 
employers and employees regarding APFs, thereby assisting employers in 
providing their employees with effective respirator protection 
consistent with its Respiratory Protection Standard.
    The Agency revised the terms in the ANSI APF definition to improve 
clarity. OSHA's proposed definition for APF reads as follows:

    Assigned protection factor (APF) means the workplace level of 
respiratory protection that a respirator or class of respirators is 
expected to provide to employees when the employer implements a 
continuing, effective respiratory protection program as specified by 
29 CFR 1910.134.

    The revisions made to the ANSI APF definition in developing this 
proposed APF definition include adding the phrase ``when the employer 
implements a continuing, effective respiratory protection program as 
specified by 29 CFR 1910.134.'' The Agency added this phrase to 
emphasize the requirement that employers must select a respirator in 
the context of a comprehensive respiratory protection program. 
Accordingly, the APFs in Table I of this proposal do not apply when any 
of the program elements required by OSHA's Respiratory Protection 
Standard are absent from an employer's respirator program, including 
fit testing, maintenance, selection, use, training, and other specified 
elements. This wording is necessary because the level of employee 
protection afforded by the proposed APFs depends on the other elements 
of a comprehensive respiratory protection program being in place 
continuously, and operating effectively. Employers and employees cannot 
expect to achieve an APF reliably unless employers ensure that their 
employees use respirators in accordance with a continuing, effective 
respiratory protection program.
    The proposed APF definition is an important addition to the 
Respiratory Protection Standard because it informs employers how the 
APF constrains respirator use. The APF can only be achieved by a 
respirator or class of respirators that are functioning properly in 
accordance with paragraphs (b) and (j) of the Respiratory Protection 
Standard. This means that the respirator must be capable of performing 
its

[[Page 34093]]

function of reducing employee exposures to airborne contaminants by 
being in correct working order. Accordingly, employers must maintain 
the respirator properly, with no defects such as cracked or distorted 
facepiece seals, missing exhalation valves, broken straps, or any other 
defect that would cause leakage into the respirator or prevent proper 
operation. For air-purifying respirators, the filters must be 
appropriate for the airborne contaminant, and provide an adequate 
service life.
    Employers must properly fit and train employees for respirator use, 
which addresses the requirements in paragraphs (f) and (k) of the 
Respiratory Protection Standard. Therefore, employers must fit 
employees with the size and model of respirator they will be using in 
the workplace. They must then wear that same size and model of 
respirator in the workplace, and follow the training they receive for 
performing respirator seal checks, inspections for correct respirator 
operation, and proper donning and wearing the respirator.
2. Maximum Use Concentration
    Employers use MUCs to select appropriate respirators, especially 
for use against organic vapors and gases since the MUC specifies the 
maximum atmospheric concentration of a hazardous substance against 
which a specific respirator or class of respirators with a known APF 
can protect employees who use these respirators. MUCs are a function of 
the assigned protection factor (APF) determined for a respirator (or 
class of respirators) and the exposure limit of the hazardous 
substance.
    Ed Hyatt in the 1976 LASL report on Respiratory Protection Factors 
(Ex. 2) recounted the early history of maximum use concentration (MUC), 
starting with the MUC recommendations of the joint American Industrial 
Hygiene Association and American Conference of Governmental Industrial 
Hygienists committee in 1961. This committee recommended that, for 
highly toxic compounds, full facepiece respirators with high-efficiency 
filters should use a maximum limit of 100 x the threshold limit value 
(TLV). In 1961, in the United Kingdom, Hyatt noted that Letts 
recommended that half-mask dust respirators provided effective 
protection against airborne contaminants no greater than 10 x the TLV.
    In 1974, NIOSH and OSHA started the Standards Completion Program to 
develop standards for substances with existing permissible exposure 
limits (PELs). This process resulted in the development of NIOSH 
Criteria Documents, each of which provided technical information and 
recommendations for specific airborne contaminants. These documents 
also recommended MUCs for different types of respirators; NIOSH 
obtained the information for these MUCs from various sources, including 
NIOSH Current Intelligence Bulletins and recognized industrial hygiene 
references. NIOSH later published this information in its Pocket Guide 
to Chemical Hazards. Other source documents for MUC definitions and 
regulations include the 1987 NIOSH RDL, and the ANSI Z88.2-1980 and 
ANSI Z88.2-1992 respiratory protection standards.
    OSHA's 1994 proposed Respiratory Protection Standard contained the 
following definition for MUC:

    Maximum use concentration (MUC) means the maximum concentration 
of an air contaminant in which a particular respirator can be used, 
based on the respirator's assigned protection factor. The MUC cannot 
exceed the use limitations specified on the NIOSH approval label for 
the cartridge, canister, or filter. The MUC can be determined by 
multiplying the assigned protection factor for the respirator by the 
permissible exposure limit for the air contaminant for which the 
respirator will be used.

    Several commenters to the 1994 proposal recommended alternatives to 
this definition. Reynolds Metal Company recommended defining MUC as 
``the maximum concentration of an air contaminant in which a particular 
respirator can be used, based on the respirator's assigned protection 
factor'' (Ex. 1-54-222). The American Petroleum Institute (API) noted 
NIOSH developed the term ``MUC,'' and that, to avoid confusion, OSHA 
should not use the term (Ex. 1-54-330). API proposed using the term 
``assigned use concentration'' to replace ``MUC''; API defined 
``assigned use concentration'' as ``the maximum concentration of an air 
contaminant in which a particular respirator can be used, based on the 
respirator's assigned protection factor'' (Ex. 1-54-330). However, when 
the Agency published the final Respiratory Protection Standard in 1998, 
it reserved the definition of MUC in paragraph (b) and MUC requirements 
in paragraph (d)(3)(i)(B) for future rulemaking.
    Employers use MUCs to select appropriate respirators, especially 
for use against organic vapors and gases. In this regard, the MUC 
specifies the maximum concentration of a toxic vapor or gas at which a 
respirator will provide protection to an employee who uses the 
respirator. Accordingly, in this proposed rulemaking, OSHA defines MUC 
as follows:

    Maximum use concentration (MUC) means the maximum atmospheric 
concentration of a hazardous substance from which an employee can be 
expected to be protected when wearing a respirator, and is 
determined by the assigned protection factor of the respirator or 
class of respirators and the exposure limit of the hazardous 
substance. The MUC usually can be determined mathematically by 
multiplying the assigned protection factor specified for a 
respirator by the permissible exposure limit, short-term exposure 
limit, ceiling limit, peak limit, or any other exposure limit used 
for the hazardous substance.

    Under this proposed definition, MUC represents the maximum 
atmospheric concentration of a hazardous substance against which a 
specific respirator or class of respirators with a known APF can 
protect employees who use these respirators. Accordingly, MUCs are a 
function of the assigned protection factor (APF) determined for a 
respirator (or class of respirators) and the exposure limit of the 
hazardous substance.
    The last sentence in the proposed definition describes this 
function in terms of a mathematical calculation, i.e., that employers 
can ``usually'' determine the MUC by multiplying the APF for the 
respirator by the exposure limit used for the hazardous substance.\8\ 
The term ``usually'' in this sentence is consistent with paragraph 
(d)(3)(i)(B)(2), which is part of the proposed MUC requirements (see 
section below titled ``Regulatory Text for Maximum Use 
Concentrations.'') This proposed paragraph reads, ``Employers must 
comply with the respirator manufacturer's MUC for a hazardous substance 
when the manufacturer's MUC is lower than the calculated MUC specified 
by this standard.'' Therefore, while employers would use the proposed 
calculation to determine most MUCs, they would have to use MUCs 
determined by respirator manufacturers when these MUCs are lower than 
the MUCs determined using the proposed calculation. As noted below in 
the explanation of proposed paragraph (d)(3)(i)(B)(2), OSHA believes 
that this requirement would provide employees with a necessary added 
measure of protection from hazardous substances in the workplace.
---------------------------------------------------------------------------

    \8\ For example, when the hazardous substance is nitrobenzene 
(with a PEL of 1 ppm), and the respirator used by employees has an 
APF of 10, then the calculated MUC is 10 ppm (i.e., 1ppm x 10).
---------------------------------------------------------------------------

    Importantly, the last part of the proposed definition specifies 
exposure limits as ``permissible exposure limit (PEL), short-term 
exposure limit (STEL),

[[Page 34094]]

ceiling limit (CL), peak limit, or any other exposure limit used for 
the hazardous substance.'' The exposure limits are consistent with the 
terms used in the Z tables in 29 CFR 1910.1000 and the substance-
specific standards in 29 CFR parts 1910, 1915, and 1926.
    The phrase ``any other exposure limit used for the hazardous 
substance'' refers to exposure limits other than the exposure limits 
specified in the OSHA Z tables or in its substance-specific standards; 
employers use the other exposure limits to provide additional 
protection to employees or to comply with OSHA's general-duty clause 
(Section 5(a)(1) of the OSH Act; 29 U.S.C. 654 where OSHA has no 
standard). Employers may adopt such exposure limits from existing 
consensus standards (e.g., the ACGIH TLVs), or develop them 
specifically for the unique hazardous substances found in their 
workplaces.
Paragraph (d)(3)(i)(A)--APF Provisions
1. Introduction
    As early as 1976, respirator scientists were classifying 
respirators into distinct groups based on the level of protection they 
provided. These early respirator classes are similar to the classes now 
in use, as well as the classes developed by OSHA for this proposal. In 
the following parts of this section, the Agency describes the 
historical development of APFs for specific classes of respirators, and 
then explains OSHA's proposed APF for each of these respirator classes.
    In addition to basing the APFs proposed in this rulemaking on the 
studies and previous APF standards described in this section, the 
Agency contracted with Dr. Kenneth Brown to conduct statistical 
analyses of the original data reported in most of the WPF studies 
reported below. Dr. Brown's quantitative analyses justify combining 
data for filtering facepiece and elastomeric half-mask respirators in 
determining an APF for these two respirator classes, and using a 
qualitative analysis of the data for identifying APFs separately for 
powered air-purifying respirators, supplied-air respirators, and self-
contained breathing apparatuses. (Note that insufficient WPF data were 
available for Brown to include full facepiece air-purifying respirators 
in his analyses.) OSHA discusses the procedures and results of these 
statistical analyses in section IV of this preamble. The Agency 
believes that the APFs developed through the procedures discussed below 
are consistent with the results of the analyses performed by Dr. Brown.
2. Half-Mask Air-Purifying Respirators
    Historical development of APFs for half-mask air-purifying 
respirators. In 1976, Ed Hyatt of LANL tested eight commercially 
available Bureau of Mines (the Federal agency then designated to 
approve respirators) half-mask respirators (Ex. 2). Based on 
quantitative fit testing results obtained from a respirator test 
panel,\9\ Hyatt assigned six of these respirators an APF of 10; the 
remaining two respirators performed less effectively than the other 
six, thereby achieving an APF of less than 10. Hyatt did not use data 
from the two poor performing respirators to set the APF of 10 for the 
class because, as he stated in his report, ``For practical purposes, 
the remaining two models are not available.''
---------------------------------------------------------------------------

    \9\ LANL developed a respirator test panel consisting of 25 men 
and women selected to have face sizes representing about 95% of the 
U.S. working population (Ex. 7, docket H049).
---------------------------------------------------------------------------

    In 1980, the ANSI Z88.2 Respiratory Protection Standard (i.e., 
``the 1980 ANSI standard;'' Ex. 10, Docket H049) required fit testing 
to identify grossly misfitting half-mask respirators. That standard 
assigned an APF of 10 to half-mask air-purifying respirators when 
employers performed qualitative fit testing, and an APF as high as 100 
when they performed quantitative fit testing (Ex. 10, Table 5, p. 21, 
Docket H049). ANSI based the latter APF on the results of studies that 
quantitatively fit tested a panel of respirator users, much as Hyatt 
did in 1976 (Ex. 2).
    NIOSH developed its RDL in 1987 (Ex. 1-54-437Q), which assigned an 
APF of 5 to single-use and quarter mask air-purifying respirators, and 
an APF of 10 to half-mask respirators, including disposable half-mask 
respirators. In developing these APFs, NIOSH used results from 
quantitative fit-test studies performed on its own respirator test 
panel, several LANL quantitative fit-test studies (including Hyatt's 
1976 study), and several WPF studies that it conducted in the early 
1980s (Exs. 1-64-42, 1-64-47).
    The 1992 Z88.2 ANSI Respiratory Protection Standard (i.e., ``the 
1992 ANSI standard''; Ex. 1-50) retained an APF of 10 for half-mask 
air-purifying respirators, including quarter masks, disposable half-
masks, and half-masks with elastomeric facepieces. In determining these 
APFs, a committee of respirator experts convened by ANSI reviewed and 
discussed available APF studies, and then arrived at a final decision 
using a consensus process.
    The following table summarizes the previous APFs assigned to half-
mask air-purifying respirators, beginning with Hyatt's studies at LLNL 
in 1976 through the 1992 ANSI standard.

----------------------------------------------------------------------------------------------------------------
                                                                        APFs
      Half-mask air-purifying      -----------------------------------------------------------------------------
            respirators                                                                              1992 ANSI
                                      LANL (1976)     1980 ANSI standard      NIOSH RDL (1987)       standard
----------------------------------------------------------------------------------------------------------------
Single use (no longer available)                 5  .....................  5....................  ..............
 \1\.
Filtering facepiece...............  ..............  .....................  10 (disposable)......              10
Half-mask (elastomeric)...........              10  10 (with QLFT) 100     10...................             10
                                                     max. (with QNFT).
----------------------------------------------------------------------------------------------------------------
\1\ Filtering facepieces replaced single-use respirators.

    OSHA's proposed APFs for half-mask air-purifying respirators. 
Respirator manufacturers construct elastomeric half-masks using 
malleable compounds (e.g., silicon, natural or synthetic rubber) that 
readily conform to the respirator user's face, thereby effectively 
sealing the inside of the mask against penetration by airborne 
hazardous substances. Filtering facepieces also are available in a 
variety of designs and materials that affect their fit to a user's 
face. For example, the design of the ``fold flat'' filtering facepiece 
allows employees to fold them for easy carrying and storage; when 
employees need this respirator for protection, they unfold the mask and 
place the fabric filter over their mouth and nose and then position the 
attached elastic headbands or straps around their head.
    Half-mask respirators, including the subclasses of elastomeric and 
filtering facepiece respirators, vary widely in

[[Page 34095]]

design and construction; these characteristics could result in 
different fitting characteristics which, in turn, can affect the level 
of employee protection afforded by the respirators. In this regard, an 
important question is whether available WPF and SWPF studies 
demonstrate sufficient variability in protection between and among 
filtering facepiece and elastomeric respirators to warrant different 
APF levels.
    OSHA reviewed available WPF and SWPF studies that determined APFs 
for separate models of half-mask respirators based on each respirator's 
performance. These studies usually determine a protection factor for 
each respirator user (e.g., an employee in a WPF study, or a member of 
a panel of respirator users in a SWPF study) who participates in the 
study, with each of these values expressed as the concentration of 
challenge agent outside the respirator (Co) divided by the 
concentration of that agent inside the respirator (Ci), 
i.e., Co/Ci. After collecting these values, a 
statistical analysis determines the geometric distribution of the 
values; the overall APF for the respirator is the estimated value that 
lies at the fifth percentile of the geometric distribution. Listed in 
the table below are the WPF studies on filtering facepiece and 
elastomeric respirators reviewed by the Agency.

----------------------------------------------------------------------------------------------------------------
                                                                                     Geometric
WPF studies for filtering facepieces (by name of    Sample size   Geometric mean     standard     5th percentile
     authors and model of respirator tested)                                         deviation          WPF
----------------------------------------------------------------------------------------------------------------
Cohen (Ex. 1-64-11):
    Prototype Mercury (disposable respirator)...              26              28  ..............               5
Albrecht et al. (Ex. 1-64-23):
    3M 8710.....................................              13              81            1.99              25
    3M 9910.....................................              13             107            2.50              20
    3M 9920.....................................              10             223            2.38              45
Nelson and Dixon (Ex 1-64-54):
    3M 8710.....................................              18             310             5.3              20
    3M 9910.....................................              14             580             4.2              55
    AO R1050....................................               7              52             4.2               5
Reed et al. (Ex. 1-64-61):
    3M 9910.....................................              19              18             3.1               3
Johnston and Mullins (Ex. 1-64-34):
    3M 8715 (with aluminum particulate).........              10             145             2.3              32
    3M 8715 (with titanium particulate).........              14              59             1.7              24
    3M 8715 (with silicon particulate)..........              14             172             3.1              24
Colton et al. (Ex. 1-64-15):
    3M 9906.....................................              23              27             1.5              13
Colton et al. (Ex. 1-64-16):
    3M 9970 (with lead particulate).............              62             415             4.4              36
    3M 9970 (with zinc particulate).............              62             681             5.6              40
Myers and Zhuang (Ex. 1-64-51) (conducted in a
 brass foundry):
    3M 9920 (with zinc particulate).............              20             108             5.2               7
Myers and Zhuang (Ex. 3-14) (conducted in a
 steel mill):
    3M 8710 (with iron particulate).............              10             377             3.7              44
    Gerson 1710 (with iron particulate).........              11             123             2.7              24
Colton and Mullins (Ex. 1-146):
    3M 9920 and 3M 9925.........................              32             147             2.5              33
Wallis et al. (Ex. 1-64-70):
    3M 8710.....................................              70              50             3.5             7.5
Lenhart and Decker (Ex. 1-64-56):
    3M 9920.....................................               5  ..............  ..............              12
    3M 9970 (two separate studies)..............               2  ..............  ..............       86 and 98
Gaboury and Burd (Ex. 1-64-24):
    AO, Willson, Survivair......................              18              47             2.5               9
Gavin et al. (Ex. 1-64-22):
    North 7709 (with OV cartridge)..............              63              75             3.1            11.7
Weber and Mullins (Ex. 3-15):
    3M 5000 (with OV cartridge).................              46            39.7            2.14              11
Myers and Zhuang (Ex. 1-64-51) (conducted in a
 brass foundry):
    AO 5-Star (with DFM filter).................               6              98             5.8               5
    MSA Combo II (with DFM filter)..............               9             163             3.1              26
    Scott 65 (with DFM filter)..................               6              94             4.8               7
Myers and Zhuang (Ex. 3-14) (conducted in a
 steel mill):
    AO 5-Star (with DM filter)..................              11             280             2.7              56
    MSA Combo II (with DM filter)...............               8             427             4.3              39
    Scott 65 (with DM filter)...................              11             252             2.9              45
Myers and Zhuang (Ex. 1-64-52) (conducted in a
 paint-spraying facility):
    AO 5-Star (with HEPA or OV filter)..........              38           2,211  ..............             171
    MSA Combo II (with HEPA or OV filter).......              38           4,580  ..............             437
    Scott 65 (with HEPA or OV filter)...........              38           6,630  ..............           1,121
Lenhart and Campbell (Ex. 1-64-42):
    MSA Combo (with HEPA filter)................              25             180             4.1              18
Albrecht et al. (Ex. 1-64-23):
    3M Easi-Air 7000 (with HEPA filter).........               8              56            1.35              31
    3M Easi-Air 7000 (with DM filter)...........               6              68            1.66              28
Dixon and Nelson (Ex. 1-64-54):
    Survivair 2000 and MSA Combo II (with DFM                 17             240             6.3              12
     filter)....................................

[[Page 34096]]

 
    Survivair 2000 and MSA Combo II (with HEPA                14              94             3.0              16
     filter)....................................
    North 7700 (with HEPA filter)...............              14             250             6.9              11
Dixon and Nelson (Ex. 1-64-19):
    Survivair 2000 (with HEPA or OV filter).....              37           3,400             3.8             390
Colton et al. (Ex. 1-64-13):
    3M 6000 (with HEPA filter and cadmium                     25             333            4.18              32
     particulate)...............................
    3M 6000 (with HEPA filter and lead fume)....              31             129            3.15              19
Colton and Bidwell (Ex. 4-10-4):
    3M 7000 (with 7255 HEPA mechanical filter)..              21           1,006            4.65              80
    3M 7000 (with 2040 HEPA electrostatic                     22             562             3.5              71
     filter)....................................
----------------------------------------------------------------------------------------------------------------

    OSHA found only one SWPF study on half-mask air-purifying 
respirators. In 1987, Skaggs, Loibl, Carter, and Hyatt (Ex. 1-38-3) of 
LANL performed a SWPF study that included laboratory testing of the MSA 
Comfo II half-mask air-purifying elastomeric respirator. The geometric 
mean fit factors they measured during simulated work exercises ranged 
from 800 to 5,700 for this half-mask. These results appear to 
complement the WPF results discussed in the following paragraph.
    The summary statistics for WPF studies of filtering facepieces and 
elastomeric half-masks presented in the previous tables show little 
difference between these two major subclasses of half-mask respirators. 
Most importantly, the estimated protection factors for these two 
subclasses evidence considerable overlap. In addition, both tables show 
that many respirators in each class received estimated protection 
factors above 10, while a few respirators performed below that level. 
Accordingly, the WPF studies overall support assigning an APF of 10 for 
this respirator class (i.e., half-masks), which consists of quarter 
masks, filtering facepieces, and elastomeric half-mask respirators. 
OSHA could find no studies on the performance of quarter masks, but 
just as in the 1992 ANSI standard (Ex. 1-50) has included quarter masks 
with half-masks.
    The statistical analyses of these studies performed by Dr. Kenneth 
Brown (see section IV above) corroborate these conclusions. These 
analyses could not differentiate between filtering facepieces and 
elastomeric half-masks, which justifies combining the study data for 
these two subclasses into a single class for a subsequent APF 
determination. This determination showed that nearly 96% of the WPF 
data in these combined studies were at or above an APF of 10.
3. Full Facepiece Air-Purifying Respirators
    Historical development of APFs for full facepiece air-purifying 
respirators. In 1976, Ed Hyatt of LANL developed an APF table that 
included this respirator class (Ex. 2). In this report, Hyatt used the 
results from quantitative fit testing to assess six models of full 
facepiece negative pressure air-purifying respirators equipped with 
HEPA filters. Five of these respirators achieved a protection factor of 
at least 100 for 95% of the respirator users; the sixth respirator 
attained this level of protection for 70% of the users. Based on the 
results for the sixth respirator, Hyatt recommended an APF of 50 for 
the respirator class as a whole.
    The 1980 ANSI standard listed an APF of 100 for full facepiece air-
purifying respirators with DFM filters. ANSI increased the APF for this 
respirator class from 50 to 100 because the poorly performing 
respirator in Hyatt's study was no longer in production. Using the 1976 
LANL quantitative fit-testing results, the 1980 ANSI standard increased 
this APF to a maximum of 1,000 when the respirator used HEPA filters 
and the respirator users received quantitative fit testing.
    Based on Hyatt's 1976 data, the 1987 NIOSH RDL recommended that 
this respirator class receive an APF of 50 when equipped with a HEPA 
filter, and an APF of 10 when using DFM filters. NIOSH developed the 
lower APF of 10 for respirators equipped with DFM filters after it 
tested the efficiency of these filters. In the absence of workplace 
protection factor studies of full facepiece respirators, NIOSH based 
these APFs on results from earlier quantitative fit testing performed 
by LANL on panels of respirator users.
    The 1992 ANSI standard retained the 1980 ANSI standard's APF of 100 
for full facepiece air-purifying respirators, but required that 
respirator users perform fit testing and achieve a minimum fit factor 
of 1,000 prior to using the respirators; in this regard, quantitative 
fit testing was necessary because no qualitative fit test could achieve 
a fit factor of 1,000. The ANSI standard kept this APF because the ANSI 
committee found that no new WPF or SWPF studies had been performed for 
this respirator class since it last issued APFs in 1980.
    The following table summarizes the previous APFs assigned to full 
facepiece air-purifying respirators, beginning with Hyatt's studies at 
LLNL in 1976 through the 1992 ANSI standard.

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                           APFs
  Full facepiece air-purifying  ------------------------------------------------------------------------------------------------------------------------
          respirators                                                                                                                        1992 ANSI
                                            LANL (1976)                     1980 ANSI standard                  NIOSH RDL (1987)             standard
--------------------------------------------------------------------------------------------------------------------------------------------------------
All respirators in the class...  50 (with HEPA filter)............  10 (with QLFT)...................  10 (with DFM filter).............             100
                                                                    100 max. (with QNFT).............  50 (with HEPA filter)............
--------------------------------------------------------------------------------------------------------------------------------------------------------

    OSHA's proposed APFs for full facepiece air-purifying respirators. 
Although the 1992 ANSI standard assigned an APF of 100 to full 
facepiece air-purifying respirators, OSHA believes that studies 
completed after 1992 indicate that an APF of 100 is too high. Colton, 
Johnston, Mullins, and Rhoe (Ex. 1-64-14) assessed the protection 
afforded to 13 employees over a four day period by the 3M 7800 full 
facepiece air-purifying respirator equipped with a HEPA filter. In this 
WPF study, the employees performed their regular tasks in the blast 
furnace,

[[Page 34097]]

reverberatory furnace, and casting and warehouse areas of a lead 
smelter while the authors sampled lead dust and fumes inside and 
outside the respirator. The authors found a fifth percentile protection 
factor of 95 for the combined samples, but concluded that the 
respirator provided reliable protection at protection factors in excess 
of 50.
    Skaggs, Loibl, Carter, and Hyatt (Ex. 1-38-3) completed the only 
SWPF study on a full facepiece air-purifying respirator at LANL; this 
study measured the protection afforded by the MSA Ultra Twin with a 
HEPA filter. Ten members of the respirator test panel used the 
respirator under varying temperature and humidity conditions in a test 
chamber while performing simulated work tasks. The authors reported fit 
factors with geometric means ranging from 1,000 to 5,300 for this 
respirator. However, 23 of the 60 measurements reported were less than 
1,000, 7 were less than 100, and 3 of these measurements were less than 
50.
    After carefully reviewing these studies, OSHA is proposing an APF 
of 50 for full facepiece air-purifying respirators. The proposed APF 
agrees with the conclusion of Colton, Johnston, Mullins, and Rhoe (Ex. 
1-64-14) that this class of respirators provides reliable protection at 
an APF of 50. Additionally, the geometric mean simulated work fit 
factors reported by Skaggs, Loibl, Carter, and Hyatt (Ex. 1-38-3) were 
low for a SWPF study, and a few of the individual measurements were 
below an APF of 50; in the workplace, the fifth percentile APF for this 
respirator may fall well below 100. Therefore, in view of the paucity 
of data reported for this class of respirators, and the constraints 
imposed by the available studies, the Agency is proposing a 
conservative APF that it believes would afford employees an adequate 
and consistent level of respirator protection in the workplace.
    Importantly, an APF of 50 corresponds with the APF assigned to full 
facepiece air-purifying respirators by OSHA in its substance specific 
standards, and by NIOSH in its 1987 RDL. In determining that an APF of 
50 was appropriate for protecting employees against the contaminants 
identified in its substance specific standards, the Agency reviewed the 
existing scientific and technical information, and carefully considered 
comments in the records. OSHA believes that the information now 
available does not justify revising the previous APF determined for its 
substance specific standards. To ensure that the final APF for this 
class of respirators provides employees with appropriate protection, 
the Agency requests that commenters submit to the record any additional 
WPF and SWPF studies that may be available on full facepiece air-
purifying respirators.
4. Powered Air-Purifying Respirators (PAPRs)
    Historical development of APFs for PAPRs. In 1976, Ed Hyatt of LANL 
gave PAPRs equipped with high efficiency filters, regardless of 
facepiece type, a protection factor of 1,000. In doing so, Hyatt 
assumed, based on quantitative fit tests, that both tight-fitting and 
loose-fitting facepiece PAPRs would always maintain a positive pressure 
inside the facepiece.
    The committee responsible for drafting the 1980 ANSI standard 
assigned an APF of 3,000 to PAPRs equipped with high efficiency 
filters. When the respirators used DFM filters, they received an APF of 
100. The ANSI committee did not require fit testing for PAPRs because 
it assumed, as did Hyatt, that these respirators would maintain 
positive pressure during use.
    The 1987 NIOSH RDL assigned an APF of 25 to half-mask PAPRs after 
NIOSH reviewed the results of two WPF studies that it conducted on 
these respirators (Ex. 1-64-42 and 1-64-46). The RDL also gave loose-
fitting PAPRs with hoods or helmet an APF of 25 based on data from two 
studies performed by Myers, Peach, Cutright, and Iskander (Exs. 1-64-47 
and 1-64-48). However, the RDL recommended an APF of 50 for other PAPRs 
equipped with a tight-fitting facepiece or a hood or helmet, as well as 
high efficiency filters or gas-vapor cartridges used in combination 
with high efficiency filters.
    The committee developing the 1992 ANSI standard updated the APFs 
specified in the 1980 ANSI standard. Accordingly, the committee 
recommended an APF of 50 for tight-fitting half-mask PAPRs based on the 
same WPF studies used by NIOSH in developing the 1987 RDL. Tight-
fitting full facepiece PAPRs received an APF of 100 when equipped with 
dust filters (based on performance limitations of the filters), and an 
APF of 1,000 when used with HEPA filters. While the ANSI committee 
retained an APF of 25 for loose-fitting facepiece PAPRs, including 
loose-fitting hoods and helmets, it treated tight-fitting PAPRs with 
hoods or helmets much as it did tight-fitting full facepiece PAPRs 
(i.e., by assigning them an APF of 100 when used with a dust filter, 
and an APF of 1,000 when equipped with a HEPA filter).
    The following table summarizes the previous APFs assigned to PAPRs, 
beginning with Hyatt's studies at LANL in 1976 through the 1992 ANSI 
standard.

----------------------------------------------------------------------------------------------------------------
                                                                       APFs
      Powered air-purifying      -------------------------------------------------------------------------------
       respirators (PAPRs)           LANL
                                    (1976)       1980 ANSI standard       NIOSH RDL (1987)    1992 ANSI standard
----------------------------------------------------------------------------------------------------------------
Half-mask.......................       1,000  100 (with DFM filter),    50 (with HEPA        50.
                                               3,000 max. (with HEPA     filter).
                                               filters).
Full facepiece..................       1,000  100 (with DFM filter),    50 (with HEPA        100 (with dust
                                               3,000 max. (with HEPA     filter).             filter), 1,000
                                               filters).                                      (with HEPA
                                                                                              filter).
Hoods or helmets................       1,000  100 (with DFM filter),    50 (with HEPA        100 (with dust
                                               3,000 max. (with HEPA     filter).             filter), 1,000
                                               filters).                                      (with HEPA
                                                                                              filter).
Loose-fitting facepiece.........       1,000  100 (with DFM filter),    25 (with any         25.
                                               3,000 max. (with HEPA     filter).
                                               filters).
----------------------------------------------------------------------------------------------------------------

    OSHA's proposed APFs for half-mask PAPRs. In 1983, Meyers and Peach 
performed a WPF study on tight-fitting half-mask and full facepiece 
PAPRs in a silica-bagging operation (Ex. 1-64-46). The geometric mean 
protection factors for each of the seven employees who used the half-
mask PAPRs ranged from 19 to 193, with a geometric mean protection 
factor of 54 for the entire sample. The authors attributed the poor 
performance of the half-mask PAPRs to leakage around the filter 
assembly connection where it attached to the PAPR blower housing, as 
well as to inadequate facepiece fit.
    Lenhart and Campbell of NIOSH in 1984 conducted another WPF study 
of tight-fitting half-mask PAPRs used by employees in the sinter plant 
and furnace areas of a primary lead smelter

[[Page 34098]]

(Ex. 1-64-42). For the entire sample, the authors reported a geometric 
mean protection factor of 380 and a fifth-percentile protection factor 
of 58.
    Two SWPF studies also evaluated tight-fitting half-mask PAPRs. 
Skaggs, Loibl, Carter, and Hyatt (Ex. 1-38-3) used fit testing to 
assess the performance of the respirators in a test chamber under 
variable temperature and humidity conditions. They found that the 
geometric mean protection factor for the entire sample ranged from 
14,200 to 20,000. In the second SWPF study, da Roza, Cadena-Fix, and 
Kramer tested a panel of respirator users who exercised on a treadmill 
at different work rates (Ex. 1-64-94). The geometric mean protection 
factor for the entire sample (i.e., combining respirator performance at 
all work rates) was 5,000.
    The following table provides a summary of the WPF and SWPF studies 
for tight-fitting half-mask PAPRs.

----------------------------------------------------------------------------------------------------------------
                                                                                     Geometric
   WPF studies for half-mask PAPRs (by name of      Sample size   Geometric mean     standard     5th percentile
  authors and type/model of respirator tested)                                       deviation          WPF
----------------------------------------------------------------------------------------------------------------
Lenhart and Campbell (Ex. 1-64-42), MSA.........              25             380             2.6              58
Myers and Peach (Ex. 1-64-46), PAPR                           10              54            2.44  ..............
 (manufacturer and model not specified).........
----------------------------------------------------------------------------------------------------------------


----------------------------------------------------------------------------------------------------------------
                                                                                     Geometric
  SWPF studies for half-mask PAPRs (by name of      Sample size   Geometric mean     standard     5th percentile
  authors and type/model of respirator tested)                                       deviation         SWPF
----------------------------------------------------------------------------------------------------------------
Skaggs et al. (Ex. 1-38-3), MSA with Comfo II                 60   14,200-20,000  ..............  ..............
 facepiece......................................
da Roza et al. (Ex. 1-64-94), MSA with Comfo               \1\ 6       \2\ 5,000  ..............  ..............
 facepiece......................................
----------------------------------------------------------------------------------------------------------------
\1\ The six respirator users of the test panel exercised on a treadmill.
\2\ The geometric mean is for all exercise rates combined.

    In arriving at a proposed APF of 50 for tight-fitting half-mask 
PAPRs, OSHA relied to a large extent on the WPF study conducted by 
Lenhart and Campbell. This study was well controlled and collected data 
under actual workplace conditions; these conditions ensure that the 
results are reliable and represent the protection employees likely 
would receive under conditions of normal respirator use. The Agency did 
not consider the Meyers and Peach WPF study for this purpose because of 
problems involving filter assembly leakage and poor facepiece fit 
reported by the authors; consequently, the abnormally high levels of 
silica measured inside the mask would most likely underestimate the 
true protection afforded by the respirator. The two SWPF studies 
reported much higher geometric mean protection factors than did the WPF 
study performed by Lenhart and Campbell. However, OSHA believes that 
the higher protection factors reported for these SWPF studies are 
consistent with the proposed APF of 50 based on data obtained for this 
respirator class in the Lenhart and Campbell WPF study because SWPF 
studies typically report significantly higher protection factors than 
WPF studies of the same respirator. In addition, the proposed APF 
duplicates the APFs assigned to tight-fitting half-mask respirators by 
the 1987 NIOSH RDL and the 1992 ANSI standard, both of which based 
their APF determinations on data reported in the existing scientific 
literature, as well as the opinions of well known experts on 
respiratory protection.
    OSHA's proposed APFs for full facepiece PAPRs and PAPRs with hoods 
or helmets. Two WPF studies determined protection factors for tight-
fitting full facepiece PAPRs. Myers and Peach conducted the first of 
these studies in 1983 (Ex. 1-64-46); OSHA described this study in its 
earlier discussion of tight-fitting half-mask PAPRs. As noted in this 
discussion, the Agency did not use the results of this study because of 
problems involving filter assembly leakage and poor facepiece fit 
reported by the authors. The second WPF study, by Colton and Mullins, 
reported a geometric mean protection factor of 4,226, and a fifth 
percentile protection factor of 728 for employees in a secondary lead 
smelter (Ex. 1-64-12). Thirty-four samples in this study had no 
detectable lead inside the respirators; therefore, the authors used the 
limit of detection for lead as a proxy for the concentration of lead 
inside the facepiece. When the authors corrected their data analysis by 
including these samples, the geometric mean protection factor increased 
to 8,843, and the fifth percentile protection factor rose to 1,335. No 
SWPF studies on full facepiece PAPRs were available.
    One WPF study and one SWPF study are available for tight-fitting 
PAPRs with hoods or helmets. In the WPF study, Keys, Guy, and Axon, 
determined the protection afforded to employees in a pharmaceutical 
manufacturing plant by three different respirators in this class (Ex. 
1-64-40). The fifth percentile protection factors for these respirators 
were 997, 1,197, and 1,470. Johnson, Biermann, and Foote of LLNL and 
Cohen, Hecker, and Mattheis of the Organization Resources Counselors 
(ORC) performed the single SWPF study (referred to here as ``the ORC-
LLNL SWPF Study'') in which they collected 576 test samples from four 
different PAPRs with hoods or helmets, and equipped with bibs (Ex. 3-4-
2). The lowest protection factor among the 576 test samples was 11,000; 
overall, the 576 test samples had a fifth percentile protection factor 
greater than 250,000.
    The following tables summarize the WPF studies for tight-fitting 
full facepiece PAPRs, and the WPF and SWPF studies involving PAPRs with 
hoods or helmets.

----------------------------------------------------------------------------------------------------------------
                                                                                     Geometric
WPF studies for full facepiece PAPRs (by name of    Sample size   Geometric mean     standard     5th percentile
     authors and model of respirator tested)                                         deviation          WPF
----------------------------------------------------------------------------------------------------------------
Colton and Mullins (Ex. 1-64-12) 3M W-3205
 Whitecap (with 3M 7800 full facepiece and HEPA
 filter):
    Study 1\1\..................................              20           4,226             2.9             728

[[Page 34099]]

 
    Study 2.....................................              55           8,843             3.2           1,335
Myers and Peach (Ex. 1-64-46) Full facepiece                  10              54            2.44  ..............
 PAPR (manufacturer and model not specified)....
----------------------------------------------------------------------------------------------------------------
\1\ Study 1 consisted of 20 samples with Ci values over the detection limit, while Study 2 consisted of 34
  samples that had Ci values below the detection limit; for analytic purposes, the investigators assigned these
  34 samples a Ci value equal to the detection limit.


----------------------------------------------------------------------------------------------------------------
                                                                                     Geometric
 WPF studies for PAPRs with hoods or helmets (by    Sample size   Geometric mean     standard     5th percentile
 name of authors and model of respirator tested)                                     deviation          WPF
----------------------------------------------------------------------------------------------------------------
Keys et al. (Ex. 1-64-40):
    Racal Breathe Easy 10 (hood, double bib,                  29          11,137             3.9           1,197
     HEPA filter)...............................
    Bullard Quantum (hood, double bib, HEPA                    9           9,574             3.1           1,470
     filter)....................................
    3M Whitecap II (helmet, double bib, HEPA                  22          42,260             9.8             997
     filter)....................................
----------------------------------------------------------------------------------------------------------------


----------------------------------------------------------------------------------------------------------------
  SWPF studies for PAPRs with hoods or helmets (by                         Geometric median     5th percentile
   name of authors and model of respirator tested)      Range of SWPFs           SWPF                SWPF
----------------------------------------------------------------------------------------------------------------
ORC-LLNL SWPF Study (Ex. 3-4):
    3M Whitecap (helmet with bib and HEPA filter)...  140,000-250,000  250,000
                                                                >250,000
    3M Snapcap (Tyvek hood with bib and HEPA filter)  11,000-  250,000  170,000
                                                                 250,000                                -210,000
    Racal BE-5 Clear PVC (hood with bib and HEPA      11,000-  250,000  250,000
     filter)........................................             250,000
    Racal BE-10 (Tyvek hood with bib and HEPA         94,000-  250,000  246,000-250,000
----------------------------------------------------------------------------------------------------------------

    OSHA is proposing an APF of 1,000 for full facepiece PAPRs and 
PAPRs with hoods or helmets. With regard to full facepiece PAPRs, the 
corrected fifth percentile protection factor of 1,335 reported by 
Colton and Mullins in their WPF study fully supports the proposed APF. 
The WPF study of PAPRs with hoods or helmets by Keys, Guy, and Axon 
justifies the proposed APF of 1,000 for this respirator class. These 
authors reported that the average fifth percentile protection factor 
for the three respirators tested in their study was well over 1,000. 
Moreover, the ORC-LLNL SWPF Study (Ex. 3-4), in which this class of 
respirators received extremely high fifth percentile protection 
factors, lends substantial validation to OSHA's proposed APF. In 
addition, the proposed APFs for full facepiece PAPRs and PAPRs with 
hoods or helmets corresponds with the APFs assigned to these respirator 
classes in the 1992 ANSI standard; ANSI made these APF determinations 
only after a careful review and discussion of the available research by 
a panel of respirator experts. While the proposed APF for these 
respirators is much higher than the APF recommended in the 1987 NIOSH 
RDL, the Agency believes that the WPF and SWPF studies conducted on 
these respirators since publication of the RDL justify the proposed 
increase.
    Footnote 4 of the proposed APF table states that ``* * * only 
helmet/hood respirators that ensure the maintenance of a positive 
pressure inside the facepiece during use, consistent with performance 
at a level of protection of 1000 or greater, receive an APF of 1,000.'' 
The footnote continues, ``All other helmet/hood respirators are treated 
as loose-fitting facepiece respirators and receive an APF of 25.'' OSHA 
is proposing that respirators from this class be able to demonstrate 
that they maintain a positive pressure inside the facepiece during use 
and achieve a level of protection of 1000 or greater. Available WPF and 
SWPF studies have found that some of these respirators were shown to 
only achieve protection factors well below 1,000 (Exs. 3-4, 3-5). In 
all likelihood, the burden of conducting any testing would fall on 
respirator manufacturers, but the employer would be responsible for 
selecting a properly tested respirator, thereby assuring employees that 
they will receive adequate protection against toxic hazards.
    OSHA's proposed APFs for loose-fitting PAPRs. A number of WPF and 
SWPF studies are available for loose-fitting facepiece PAPRs. An 
important purpose of these studies was to determine if APFs differed 
between loose-fitting facepiece PAPRs and PAPRs with tight-fitting 
hoods or helmets. The NIOSH WPF study by Myers, Peach, Cutright, and 
Iskander (Ex. 1-64-47) was the first to report that loose-fitting 
facepiece PAPRs did not perform at an APF of 1,000, the value 
determined by Ed Hyatt in 1976 after quantitatively fit testing a panel 
of respirator users. A follow-up study by Myers, Peach, Cutright, and 
Iskander (Ex. 1-64-48) reported a fifth percentile protection factor of 
25 for this respirator class.
    A WPF study conducted later by Albrecht, Gosselink, Wilmes, and 
Mullins (Ex. 1-64-23) reported a fifth percentile protection factor of 
42 for the 3M Airhat, a loose-fitting facepiece PAPR with a helmet. 
Stokes, Johnston, and Mullins (Ex. 1-64-66) performed a WPF study in a 
roofing granule production plant using the 3M Airhat; they found a 
fifth percentile protection factor of 95. However, when employees used 
the respirator with a Tyvek shroud, the fifth percentile protection 
factor increased to 1,615. Gaboury and Burd (Ex. 1-64-24) reported a 
fifth percentile protection factor of 275 in a WPF study in which 
employees in an aluminum smelter wore a Racal Breathe Easy loose-
fitting facepiece PAPR with a helmet. Collia, Colton, and Bidwell (Ex. 
3-5) found a fifth percentile protection factor of 315 in a WPF study 
performed on the 3M Breathe Easy 12 PAPR with a loose-fitting head 
cover.
    OSHA evaluated three SWPF studies addressing the performance of 
loose-fitting facepiece PAPRs with hoods or helmets. Skaggs, Loibl, 
Carter, and Hyatt (Ex. 1-38-3) reported geometric mean protection 
factors ranging from 1,900 to 5,600 for the 3M Airhat, and from 1,200 
to 3,500 for the Racal AH3 PAPR with a loose-fitting helmet. A study by 
da Roza, Cadena-Fix, and Kramer (Ex. 1-64-94) found geometric mean 
protection factors ranging from 10 to 10,000, and from 100 to 20,000, 
for the two loose-fitting facepiece PAPRs with helmets they tested.

[[Page 34100]]

    Johnson, Biermann, and Foote of LLNL and Cohen, Hecker, and 
Mattheis of ORC (Ex. 3-4) assessed the performance of one loose-fitting 
facepiece PAPR with a Tyvek head cover as part of the ORC-LLNL SWPF 
Study; the results of this study reported three APFs below 10,000, with 
the lowest value being 240. The fifth percentile protection factor for 
this respirator ranged from 150,000 to 230,000.
    The following tables summarize the WPF and SWPF studies for loose-
fitting facepiece PAPRs with hoods or helmets.

----------------------------------------------------------------------------------------------------------------
WPF studies for loose-fitting facepiece PAPRs                                     Geometric
with hoods or helmets (by name of authors and    Sample size   Geometric mean     standard       5th percentile
         model of respirator tested)                                              deviation           WPF
----------------------------------------------------------------------------------------------------------------
Myers et al.(Ex. 1-64-47):
    3M W-344 (helmet with HEPA filter).......              23             165            3.57                 26
    Racal AH 3 (helmet with HEPA filter).....              23             205            2.83                 26
Albrecht et al. (Ex. 1-64-23) 3M Airhat                     7             199            2.36                 42
 (helmet with HEPA filter)...................
Myers et al. (Ex. 1-64-48):
    3M W-316 (helmet with DM filter).........              22             135            1.89                 25
    Racal AH 5 (helmet with DM filter).......              24             120            2.64                 25
Gaboury and Burd (Ex. 1-64-24) Racal Breathe               20           1,414            2.51                275
 Easy I (helmet with HEPA or OV filter)......
Collia et al. (Ex. 3-5) 3M Breathe Easy 12                 41           2,523  ..............                315
 (Tyvek head cover with HEPA filter).........
Stokes et al. (Ex. 1-64-66):
    3M Airhat (helmet) with:
        HEPA filter (total)\1\...............              12           5,370             3.0                762
        DM filter (without shroud)...........              27             877             5.2                 53
        DM filter (with shroud)..............              18          11,792             3.1              1,615
        DM filter (total)....................              45           2,480             7.0                95
----------------------------------------------------------------------------------------------------------------
\1\ The total consists of the shroud and no-shroud samples combined.


----------------------------------------------------------------------------------------------------------------
   SWPF studies for loose-fitting facepiece
   PAPRs with hoods or helmets (by name of       Sample size   Geometric mean     Geometric      5th percentile
   authors and model of respirator tested)                                         median             SWPF
----------------------------------------------------------------------------------------------------------------
Skaggs et al. (Ex. 1-38-3):
    3M Airhat W-344 (helmet).................              60     1,900-5,600  ..............  .................
    Racal AH3 Airstream (helmet).............              60     1,200-3,500  ..............  .................
da Roza et al. (Ex. 1-64-94):
    3M Airhat W-344 (helmet).................           \1\ 6       10-10,000  ..............  .................
    Racal Breathe-Easy 1 (helmet)............               6      100-20,000  ..............  .................
ORC-LLNL SWPF Study (Ex. 3-4):
    Racal BE-12 (Tyvek head cover)...........             144     240-250,000         250,000   150,000-230,000
----------------------------------------------------------------------------------------------------------------
\1\ Used same panel of six respirator users for both respirators; panel exercised on treadmill at 80% cardiac
  capacity.

    OSHA is proposing an APF of 25 for loose-fitting PAPRs with hoods 
or helmets, which is consistent with both WPF studies conducted by 
Myers, Peach, Outright, and Iskander (Ex. 1-64-47 and 1-64-48), as well 
as the APFs for this respirator class established by the 1987 NIOSH RDL 
and by the 1992 ANSI standard. The extreme variability of the fifth 
percentile protection factors in the WPF studies warrants a 
conservative approach in proposing an APF for this respirator class. In 
this regard, seven of the 11 WPF studies found fifth percentile 
protection factors of less than 100, and five of these APFs were below 
50. The Agency believes that a proposed APF of 25 would provide 
employees who use these respirators with an adequate safety margin in 
view of the unreliability of the protection factors found for this 
respirator class.
    The geometric means reported by Skaggs, Loibl, Carter, and Hyatt 
(Ex. 1-38-3) were low for a SWPF study, as were a number of the 
geometric means determined by de Rosa, Cadena-Fix, and Kramer (Ex. 1-
64-94) in their SWPF assessments. In the workplace, these low geometric 
mean SWPFs likely would translate into fifth percentile WPFs of less 
than 50. Therefore, the limited and highly variable data in the SWPF 
studies support OSHA's conclusion that a conservative APF of 25 would 
afford employees an adequate and consistent level of respirator 
protection in the workplace.
5. Supplied-Air Respirators (SARs)
    Historical development of APFs for SARs. SARs operate in one of 
three modes--demand, continuous flow, or pressure demand. Demand or 
pressure demand respirators have either a tight-fitting half-mask or a 
tight-fitting full facepiece, while continuous flow respirators have 
either a tight-fitting, or a loose-fitting, hood or helmet, or a tight-
fitting half-mask or full facepiece.
    In 1976, Ed Hyatt of LANL published the initial protection factors 
for SARs (Ex. 2). In making these determinations, Hyatt gave an APF of 
10 to half-mask SARs operated in the demand mode, while full facepiece 
SARs received an APF of 50 in the demand mode. These APFs are the same 
APFs that Hyatt assigned to negative pressure half-masks, and full 
facepiece, air-purifying respirators. Hyatt based the APF of 10 for 
half-mask SARs operating in the demand mode on LANL studies performed 
in 1971 and 1972 on a respirator test panel wearing eight half-mask 
air-purifying respirators equipped with HEPA filter. In determining an 
APF of 50 for full facepieces, Hyatt relied on LANL studies in which a 
respirator test panel consisting of 31 firemen wore full facepiece 
SCBAs operating in the demand mode.
    Hyatt regarded SARs that operate in a positive pressure mode to be 
more protective than SARs used in a negative pressure mode; therefore, 
he assigned half-mask and full facepiece SARs that function in the 
continuous flow, pressure demand, or other positive pressure modes APFs 
of 1,000 and 2,000, respectively; the half-mask respirators received a 
lower APF than the full facepiece respirators because

[[Page 34101]]

Hyatt considered a half-mask to be less stable on the face than a full 
facepiece. SARs with hoods or helmets operated in continuous flow mode 
received an APF of 2,000, consistent with the APF Hyatt gave to full 
facepiece SARs operating in the continuous flow or pressure demand 
mode.
    The 1980 ANSI standard differentiated APFs for some SARs depending 
on the type of fit testing performed. Accordingly, half-mask and full 
facepiece SARs used in the demand mode received APFs of 10 and 100, 
respectively, when qualitatively fit tested. When tested 
quantitatively, the APFs for these respirators were the protection 
factors achieved during fit testing, with the APF limited to the sub-
IDLH value \10\ of the hazardous substance in the workplace.
---------------------------------------------------------------------------

    \10\ The concentration of the hazardous substance just below its 
IDLH value.
---------------------------------------------------------------------------

    Half-mask or full facepiece SARs that functioned in continuous flow 
or pressure demand modes required no fit testing because of their 
positive pressure operation; consequently, these respirators received 
an APF limited only to the sub-IDLH value of the hazardous substance in 
the workplace when used without an auxiliary air supply or escape 
bottle (i.e., the ``escape configuration''). When equipped in an escape 
configuration, these respirators had a maximum APF of 10,000. 
Continuous flow or pressure demand SARs with hoods or helmets also 
received a maximum APF of 10,000 when not used in an escape 
configuration; however, when operated in a escape configuration, the 
maximum APF for these respirators was of 10,000+ (i.e., employees could 
use them to escape from IDLH atmospheres).
    The 1987 NIOSH RDL recommended APFs of 10, 50, and 1,000, 
respectively, for half-mask SARs when operated in demand, continuous 
flow, and positive pressure (including pressure demand) modes. All SARs 
with hoods or helmets received an APF of 25 when used in the 
continuous-flow mode. The RDL assigned full facepiece SARs an APF of 50 
when they functioned in the demand or continuous flow mode, an APF of 
2,000 when operated in the pressure demand or other positive pressure 
mode, and a maximum APF of 10,000 when used in the pressure demand mode 
with an auxiliary SCBA.
    The 1992 ANSI standard did not set different APFs for the same 
class of respirator based on the type of fit testing conducted because 
WPF studies performed after publication of the 1980 ANSI standard did 
not support this practice. After comparing the operational 
characteristics of half-mask and full facepiece SARs to half-mask and 
full facepiece air-purifying respirators, the 1992 ANSI standard gave 
APFs of 10 and 100, respectively, to half-mask and full facepiece SARs 
when operated in the demand mode. Pressure demand and continuous flow 
half-mask SARs received an APF of 50, consistent with their operational 
similarities with half-mask PAPRs. Full facepiece continuous flow SARs 
received an APF of 1,000, determined from their operational analogy to 
SARs having tight-fitting hoods or helmets. Based on their operational 
similarities to loose-fitting continuous flow PAPRs, the committee 
drafting the 1992 ANSI standard gave loose-fitting facepiece SARs 
operated in the continuous flow mode an APF of 25.
    The following table summarizes the APFs given to the various 
classes of SARs (i.e., half-mask, full facepiece, tight-fitting with 
hoods or helmets, and loose-fitting facepiece), beginning with Hyatt's 
studies at LLNL in 1976 through the 1992 ANSI standard.

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                 APFs
                SARs                 -----------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      LANL (1976)                    1980 ANSI standard                  NIOSH RDL (1987)                          1992 ANSI standard
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Half-mask...........................  10 (demand)................................  10 (demand; with QLFT)  10 (demand)................................  10 (demand).
                                      1,000 (continuous flow)....................  Same as QNFT factor     50 (continuous flow).......................  50 (continuous flow).
                                                                                    (demand; sub-IDLH
                                                                                    value max.).
                                      1,000 (pressure demand)....................  Sub-IDLH (continuous    1,000 (pressure demand)....................  50 (pressure demand).
                                                                                    flow or pressure
                                                                                    demand; no escape
                                                                                    configuration).
                                                                                   10,000 max. (with
                                                                                    escape configuration).
Full facepiece......................  50 (demand)................................  100 (demand; with       50 (demand)................................  100 (demand).
                                                                                    QLFT).
                                      2,000 (continuous flow)....................  Same as QNFT factor     50 (continuous flow).......................  1,000 (continuous flow).
                                                                                    (demand; sub-IDLH
                                                                                    value max.).
                                      2,000 (pressure demand)....................  Sub-IDLH (continuous    2,000 (pressure demand)....................  1,000 (pressure demand).
                                                                                    flow or pressure
                                                                                    demand; no escape
                                                                                    configuration).
                                                                                   10,000 max. (with
                                                                                    escape configuration).
Hood or helmet......................  2,000 (continuous flow)....................  Sub-IDLH (continuous    25 (continuous flow).......................  1,000 (continuous flow).
                                                                                    flow or pressure
                                                                                    demand; no escape
                                                                                    configuration).
                                                                                   10,000 max. (with
                                                                                    escape configuration).
Loose-fitting facepiece.............  ...........................................  ......................  25 (continuous flow).......................  25 (continuous flow).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 34102]]

    OSHA's proposed APFs for half-mask SARs. No WPF studies were 
available for half-mask SARs. Therefore, OSHA is proposing an APF of 10 
for this respirator class when used in the demand mode based on their 
analogous operational performance with negative pressure half-mask air-
purifying respirators tested during WPF and SWPF studies. In addition, 
the Agency proposes to give half-mask SARs that function in the 
continuous flow or pressure demand modes an APF of 50, consistent with 
the performance of half-mask PAPRs in WPF and SWPF studies (and 
operated at the same airflow rates). Additional support for the 
proposed APFs comes from the 1992 ANSI standard, which assigned an APF 
of 10 to half-mask airline SARs operated in the demand mode, and an APF 
of 50 when operated in the continuous flow or pressure demand mode. The 
1987 NIOSH RDL also gave half-mask demand SARs an APF of 10, but 
recommended an APF of 1,000 for these respirators when functioning in 
the pressure demand or other positive pressure modes.
    Regarding the recommended APF of 1,000, OSHA preliminarily finds 
that these respirators warrant the more conservative APF of 50 because 
of the possibility that negative pressure could develop inside the mask 
during tasks that stress the facepiece seal; moreover, in the absence 
of WPF and SWPF data for these respirators, the Agency believes that a 
conservative approach to setting this APF is appropriate.
    OSHA's proposed APFs for full facepiece SARs. No WPF or SWPF 
studies were available involving tight-fitting full facepiece SARs 
operated in the demand mode. Therefore, in the absence any such data, 
the Agency is assigning this respirator class an APF of 50 based on the 
analogous operational characteristics between these respirators and 
negative pressure air-purifying respirators when operated in the demand 
mode under WPF conditions. The proposed APF is the same as the APF 
recommended for this respirator class by the 1987 NIOSH RDL, and 
similar to the APF (i.e., 100) given to these respirators by the 1992 
ANSI standard. In choosing an APF of 50 instead of 100 for this class 
of respirators, the Agency believes that the paucity of WPF and SWPF 
studies warrants taking a conservative approach in this determination.
    While no WPF studies for full facepiece SARs operated in the 
pressure demand or other positive pressure modes were available, there 
was one SWPF study of this respirator class by Skaggs, Loibl, Carter, 
and Hyatt (Ex. 1-38-3). The study, performed at LANL, evaluated the 
respirators under different temperature and humidity conditions; the 
results of the study showed that these respirators had geometric mean 
protection factors ranging from 8,500 to 20,000. Therefore, the Agency 
is proposing an APF of 1,000 for full facepiece SARs used in the 
pressure demand or other positive pressure modes based on their 
performance in this study (i.e., that the likelihood is high that the 
geometric mean SWPFs would translate to fifth percentile WPF of 1,000. 
Further justification for the proposed APF comes from the similarity in 
operational characteristics (including the same minimum airflow rates) 
between these respirators and tight-fitting full facepiece continuous 
flow PAPRs, which are receiving a proposed APF of 1,000 in this 
rulemaking. (See the discussion of these PAPRs above).
    The proposed APF of 1,000 for full facepiece SARs operated in the 
pressure demand or other positive pressure modes also is consistent 
with the APFs of 1,000 assigned by the 1992 ANSI standard to these 
respirators when used in the continuous flow or pressure demand modes, 
and the APF of 2,000 recommended by the 1987 NIOSH RDL for pressure 
demand respirators in this class. Although the RDL gave an APF of 50 to 
these respirators in a continuous flow mode, the Agency believes that 
the SWPF study, as well as the WPF studies performed on analogous 
tight-fitting full facepiece continuous flow PAPRs, justify the 
proposed APF.
    OSHA's proposed APF for SARs with hoods or helmets. The Agency 
found a number of WPF studies on these respirators, including one by 
Johnston, Stokes, Mullins, and Rhoe (Ex. 1-64-36).
    These authors performed a WPF study on the 3M Whitecap continuous 
flow abrasive blasting helmet (equipped with an extended length shroud) 
used by four shipyard employees while sandblasting a barge. After 
performing several data analyses, the authors concluded that outside-
the-respirator samples with filter loadings at least 1,000 times 
greater than the mean blank value were most representative of the 
respirator's performance. Therefore, OSHA is using only statistics 
based on these samples for its APF determinations; these statistics 
indicate that the estimated fifth percentile protection factor is 1,038 
for these samples.
    Johnston, Stokes, Mullins, and Rhoe (Ex. 1-64-37) conducted a 
second WPF study on the 3M Whitecap II general purpose SAR with a 
helmet. In this study, the authors sampled six employees while they 
performed grinding operations in a foundry. The authors stated that 
``because of the relatively low sample loadings, the WPF numbers 
obtained significantly underestimate the performance capability of the 
respirator.'' Therefore, OSHA did not use the WPFs from this study in 
developing the proposed APF for this respirator class.
    Colton, Mullins, and Bidwell (Ex. 1-64-17) published a WPF study on 
foundry employees who used the 3M Snapcap continuous flow SAR with an 
abrasive blasting hood while exposed to silica during tear-down 
operations. The authors reported a fifth percentile protection factor 
over 1,000, which they noted was consistent with the APF of 1,000 
assigned to these respirators by the 1992 ANSI standard.
    In another WPF study, Nelson, Wheeler, and Mustard (Ex. 3-6) 
sampled aircraft assembly employees involved in sanding and primer 
spraying operations while using the 3M H-422 continuous flow SAR hood 
with both an outer and inner shroud. The authors reported that 14 of 
the 31 samples taken during primer spraying operations showed 
measurable concentrations of strontium (Sr) outside the facepiece 
(Co), but none of the samples showed any measurable 
concentration of Sr inside the facepiece (Ci). Based on 
these Co data, and using the lowest detectable limit for 
Ci, the authors concluded that ``the WPFs were greater than 
1,200 for all samples with a mass of Sr on the Co samples 
1,000 times the detection limit for the Ci samples.'' They 
stated further that their study supports the APF of 1,000 given to 
these respirators by the 1992 ANSI standard.
    In a WPF study conducted at Avondale shipyard, Kiefer, Trout, and 
Wallace (Ex. 2-1) sampled the total particulate exposures (i.e., small 
and large particle fractions combined) of employees involved in 
abrasive blasting operations while using the Bullard Type 88 CE 
(continuous flow) SAR abrasive blasting hood. The authors reported WPFs 
ranging from 2,817 to 10,000.
    OSHA identified four SWPF studies of this respirator class, all 
performed by LLNL or LANL for manufacturers of continuous flow SARs 
with abrasive blasting hoods or helmets. The geometric mean protection 
factors found for these respirators were 40,000 for the Bullard Model 
77 and 88 Type CE (continuous flow) SARs with an abrasive blasting hood 
(Ex. 1-157), and 100,000 for the Clemco Apollo 20 and 60 Type CE 
(continuous flow) SARs with an abrasive blasting hood (Ex. 3-7-3) and 
the 3M Whitecap Model W-8100 Type CE (continuous flow) SAR

[[Page 34103]]

with abrasive blasting helmet (Ex. 3-9-2). Based on the results of 
these studies, OSHA granted these respirators an interim APF of 1,000 
(Exs. 3-7-4, 3-8-4, 3-9-3).
    In the latest SWPF study, Johnson, Biermann, and Foote of LLNL and 
Cohen, Hecker, and Mattheis of ORC (Ex. 3-4) tested six models of 
continuous flow SARs with hoods or helmets as part of the ORC-LLNL SWPF 
Study. Five of these respirators had fifth percentile SWPFs ranging 
from 86,000 to over 250,000. However, the fifth percentile SWPFs for 
the sixth respirator (the North Model 85302 T) ranged from 13 to 18. 
The authors attributed the poor performance of this respirator to the 
absence of a ``tuck-in'' bib. When the manufacturer corrected this 
design problem by adding a tuck-in bib, the resulting model (designated 
the North Model 85302 TB) performed as well as most of the other 
respirators tested in the study.
    The following tables summarize the WPF and SWPF studies for tight-
fitting SARs with hoods or helmets.

----------------------------------------------------------------------------------------------------------------
                                                                                     Geometric
 WPF studies for SARS with hoods or helmets (by     Sample size   Geometric mean     standard     5th percentile
 name of authors and model of respirator tested)                                     deviation          WPF
----------------------------------------------------------------------------------------------------------------
Johnston et al. (Ex. 1-64-36) 3M W-8100 Whitecap              15           4,076             2.3           1,038
 II (abrasive blasting helmet with extended-
 length shroud).................................
Johnston et al. (Ex. 1-64-37):
    3M W-8000 Whitecap II (helmet)
        Study 1 (using 750 x field                  8           1,012             2.6             199
         blank with iron dust samples)..........
        Study 2 (using 30 x field                   8           1,417             3.0             224
         blank with silicon dust samples).......
Colton et al. (Ex. 1-64-17), 3M Snapcap W-3256                14          10,344             2.5           2,290
 (abrasive blasting hood).......................
Nelson et al. (Ex. 3-6), 3M H-422 (hood)........              31  ..............  ..............  1,0
                                                                                                              00
Kiefer et al. (Ex. 2-1), Bullard 88 Type Type CE              11  ..............  ..............  1,0
 (abrasive blasting hood).......................                                                              00
----------------------------------------------------------------------------------------------------------------


----------------------------------------------------------------------------------------------------------------
SWPF studies for SARs with hoods or helmets (by name                        Geometric mean/      5th percentile
     of authors and model of respirator tested)         Range of SWPFs        median SWPF             SWPF
----------------------------------------------------------------------------------------------------------------
Bullard-LLNL (Ex. 1-157) \1\, Bullard 77 and 88 Type  ..................    40,000  .................
 CE (abrasive blasting helmet)......................                                   (mean)
Clemco-LANL (Ex. 3-7-3) \2\, Apollo 20 and 60 Type    ..................   100,000  .................
 CE (abrasive blasting hood)........................                                   (mean)
3M-LANL (Ex. 3-9-2) \3\, 3M Whitecap Model W-8100     ..................   100,000  .................
 Type CE (abrasive blasting helmet).................                                   (mean)
ORC-LLNL SWPF Study (Ex. 3-4-2):
    3M Whitecap SAR (helmet with bib and chinstrap).  68,000-   250,000  250,00
                                                                 250,000             (median)                  0
    3M Snapcap (Tyvek hood with bib and chinstrap)..  13,000-   250,000    170,000-250,000
                                                                 250,000             (median)
    MSA Versa-hood (Tyvek hood).....................  9,700-2   250,000     86,000-114,000
                                                                  50,000             (median)
    North Model 85302 TB (Tyvek hood with bib)......  55,000-   250,000    150,000-240,000
                                                                 250,000             (median)
    North Model 85302 T (Tyvek hood, no bib)........  5-250,0         1,217 (mean)              13-18
                                                                      00
    Bullard CC20TIC (Tyvek hood and bib and           160,000-250,000  250,00
     chinstrap).....................................            >250,000             (median)                 0
----------------------------------------------------------------------------------------------------------------
\1\ Collected 288 samples (a panel of 4 respirator users x 12 exercises x 6 helmets).
\2\ Collected 264 samples (a panel of 4 respirator users x 11 exercises x 6 helmets).
\3\ Collected 132 samples (a panel of 4 respirator users x 11 exercises x 3 helmets).

    The Agency is proposing an APF of 1,000 for continuous flow SARs 
with hoods or helmets based on their performance in the WPF and SWPF 
studies. In each of the WPF studies [except the second WPF study by 
Johnston, Colton, Stokes, Mullins and Rhoe (Ex. 1-64-37)], these 
respirators attained a fifth percentile protection factor over 1,000. 
In addition, the large geometric mean protection factors found for 
these respirators provide substantial evidence for this proposed APF.
    The Agency qualified the proposed APF in footnote 4 of its proposed 
APF table. This footnote states that * * * only helmet/hood respirators 
that ensure the maintenance of a positive pressure inside the facepiece 
during use, consistent with performance at a level of protection of 
1000 or greater, receive an APF of 1000.'' and that ``[a]ll other 
helmet/hood respirators are treated as loose-fitting facepiece 
respirators and receive an APF of 25.'' Under this proposed 
requirement, an employer must select for employee use only continuous 
flow SARs with hoods or helmets that attained a protection factor of at 
least 1,000. While better performance has been associated with certain 
designs (e.g., double bibs, neck seals or dams, blouses, higher 
airflows), the presence of such design considerations are no guarantee 
of superior performance. In order to receive an APF of 1,000, it is 
contingent upon the respirator manufacturer to be able to demonstrate 
that their particular respirator meets the criteria specified in Table 
I of the proposed standard. This level of performance can best be 
demonstrated by performing a WPF or SWPF study. OSHA is proposing this 
requirement because previous WPF and SWPF testing conducted on these 
respirators shows that they do not always result in the requisite 
protection factor (Exs. 3-4, 3-5).
    Accordingly, researchers have recommended that such testing be 
performed to ensure that employees use only respirators from this class 
that provide them with the specified level of protection during 
exposure to hazardous substances. In this regard, while the respirator 
manufacturer most likely would perform the required testing, it would 
be incumbent on the employer to ensure that the respirators they 
selected for employee use received this testing.
    While the 1987 NIOSH RDL recommended an APF of 25 for continuous 
flow SARs with hoods or helmets, this recommendation is the result of 
combining these respirators into a single class with loose-fitting 
facepiece SARs, and giving the entire class the low APF (i.e., 25) 
assigned originally to loose-fitting facepiece respirators. However, 
the 1992 ANSI standard established a separate class for continuous flow 
SARs with hoods or helmets based on analogous operating

[[Page 34104]]

characteristics between these respirators and airline respirators at 
the same flow rates, with the new class having an APF of 1,000 (loose-
fitting facepiece SARs continued to receive an APF of 25). Accordingly, 
OSHA is proposing in this rulemaking to follow the procedure adopted by 
the 1992 ANSI standard and divide the two respirator types into 
separate classes, based principally on the WPF and SWPF performance of 
the continuous flow SARs with hoods or helmets.
    OSHA's proposed APF for loose-fitting facepiece SARs. No WPF or 
SWPF studies involving this respirator class were available. Therefore, 
using analogous operational characteristics between these respirators 
and loose-fitting facepiece PAPRs, OSHA is proposing to assign loose-
fitting facepiece SARs an APF of 25. In this regard, loose-fitting 
facepiece SARs, when evaluated under the NIOSH respirator-certification 
standards (42 CFR part 84), had the same minimum airflow rates found 
for loose-fitting facepiece PAPRs. Additional support for the proposed 
APF comes from the 1987 NIOSH RDL and the 1992 ANSI standard, both of 
which gave this respirator class an APF of 25.
6. Self-Contained Breathing Apparatuses (SCBAs)
    Historical development of APFs for SCBAs. As he did with full 
facepiece SARs used in the demand mode, Hyatt in 1976 assigned a 
protection factor of 50 to a full facepiece SCBA operated in this mode. 
Based on results from a panel of 31 respirator users tested at LANL, he 
gave full facepiece SCBAs used in the pressure demand mode an APF of 
10,000+ (Ex. 2). The 1980 ANSI standard listed half-mask and full 
facepiece SCBAs operated in the demand mode as having APFs of 10 and 
100, respectively, when qualitatively fit tested; when quantitatively 
fit tested, the APFs for half-mask or full facepiece SCBAs functioning 
in the demand mode were the protection factors obtained during fit 
testing, with this APF limited to the sub-IDLH value. Full facepiece 
SCBAs used in the pressure demand mode received an APF of 10,000+. The 
1987 NIOSH RDL recommended that half-mask and full facepiece SCBAs 
operated in the demand mode receive APFs of 10 and 50, respectively, 
and that the APF for full facepiece SCBAs operated in the pressure 
demand or other positive pressure mode be 10,000.
    The committee responsible for the 1992 ANSI standard could not 
reach a consensus on an APF for full facepiece pressure demand SCBAs. 
As noted in footnote 4 of the APF table in this ANSI standard, 
available WPF and SWPF studies reported that, in some individual cases, 
the respirators did not achieve an APF of 10,000 (Ex. 1-50). 
Nevertheless, the committee found that a maximum APF of 10,000 was 
appropriate when employers used the respirators for emergency planning 
purposes and could estimate levels of hazardous substances in the 
workplace.
    Two newly developed respirators equipped with hoods, Draeger's Air 
Boss Guardian and Survivair's Puma, have operational characteristics 
similar to SCBAs. The facepiece of the Draeger respirator consists of a 
hood with an inner nose cup and a seal at the neck; an air cylinder 
supplies air to the facepiece. NIOSH reviewed this respirator in 
accordance with its certification requirements specified at 42 CFR part 
84, and in January 2001 certified the respirator as a tight-fitting 
full facepiece demand SCBA, with the cylinder having a 30-minute 
service life; NIOSH also approved the respirator for use in entering 
and escaping from hazardous atmospheres. In a May 16, 2001 letter to 
OSHA's Directorate of Compliance Programs (Ex. 7-1), Mr. Richard 
Metzler of NIOSH justified the classification of the Draeger respirator 
as an SCBA on the basis that the neck seal, which is integral to the 
facepiece, forms a gas-tight or dust-tight fit with the face, 
consistent with the definition of a tight-fitting facepiece specified 
by 42 CFR 84.2(k). This letter also noted that the fit testing 
procedures used for full facepiece demand SCBAs apply to the Draeger 
SCBA, and that, as a full facepiece demand SCBA, NIOSH recommended that 
the respirator receive an APF of 50 in accordance with its 1987 RDL.
    NIOSH subsequently reviewed the Survivair Puma respirator, which 
has a tight-fitting hood supplied by an air cylinder; and certified the 
respirator as a pressure demand SCBA with a tight-fitting facepiece. As 
part of the certification process, NIOSH specified that fit testing 
required of SCBAs would apply to this respirator. However, Steve 
Weinstein of Survivair (Ex. 7-2) stated that the hood totally 
encapsulates the respirator user's hair, making quantitative fit 
testing (e.g, with a Portacount) impossible; in such cases, the fit 
testing instrumentation treats dander and other material shed by the 
hair as particulates from outside the respirator, causing the fit 
factor to be artificially low. However, qualitative fit testing with 
the hood is possible because Survivair provides an adapter and P100 
filters for this purpose; such fit testing meets the fit-testing 
requirements for tight-fitting SCBAs specified in paragraph (f)(8) of 
OSHA's Respiratory Protection Standard.
    The table below provides a summary of APFs given to the half-mask 
and full facepiece SCBAs from Hyatt's 1976 studies at LLNL to the 1992 
ANSI standard.

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                 APFs
               SCBAs                ------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                     LANL (1976)                    1980 ANSI standard                 NIOSH RDL (1987)                           1992 ANSI standard
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Tight-fitting half-mask............  10 (demand)................................  10 (demand; with QLFT)  10 (demand)...............................
                                                                                   Same as QNFT factor
                                                                                   (demand; sub-IDLH
                                                                                   value max.).
Tight-fitting full facepiece.......  50 (demand)................................  100 (demand; with       50 (demand)...............................
                                                                                   QLFT) Same as QNFT
                                                                                   factor (demand; sub-
                                                                                   IDLH value max.).
Tight-fitting full facepiece.......  10,000 (pressure demand)...................  10,000+ (pressure       10,000 (pressure demand)..................  10,000 max. (emergency planning purposes
                                                                                   demand).                                                            only).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    OSHA's proposed APFs for SCBAs. No WPF or SWPF studies for tight-
fitting half-mask SCBAs and tight-fitting full facepiece SCBAs operated 
in the demand mode were available. In the only WPF study conducted on 
full

[[Page 34105]]

facepiece positive pressure SCBAs, Campbell, Noonan, Merinar, and 
Stobbe of NIOSH assessed the performance of two different models of 
full facepiece pressure demand SCBAs that met the NFPA 1981 airflow 
requirements for respirators used by firefighters (Ex. 1-64-7). While 
the authors could not determine WPFs for these respirators because 
contaminant levels measured inside the facepiece were too low, pressure 
measurements taken inside the facepiece proved more useful. These 
measurements showed that four of the 57 firefighters experienced one or 
more negative-pressure incursions inside the facepiece while performing 
firefighting tasks. After analyzing the data for these firefighters 
using two different methods, the authors estimated that the overall 
protection factor exceeded 10,000.
    In the first of two SWPF studies performed on full facepiece SCBAs 
used in the pressure demand mode, McGee and Oestenstad (Ex. 1-64-86) 
determined the protection afforded to members of a respirator test 
panel consisting of 23 men wearing the Biopack 60 closed circuit SCBA 
(Ex. 1-64-86). Three members of the panel had protection factors of 
4,889, 7,038, and 18,900, with the remaining members having protection 
factors over 20,000. In the second study, Johnson, da Roza, and 
McCormack of LLNL (Ex. 1-64-98) tested the Survivair Mark 2 SCBA that 
met NFPA 1981 airflow requirements; during testing, a panel of 27 
respirator users exercised on a treadmill at 80% of their cardiac 
reserve capacity. Although the authors found negative-pressure 
incursions inside the facepiece at high work rates, they concluded that 
the respirator ``provided [a minimum] average fit factor of 10,000 [for 
any single subject], with no single subject having a fit factor less 
than 5,000 at a high work rate.''
    The tables below summarize the results of the WPF and SWPF studies 
performed on full facepiece pressure demand SCBAs.

----------------------------------------------------------------------------------------------------------------
  WPF studies for tight-fitting full facepiece                                       Geometric
 pressure demand SCBAs  (by name of authors and     Sample size   Geometric mean     standard     5th percentile
           model of respirator tested)                                               deviation          WPF
----------------------------------------------------------------------------------------------------------------
Campbell et al. (Ex. 1-64-7), Unspecified model               57  ..............  ..............          10,000
 (with NFPA-compliant airflow)..................                                                     (estimated)
----------------------------------------------------------------------------------------------------------------


----------------------------------------------------------------------------------------------------------------
  SWPF studies for tight-fitting full facepiece                                      Geometric
 pressure demand SCBAs  (by name of authors and     Sample size   Geometric mean     standard     5th percentile
           model of respirator tested)                                               deviation          WPF
----------------------------------------------------------------------------------------------------------------
McGee and Oestenstad (Ex. 1-64-86), Biopack 60                23          20,000  ..............  ..............
 (closed circuit)...............................
Johnson et al. (Ex. 1-64-98), Survivair Mark 2                27          29,000            1.63  ..............
 (with NFPA-compliant airflow)..................
----------------------------------------------------------------------------------------------------------------

    OSHA is proposing APFs of 10 and 50, respectively, for tight-
fitting half-mask SCBAs and tight-fitting full facepiece SCBAs operated 
in the demand mode. In the absence of any WPF and SWPF studies on these 
respirators, the Agency derived the proposed APFs based on analogous 
operational characteristics between these respirators and half-mask 
facepiece and full facepiece air-purifying respirators for which WPF 
and SWPF studies (described previously) are available. In addition, the 
proposed APFs are consistent with the APFs recommended by the 1987 
NIOSH RDL for these respirators. (Note that the 192 ANSI standard did 
not assign APFs for these respirator classes.)
    For tight-fitting full facepiece SCBAs used in the pressure demand 
or other positive pressure modes, OSHA is proposing an APF of 10,000, 
which is consistent with the 1987 NIOSH RDL and the 1992 ANSI standard. 
Empirical support for the proposed APF comes from the WPF study 
conducted by Campbell, Noonan, Merinar, and Stobbe (Ex. 1-64-7). This 
study showed that individual protection factors for these respirators, 
when operating at NFPA-compliant airflows, far exceed 10,000; however, 
four respirator users experienced momentary negative-pressure spikes 
inside the facepiece, indicating possible leakage of ambient 
contamination into the facepiece, and the breathing zone of the user, 
under some workplace conditions.
    The two SWPF studies also provide support for the proposed APF, 
although several individual protection factors fell below 10,000 in the 
two studies, and the Johnson, da Roza, and McCormack study (Ex. 1-64-
98) found negative-pressure incursions inside the facepiece during high 
exercise rates. Since the WPF and SWPF studies indicate that these 
respirators fail to provide the designated level of protection under 
some conditions, OSHA states in footnote 5 of its proposed APF table 
that ``[w]hen employers can estimate hazardous concentrations for 
emergency planning purposes, they must use a maximum assigned 
protection factor no higher than 10,000.'' Therefore, this proposed 
provision limits use of tight-fitting full facepiece positive pressure 
SCBAs to conditions for which an emergency-response plan exists and the 
employer can estimate the concentration of the hazardous substance in 
those conditions; in addition, the employer must restrict respirator 
use to conditions in which the required level of employee protection is 
at or below an APF of 10,000.
    In proposing to limit use of tight-fitting full facepiece positive 
pressure SCBAs to planned emergency conditions only, OSHA acknowledges 
that while these respirators are among the most protective respirators 
available, the existing WPF and SWPF data demonstrate that they do not 
consistently provide employees with a protection level of 10,000 under 
some exposure conditions. Therefore, the Agency is proposing that 
employers not use these respirators routinely for protecting employees 
against workplace exposures requiring an APF above 1,000, but instead 
limit their use to non-routine (i.e., emergency) conditions that 
require high levels of respirator protection. In this regard, the 
Agency believes that few, if any, routine exposure conditions in the 
workplace require protection above an APF of 1,000; consequently, the 
proposed restriction would have minimal effect on routine respirator 
use.\11\
---------------------------------------------------------------------------

    \11\ In preparing the risk analysis for the final Respiratory 
Protection Standard, OSHA reviewed data in its Integrated Management 
Information System for the years 1992 to 1996 to determine 
overexposure rates to the hazardous substances listed in Table Z 
(``Limits for air contaminants'') of 29 CFR 1910.1000. The Agency 
found that less than 0.01% of the exposures to these substances 
exceeded an APF of 1,000.

---------------------------------------------------------------------------

[[Page 34106]]

    To use full facepiece positive pressure SCBAs under emergency 
exposure conditions, the proposal specifies that employers must develop 
an emergency plan (which several substance specific standards already 
require), and provide an estimate of the concentration levels likely to 
result under the emergency conditions. Emergency plans would limit 
employee exposure to the hazardous conditions by informing them in 
advance of the specific tasks they are to perform, while estimating 
concentration levels of the hazardous substance would increase the 
likelihood that their exposures to the substance will remain within the 
APF assigned to the respirator. In addition, OSHA's proposal to limit 
use of these respirators to emergency conditions is similar to the 
restriction placed on them in footnote 4 of the APF table published in 
---------------------------------------------------------------------------
the 1992 ANSI standard; this restriction reads, in part:

    [A] definitive assigned protection factor could not be listed 
for positive-pressure SCBAs. For emergency planning purposes where 
hazardous concentrations can be estimated, an assigned protection 
factor of no higher than 10,000 should be used. (Ex. 1-50)

For the class of respirators designated as pressure demand SCBAs with 
tight-fitting hoods or helmets, including the Survivair Puma, OSHA is 
proposing an APF of 10,000 maximum. The basis for this proposed APF are 
the analogous operational characteristics between these respirators and 
tight-fitting full facepiece pressure demand SCBAs. Accordingly, the 
Agency proposes to limit use of demand SCBAs with tight-fitting hoods 
or helmets to emergency planning purposes, similar to the restriction 
it is placing on tight-fitting full facepiece pressure demand SCBAs.
Paragraph (d)(3)(i)(B)--MUC Provisions
    These proposed requirements consist of four separate paragraphs 
[(d)(3)(i)(B)(1) through (d)(3)(i)(B)(4)]. Paragraph (d)(3)(i)(B)(1), 
which proposes requirements on the use and application of MUCs, reads, 
``The employer must select a respirator for employee use that maintains 
the employee's exposure to the hazardous substance, when measured 
outside the respirator, at or below the MUC.'' This proposed paragraph 
requires employers to select respirators for employee protection that 
are appropriate to the ambient levels of the hazardous substance found 
in the workplace, i.e., that the ambient level of the hazardous 
substance must never exceed the conditions specified by the MUC, which 
is the exposure limit specified for the hazardous substance multiplied 
by the respirator's APF. Accordingly, the proposed requirement ensures 
that employers maintain employees' direct exposure to hazardous 
substances (i.e., inside the respirator) within levels specified by 
OSHA's Z tables and substance-specific standards, and where OSHA has no 
standards, within consensus standards levels. Therefore, this provision 
would not only provide employee protection consistent with prevailing 
industrial-hygiene practice, but with existing regulatory and statutory 
requirements as well.
    The single note in the proposed MUC provisions follows paragraph 
(d)(3)(i)(B)(1). This note reads that ``MUCs are effective only when 
the employer has a continuing, effective respiratory protection program 
as specified by 29 CFR 1910.134, including training, fit testing, 
maintenance and use requirements.'' This provision implies that MUCs 
are dependent on the APFs of the respirators selected by employers to 
protect employees against airborne contaminants. In this regard, the 
Agency determined the APF for a respirator or class of respirators 
based on studies that assessed the respirator under conditions that met 
or exceeded the program requirements of its Respiratory Protection 
Standard at 29 CFR 1910.134. These studies ensured that the study 
participants who used the respirators received thorough respirator 
training and fit testing, and used the respirators correctly; also, 
employers (or research staff in the case of SWPF studies) maintained 
the respirators in proper operating condition. Consequently, the APF 
used in calculating a MUC is valid for this purpose only if employers 
implement a continuing, effective, and comprehensive respiratory-
protection program as required by OSHA's Respiratory Protection 
Standard. When employers do not meet the conditions specified in this 
note, they may not use the respirator's APF in determining the MUC.
    The next MUC provision, proposed paragraph (d)(3)(i)(B)(2), states 
that ``[e]mployers must comply with the respirator manufacturer's MUC 
for a hazardous substance when the manufacturer's MUC is lower than the 
calculated MUC specified by this standard.'' While OSHA believes that a 
MUC calculated according to the proposed MUC definition normally would 
provide adequate employee protection, it defers to respirator 
manufacturers when they recommend a lower MUC for their respirators 
under specific hazardous-substance conditions. Respirator manufacturers 
warrant such deference because they are most familiar with the 
functional limitations of their respirators when exposed to airborne 
concentrations of hazardous substances. Also, manufacturer's may base 
their recommended MUCs on unpublished WPF or SWPF studies; such 
studies, when conducted properly, would increase the validity of their 
recommendations. As with a MUC determined using OSHA's proposed 
calculation method, the Agency believes that the protection afforded to 
employees by a respirator manufacturer's MUC depends on the employer's 
full compliance with the comprehensive respiratory-protection program 
specified by OSHA's Respiratory Protection Standard.
    The Agency would not defer to respirator manufacturers who 
recommend higher MUCs than an employer would obtain using the proposed 
calculation method because such results would not be consistent with 
the maximum ambient level of a hazardous substance in which employees 
can use the respirators, i.e., the maximum ambient level of a hazardous 
substance would exceed the level determined from the known exposure 
limit for the hazardous substance and the protection of the APFs 
determined by this proposed rulemaking. Under these conditions, the 
respirator manufacturer would be basing the recommendation on an 
invalid application of the known exposure limit or the APF (or both); 
therefore, such an invalid application would cause employers to select 
respirators that are incapable of protecting employees from the ambient 
level of a hazardous substance, resulting in serious health impairments 
to their employees.
    Paragraph (d)(3)(i)(B)(3) of the proposed MUC provisions states, 
``Employers must not apply MUCs to conditions that are immediately 
dangerous to life or health (IDLH); instead, they must use respirators 
listed for IDLH conditions in paragraph (d)(2) of this standard.'' 
Accordingly, employers could not use the proposed MUC calculation 
method (or a respirator manufacturer's MUC) to select a respirator for 
employees who are entering an IDLH atmosphere. OSHA found support for 
these proposed requirements in comments cited in the preamble to the 
final Respiratory Protection Standard. These comments noted that 
employers should not use MUCs to select respirators for employees 
exposed to IDLH

[[Page 34107]]

atmospheres (Ex. 1-54-381), or stated that employees should not use 
air-purifying respirators, including powered air-purifying respirators, 
while exposed to IDLH or oxygen-deficient atmospheres (Ex. 1-54-38); 
these commenters believed that the MUCs (and the APFs on which they are 
based) would not protect employees under these extremely hazardous 
exposure conditions.
    For employees exposed to IDLH conditions, employers must select a 
respirator according to the requirements specified by paragraph (d)(2) 
of OSHA's Respiratory Protection Standard. Paragraph (d)(2) requires 
employers to select a full facepiece, pressure demand SCBA certified by 
NIOSH to have a service life of at least 30 minutes, or a combination 
full facepiece, pressure demand, supplied-air respirator with an 
auxiliary self-contained air supply, for IDLH exposures. In the 
preamble to the final Respiratory Protection Standard, the Agency 
justified selecting these respirators as follows:

    In [IDLH] atmospheres there is no tolerance for respirator 
failure. This record supported OSHA's preamble statement that IDLH 
atmospheres ``require the most protective types of respirators for 
workers.

(59 FR 58896.) Commenters and respirator authorities, including NIOSH, 
ANSI, and both labor and management, agree that, for IDLH atmospheres, 
the most highly protective respirators, with escape capability, should 
be required (63 FR 1201).
    The last proposed MUC provision, paragraph (d)(3)(i)(B)(4), 
requires that ``[w]hen the calculated MUC exceeds another limiting 
factor such as the IDLH level for a hazardous substance, the lower 
explosive limit (LEL), or the performance limits of the cartridge or 
canister, then employers must set the maximum MUC at that lower 
limit.'' As with manufacturers' MUCs, these limiting factors would take 
precedence over the calculated MUC when they result in lower employee 
exposures to the hazardous substances than the calculated MUC; 
consequently, employees would receive increased protection against 
these hazardous substances.
    This proposed paragraph cites several performance limits (i.e., the 
IDLH or LEL for a hazardous substance, or the service life of a 
cartridge or canister) as examples of limiting factors. In this regard, 
OSHA is including these limiting factors as examples only; other 
limiting factors specified in a variety of OSHA standards, or used by 
employers to meet their obligation to provide a safe and healthful 
workplace, also would be applicable to this proposed requirement. In 
addition, commenters cited in the preamble to the final Respiratory 
Protection Standard believed that employers should not rely on MUCs 
determined using the proposed calculation method to estimate the 
service life of cartridges and canisters (Exs. 1-54-153, 1-54-165A, 1-
54-222, 1-54-381).

B. Superseding the Respirator-Selection Provisions of Substance-
Specific Standards in Parts 1910, 1915, and 1926

1. Introduction
    The substance-specific standards in 29 CFR parts 1910, 1915, and 
1926 specify numerous requirements for regulating employee exposure to 
toxic substances, including APFs for respirator selection. Under this 
proposed rulemaking, OSHA would revise the provisions in its substance-
specific standards that regulate APFs (except the APF requirements for 
the 1,3-Butadiene Standard at 29 CFR 1910.1051). These proposed 
revisions would remove the APF tables from these standards, as well as 
any references to these tables, and would replace them with a reference 
to the APF and MUC provisions specified in proposed paragraphs 
(d)(3)(i)(A) and (d)(3)(i)(B) of the Respiratory Protection Standard at 
29 CFR 1910.134. The Agency believes that the proposed revisions would 
simplify compliance for employers by removing many inconsistencies in 
APF requirements across its substance-specific standards; therefore, 
the proposed revisions would enhance consolidation and uniformity of 
these requirements. Accordingly, the purpose of revising the APF 
provisions of OSHA's substance-specific standards is to conform these 
standards, to the extent possible, to each other and to general APF and 
MUC requirements specified by 29 CFR 1910.134.
    The proposed revisions would improve the substance-specific 
standards because the Agency developed these proposed APF requirements 
after careful review and analysis of the available scientific data and 
the most recent consensus standards (i.e., the APF provisions in the 
NIOSH RDL and the ANSI Z88.2-1992 respiratory protection standard). In 
this regard, the Agency preliminarily finds that the proposed APFs are 
a significant improvement over the existing NIOSH and ANSI APFs because 
it developed them based on the latest WPF and SWPF studies, and used 
advanced statistical methods to identify common and unique variance 
among respirator classes. Therefore, the proposed APFs represent the 
best data and analytic techniques available, thereby lending a high 
degree of reliability and validity to the results. Accordingly, the 
proposed APFs will provide employers with confidence that their 
employees will receive the level of protection from airborne 
contaminants signified by these APFs. In addition, applying the 
proposed APFs to the substance-specific standards is consistent with 
OSHA's goal of bringing uniformity to its respiratory-protection 
requirements. Moreover, protection for workers is increased since the 
proposed APFs will provide equivalent or increased protection compared 
to the ANSI Z88.2-1992 standard, and incorporates the use of APFs into 
the employer's respiratory protection program. The Agency believes that 
superseding the APF requirements of its existing substance-specific 
standards would result in regulatory consistency, which would improve 
employer compliance with these provisions, reduce the compliance burden 
on the regulated community, and, consequently, further enhance the 
protection afforded to employees who use respirators.
    In the final rulemaking for its Respiratory Protection Standard, 
OSHA noted that the revised standard was to ``serve as a `building 
block' standard with respect to future standards that may contain 
respiratory protection requirements.'' (See 63 FR 1265, 1998.) In this 
regard, the Agency believes that, to the extent possible, future 
substance-specific standards should refer to provisions of the final 
Respiratory Protection Standard instead of containing their own 
respirator requirements, including the generic APF and MUC provisions 
specified in this proposed rulemaking. However, on occasion a 
substance-specific standard may have respirator-selection requirements 
that supplement or supplant the generic APF and MUC provisions (e.g., 
organic-vapor cartridge and canister procedures, prohibiting use of 
filtering facepieces or half-mask respirators) that are necessary for 
ensuring adequate employee protection against the toxic substance 
regulated by the standard. Accordingly, the Agency is retaining a 
number of existing respirator-selection provisions that are unique to 
the substance-specific standards; the following paragraphs describe 
these provisions, and provide OSHA's rationale for retaining them.

[[Page 34108]]

2. Retaining the Respirator-Selection Provisions of the 1,3-Butadiene 
Standard
    As noted earlier in this section, OSHA is not proposing to revise 
the respirator-selection provisions of the 1,3-Butadiene Standard (``BD 
Standard''). Therefore, the APFs located in Table 1 (``Minimum 
Requirements for Respiratory Protection for Airborne BD'') of the BD 
Standard would remain as currently published in paragraph (h)(3) 
(``Respirator selection'') of 29 CFR 1910.1051.
    The BD Standard requires that employers use respirators during work 
operations when engineering and work-practice controls ``are not yet 
sufficient to reduce employee [BD] exposures to or below the 
[permissible exposure limits]'' [see 29 CFR 1910.1051(h)(1)(iii)]. 
Employers must select these respirators based on the APFs listed in 
Table 1 of the BD Standard; in addition, they must equip air-purifying 
respirators with organic-vapor cartridges or canisters.
    OSHA adopted the APFs in Table 1 from the Respirator Decision Logic 
developed by the National Institute for Occupational Safety and Health 
(NIOSH), even though a negotiated agreement between manufacturers who 
use BD and the unions representing their employees recommended the more 
permissive ANSI Z88-1992 APFs.
    In the preamble to the final BD Standard, the Agency noted that its 
``decision to rely on the more protective NIOSH APFs is based on 
evidence showing that organic-vapor cartridges and canisters have 
limited capacity for adsorbing BD and may have too short a service life 
when used in environments containing greater than 50 ppm BD.'' (See 61 
FR 56816.) While developing the final BD Standard, OSHA reviewed the 
breakthrough test data that were available for organic-vapor cartridges 
and canisters challenged against BD (and summarized in Table X-1 of the 
preamble to the final BD Standard; see 61 FR 56817). Based on this 
review, the Agency concluded:

    Allowing for a reasonable margin of protection, and given that 
test data were available only for a few makes of cartridges and 
canisters, OSHA believes that air-purifying devices should not be 
used for protection against BD present in concentrations greater 
than 50 ppm, or 50 times the 1 ppm PEL. Thus, OSHA finds that the 
ANSI APFs of 100 for full facepiece, air-purifying respirators and 
1,000 for PAPRs equipped with tight-fitting facepieces are 
inappropriate for selecting respirators for BD.

In summary, test data cited by the Agency in the final BD Standard 
demonstrate short breakthrough times for BD concentrations above 50 
ppm. Accordingly, these short breakthrough times justified limiting to 
50 ppm the upper limit at which employees can use air-purifying 
respirators for protection against BD exposures. From the Agency's 
analysis of these data, OSHA also developed change schedules for 
cartridges and canisters that are unique for BD exposures (see Table 1 
of the BD Standard). Additionally, these conclusions still are likely 
to be valid because OSHA reviewed the test data only six years ago 
(i.e., 1996). Therefore, the Agency is proposing to retain the 
conservative NIOSH APFs as necessary to protect employees from BD 
exposures. Nevertheless, OSHA is asking employers and employees who are 
subject to the provisions of the existing BD Standard to provide 
additional information that supports retaining the existing APFs or 
adopting the generic APFs specified under this proposed rulemaking (See 
Section VII , Issues, of this preamble).
3. Retaining the Respirator-Selection Provisions in Other Substance-
Specific Standards
    While OSHA is proposing to retain the existing BD Standard in its 
entirety, it also is proposing to retain a number of respirator-
selection provisions in other substance-specific standards as well. The 
respirator-selection requirements proposed for retention often provide 
protection against a hazardous characteristic or condition that is 
unique to the regulated substance. Additionally, OSHA believes that 
retaining these requirements in their present form (except for plain-
language revisions, as appropriate) would not increase existing 
employer burden because they already must comply with these 
requirements; consequently, retaining these provisions will maintain 
the level of respirator protection currently afforded to employees. The 
following sections describe the most important provisions that the 
Agency is proposing to retain.\12\
---------------------------------------------------------------------------

    \12\ Most of the provisions described in these sections are in, 
or are footnotes to, the respirator-selection tables proposed for 
removal from the substance-specific standards. These sections also 
describe several other respirator-selection provisions that are not 
part of these tables, but which OSHA is retaining and which may be 
of interest to the regulated community. If this proposal does not 
specifically identify or describe a respirator-selection provision 
for removal or revision, then OSHA is retaining that provision in 
its existing form. The Agency believes that retaining these 
provisions does not increase the regulatory burden of employers 
because they must currently comply with them.
---------------------------------------------------------------------------

    [sbull] Lines 13-17 \13\ and 21-21 under ``Required apparatus'' in 
the undesignated table of 29 CFR 1910.1017 (Vinyl Chloride (VC) 
Standard); and footnote 1 to Table 1 of 29 CFR 1910.1028 (Benzene 
Standard). These provisions specify a minimum service life for 
cartridges and canisters used to protect employees during exposure to 
these substances. In the VC Standard, employers must provide organic-
vapor cartridges or canisters with a service life of at least one hour 
at VC concentrations up to 10 ppm when using chemical-cartridge 
respirators. These cartridges and canisters must have a service life of 
at least four hours at VC concentrations up to 25 ppm when using a 
canister with a powered air-purifying respirator that has a hood, 
helmet, half-mask, or full facepiece; the four-hour service-life 
requirement also applies when an employee uses a gas mask, but in this 
case, the employee must use a front-or back-mounted canister. According 
to the Benzene Standard, employers must ensure that canisters used with 
non-powered air-purifying respirators have a minimum service life of 
four hours when tested at 150 ppm benzene at a flow rate of 64 liters 
per minute (Lpm), a temperature of 25[deg] C, and a relative humidity 
of 85%; testing for canisters used with tight-fitting and loose-fitting 
powered air-purifying respirators must be at flow rates of 115 Lpm and 
170 Lpm, respectively.
---------------------------------------------------------------------------

    \13\ Only lines with written text were counted in determining 
the number of lines; blank lines that occurred before a written line 
were ignored for counting purposes.
---------------------------------------------------------------------------

    The Agency believes that these minimum service-life specifications 
ensure that employers use the designated respirators at appropriate 
concentration levels of the regulated substances. Accordingly, OSHA is 
proposing to retain these specifications to provide employees with a 
minimum level of cartridge and canister endurance when they use the 
designated respirators at these concentrations. While retaining these 
specifications may limit employers' flexibility in adopting change 
schedules, the Agency considers this limitation warranted in view of 
the properties of the substance that require greater protection or a 
higher level of protection for employees. Moreover, retaining these 
specifications adds no regulatory burden on employers because they must 
use the specifications under the existing standards.
    [sbull] Paragraphs (h)(3)(ii), and lines 6, 7, 10, and 11 under 
``Required respirator'' in Table II of 29 CFR 1910.1018 (Inorganic 
Arsenic Standard); lines 1-4

[[Page 34109]]

under ``Respirator type'' in Table 1 of 29 CFR 1910.1028 (Benzene 
Standard); line 1 under ``Minimum required respirator'' in Table 1 of 
29 CFR 1910.1047 (Ethylene Oxide Standard); lines 1-4 under ``Minimum 
respirator required'' in Table 1 of 29 CFR 1910.1048 (Formaldehyde 
Standard); and lines 1-3 and 8, and footnote 2, under ``Respirator 
type'' in Table 1 of 29 CFR 1910.1050 and 1926.60 (Methylenedianiline 
(MDA) Standards).
    These paragraphs identify the types of cartridges and canisters 
employers must select under specific respirator-use conditions. The 
Inorganic Arsenic Standard requires employers to provide employees 
with: Air-purifying respirators that have a combination high-efficiency 
particulate air (HEPA) filter with an appropriate gas-sorbent cartridge 
or canister when their exposure exceeds the permissible exposure level 
for inorganic arsenic, and their exposure also exceeds the relevant 
limit for other gases; front- or back-mounted gas masks equipped with 
HEPA filters and acid-gas canisters or any full facepiece supplied-air 
respirators when the inorganic arsenic concentration is at or below 500 
[mu]g/m3; and half-mask air-purifying respirators equipped 
with HEPA filters and acid-gas cartridges when the inorganic arsenic 
concentration is at or below 100 [mu]g/m3. The Benzene 
Standard specifies that employers must use an organic-vapor cartridge 
or canister with air-purifying respirators, and a chin-style canister 
with full facepiece gas masks. The Ethylene Oxide Standard states that 
employers are to equip air-purifying, full facepiece respirators with 
front- or back-mounted canisters approved for protection against 
ethylene oxide, while the same respirators under the Formaldehyde 
Standard must use a cartridge or canister approved for protection 
against formaldehyde. The MDA Standard requires that employers provide 
air-purifying respirators with a combination HEPA filter and organic-
vapor cartridge or canister when MDA is in liquid form or is part of a 
heated process.
    [sbull] Line 1 under ``Required respirator'' in Table 1 of 29 CFR 
1910.1001, 1915.1001, and 1926.1101(Asbestos Standards); line 6 under 
``Required respirator'' in Table I of 29 CFR 1910.1029 (Coke Oven 
Emissions Standard); and line 2 under ``Required respirator'' in Table 
I of 29 CFR 1910.1043 (Cotton Dust Standard).
    These provisions prohibit the use of disposable respirators 
(single-use respirators in the Coke Oven Emissions Standard) to protect 
employees against these toxic substances; the Cotton Dust Standard 
prohibits their use at exposures greater than five times the 
permissible exposure level (PEL). However, the Agency does not define 
the terms ``disposable respirator'' or ``single-use respirator'' in any 
of its standards, including its Respiratory Protection Standard at 29 
CFR 1910.134; therefore, to update these requirements, the Agency is 
proposing to replace these terms with ``filtering facepiece,'' which it 
defines in paragraph (b) of 29 CFR 1910.134. OSHA believes this 
revision will not only make these provisions consistent with its new 
Respiratory Protection Standard, but will prevent employers from using 
respirators not designed with the high-efficiency particulate filters 
necessary to capture respirable asbestos fibers (see 51 FR 22718) and 
coke oven emissions (see 41 FR 46773-46774), and, in the case of cotton 
dust, to provide protection at exposure levels higher than five times 
the PEL (see 50 FR 51153-51154).
    [sbull] Paragraphs (h)(2)(iv) of 29 CFR 1915.1001 and (h)(3)(iii) 
of 29 CFR 1926.1101 (Asbestos Standards) also prohibit employers from 
selecting disposable respirators for employees who conduct specific 
types of Class II and III asbestos work. Consistent with the 
explanation and rationale provided in the previous section, OSHA is 
proposing to revise the term ``disposable respirator'' to ``filtering 
facepiece'' in these standards. The Agency also is proposing to revise 
these paragraphs, as well as paragraph (h)(2)(v) of 29 CFR 1915.1001 
and (h)(3)(iv) of 29 CFR 1926.1101 (which address respirator selection 
for conducting Class I asbestos work in regulated areas), into plain 
language to clarify the multifaceted requirements specified by these 
paragraphs. By improving employer understanding of the respirator-
selection requirements, OSHA believes that the revisions proposed for 
these paragraphs would enhance employee protection without increasing 
employers' regulatory burden.
    [sbull] Lines 2, 3, and 4 under ``Required respirator'' in Table 1 
of 29 CFR 1910.1001, 1915.1001, and 1926.1101(Asbestos Standards); 
lines 5-6, 8, and 11 under ``Required respirator'' in Table I , and 
lines 6 and 10 under ``Required respirator'' in Table II, of 29 CFR 
1910.1018 (Inorganic Arsenic Standard); lines 1, 2, and 3 under 
``Required respirator'' in Table II of 29 CFR 1910.1025 (Lead 
Standard); lines 1, 3, 5, 6, and 10 under ``Required respirator type'' 
in Table 2 of 29 CFR 1910.1027 (Cadmium Standard); lines 1, 3, 4, and 5 
under ``Required respirator'' in Table I of 29 CFR 1910.1043 (Cotton 
Dust Standard); lines 1, 2, 3, and 8 under ``Respirator type'' in Table 
1 of 29 CFR 1910.1050 and 1926.60 (Methylenedianiline Standard); lines 
1, 3-4, 7, and 8 under ``Required respirator'' in Table 1 of 29 CFR 
1926.62 (Lead Standard); and lines 1, 3, 6, 8, and 11 under ``Required 
respirator type'' in Table 1 of 29 CFR 1926.1127 (Cadmium Standard).
    Under these provisions, employers must equip air-purifying 
(including powered air-purifying) respirators with high-efficiency 
particulate air (HEPA) filters, high-efficiency and high-efficiency 
particulate filters (defined as a filter that is at least 99.97% 
efficient against mono-dispersed particles of 0.3 micrometers in 
diameter or larger), and particulate filters (for the Cotton Dust 
Standard only). While OSHA is proposing to retain these provisions, it 
is also proposing to replace the terms ``high-efficiency filters'' and 
``high-efficiency particulate filters'' with the term ``HEPA filters.'' 
These three terms have the same meaning, so use of the term ``HEPA'' 
would impose no additional burden on employers, nor would it diminish 
employee protection. The Agency believes that the usual and customary 
practice among employers in the cotton-dust industry is to use HEPA 
filters with air-purifying respirators; therefore, employers should 
experience no additional burden, and employee protection should remain 
at current levels, as a result of this revision. In addition, the 
proposed revision would make the filter requirements of the Cotton Dust 
Standard consistent with other OSHA substance-specific standards and 
with its Respiratory Protection Standard, thereby reducing any 
confusion that may exist among the regulated community regarding the 
appropriate filter to use with air-purifying respirators.
    [sbull] Footnote 2 to Table II of 29 CFR 1910.1018 (Inorganic 
Arsenic Standard). This provision prohibits the use of half-mask 
respirators for protection against arsenic trichloride because it is 
rapidly absorbed through the skin. OSHA is retaining this provision to 
protect employees from the cumulative toxic effects that result from 
skin absorption.
    [sbull] Footnote 2 to Table II of 29 CFR 1910.1025, and footnote 2 
to Table 1 of 29 CFR 1926.62 (Lead Standard). These footnotes specify 
that employers must provide employees with full facepiece respirators 
when employees experience eye or skin irritation that results from 
exposure to lead aerosols at use concentrations. These provisions 
prevent serious eye and skin injuries among employees.
    [sbull] Footnote b to Table 2 of 29 CFR 1910.1027 and footnote b to 
Table 1 of

[[Page 34110]]

29 CFR 1926.1127 (Cadmium Standard). These provisions require a full 
facepiece respirator when an employee experiences eye irritation, 
thereby reducing the risk of eye injury among employees.
    [sbull] Table 1 of 29 CFR 1910.1047 (Ethylene Oxide (EtO) 
Standard). This table lists only full facepiece respirators, or 
respirators with hoods or helmets, implying that employers must not 
select half-mask respirators for protection against EtO. The preamble 
to the final EtO Standard states:

    The record reflects that high exposures to EtO have been shown 
to cause eye irritation and that such effects may occur at exposures 
that may be reached for short periods. Therefore, OSHA has chosen to 
retain the requirement for full-facepiece respirators in the final 
rule. (49 FR 25781)

Accordingly, in this proposal the Agency is making explicit the 
prohibition against the use of half-mask respirators to ensure that 
employers select only those respirators (i.e., full facepiece 
respirators, and respirators with hoods or helmets) that OSHA found, in 
the earlier rulemaking, will provide the requisite level of protection 
to their employees.
    [sbull] Footnote 2 to Table 1 of 29 CFR 1910.1048 (Formaldehyde 
Standard). This provision requires that employers who select half-mask 
respirators instead of full facepiece respirators for formaldehyde 
exposures up to 7.5 ppm provide effective gas-proof goggles for 
employees to use in combination with the half-mask respirators.
    [sbull] Table 2 of 29 CFR 1910.1052 (Methylene Chloride (MC) 
Standard). This table lists only full facepiece respirators, or 
respirators with hoods or helmets, thereby indicating that employers 
are not to select half-mask respirators for protection against MC. In 
the preamble to the final MC Standard, the Agency states:

    OSHA has determined that this standard is necessary because 
exposure to MC places employees at significant risk of developing 
exposure-related adverse health effects. These effects include * * * 
skin and eye irritation. (62 FR 1572)

Later in the preamble, the Agency states that ``employers are required 
to provide employees who are at risk of skin and/or eye contact with MC 
with appropriate protective clothing and eye protection.'' (See 62 FR 
1589.)
    The risk of MC-related skin and eye irritation and the need for 
proper skin and eye protection convinced OSHA to limit respirator 
selection to full facepiece respirators and respirators with hoods and 
helmets in the final MC Standard to ensure that employees' facial skin 
and eyes are protected during MC exposure. Here the Agency is directly 
prohibiting the selection of half-masks, and explicitly limiting 
respirator selection to respirators (i.e., full facepiece respirators, 
and respirators with hoods or helmets) that would provide the 
appropriate level of protection to employees.
    [sbull] Lines 10 and 11 under ``Respirator type'' in Table 1 of 29 
CFR 1910.1028 (Benzene Standard); lines 6-11 under ``Respirator type'' 
in Table 1 of 29 CFR 1910.1044 (1,2-dibromo-3-chloropropane Standard); 
lines 16 and 17 under ``Respirator type'' in Table I of 29 CFR 
1910.1045 (Acrylonitrile Standard); line12 under ``Minimum required 
respirator'' in Table 1 of 29 CFR 1910.1047 (Ethylene Oxide Standard); 
lines 11-13 under ``Minimum respirator required'' in Table 1 of 29 CFR 
1910.1048 (Formaldehyde Standard); lines 8-10 under ``Respirator type'' 
in Table 1 of 29 CFR 1910.1050 and 1926.60 (Methylenedianiline 
Standards); lines 13 and 14 under ``Minimum respirator required'' in 
Table 2 of 29 CFR 1910.1052 (Methylene Chloride Standard).
    These provisions specify which respirators employers are to use 
under emergency-escape conditions. With regard to respirators used for 
escape, OSHA adopts the same position it did in the final rulemaking 
for the Respiratory Protection Standard. In the final rulemaking for 
this standard, the Agency noted the variety of escape respirators 
permitted under its substance-specific standards, and found that these 
standards addressed hazards associated with many different substances 
and escape situations. In support of this conclusion, the Agency cited 
the following examples:

    [U]nder current 29 CFR 1910.1050, the standard covering exposure 
to methylenedianiline (MDA), escape respirators may be any full 
facepiece air-purifying respirator equipped with HEPA cartridges, or 
any positive pressure or continuous flow self-contained breathing 
apparatus with full facepiece or hood; for formaldehyde exposure, 
escape respirators may be a full facepiece with chin style, front, 
or back-mounted industrial canister approved against formaldehyde 
(29 CFR 1910.1048).

(63 FR 1202.) As noted earlier in this section, the adverse physical 
effects of specific substances (e.g., skin and eye irritation) often 
limit respirator selection; these limitations would apply as well to 
the selection of escape respirators. Accordingly, OSHA is retaining the 
requirements for escape respirators identified in the existing 
substance-specific standards because previous rulemakings identified 
these respirators based on the unique characteristics of the regulated 
substances, as well as the conditions under which employees must use 
escape respirators.
    As is required currently, respirators covered by these emergency-
escape provisions must meet the requirements of paragraph (d)(2)(ii) of 
OSHA's Respiratory Protection Standard, which specifies that these 
respirators must be NIOSH-certified for escape from the atmosphere in 
which employees will use them. In addition, employees are to use these 
respirators only for escaping from, not entering, IDLH atmospheres. For 
entering such atmospheres, paragraph (d)(2)(i) of the Respiratory 
Protection Standard requires that employees use only full facepiece, 
pressure demand SCBAs certified by NIOSH for a minimum service life of 
30 minutes, or full facepiece, pressure demand SARs with an auxiliary 
self-contained air supply.
    [sbull] Paragraphs (g)(2)(ii) of 29 CFR 1910.1001, (h)(2)(iii)(A) 
of 29 CFR 1915.1001, and (h)(3)(ii) of 29 CFR 1926.1101 (Asbestos 
Standards); (f)(3)(ii) of 29 CFR 1910.1025 (Lead Standard); (f)(3)(ii) 
of 29 CFR 1910.1043 (Cotton Dust Standard); and (g)(3)(iii) of 29 CFR 
1910.1048 (Formaldehyde Standard).
    These paragraphs require employers to upgrade a negative pressure 
respirator, or a non-powered air-purifying respirator in the case of 
the Cotton Dust Standard, to a tight-fitting powered air-purifying 
respirator (PAPR) when the employee chooses to use a tight-fitting 
PAPR; for the Formaldehyde Standard, this requirement applies when the 
employee has difficulty using a negative pressure respirator and the 
tight-fitting PAPR provides the employee with adequate protection 
against the airborne contaminant. OSHA is proposing to retain these 
requirements because tight-fitting PAPRs increase the protection 
provided to employees when the respirator-selection provisions identify 
a low-end respirator (i.e., a negative pressure respirator or a non-
powered air-purifying respirator) for use.
    [sbull] Paragraph (h)(2)(iii)(B) of 29 CFR 1915.1001 (Asbestos 
Standard). The Agency also is proposing to retain this paragraph in the 
Asbestos Standard for Shipyards, which specifies that employers must 
inform employees that they (the employees) may require employers to 
provide them with a tight-fitting PAPR instead of a negative pressure 
respirator. This requirement provides an extra margin of protection to 
employees by ensuring that

[[Page 34111]]

employers take positive action to inform them of their option to 
upgrade to a more protective respirator than the one that they would 
normally receive for use when exposed to asbestos.
    [sbull] While the paragraphs described in the previous section 
require employers to upgrade employee respirators, every substance-
specific standard has a provision, usually as a footnote to its APF 
table, that gives employers discretion to select respirators that 
provide employees with more protection from atmospheric contaminants 
than the required respirator. Under this proposal, the Agency would 
consolidate this discretionary alternative into a generic provision in 
proposed paragraph (d)(3)(i)(A) of the Respiratory Protection Standard 
(i.e., ``[employees must * * * select a respirator that meets or 
exceeds the required level of employee protection'' [emphasis added]). 
The Agency concludes that relocating this provision in proposed 
paragraph (d)(3)(i)(A) of the Respiratory Protection Standard will 
highlight this alternative to employers, and will encourage more of 
them to select more protective respirators for their employees than is 
now the case.
4. Substantive Revisions to the Respirator-Selection Requirements in 
Substance-Specific Standards
    OSHA is proposing to revise respirator-selection requirements in 
several substance-specific standards that regulate employee exposure to 
organic-vapor substances. The following sections describe these 
proposed revisions.
    [sbull] Paragraphs (g)(2) of 29 CFR 1910.1017 (Vinyl Chloride 
Standard), (g)(2)(i) of 29 CFR 1910.1028 (Benzene Standard), (h)(2)(i) 
of 29 CFR 1910.1045 (Acrylonitrile Standard), and (g)(2)(i) of 29 CFR 
1910.1048 (Formaldehyde Standard). These paragraphs exempt employers 
from paragraphs (d)(3)(iii)(B)(1) and (B)(2) of OSHA's Respiratory 
Protection Standard; the exempted paragraphs consist of respirator-
selection provisions that protect employees against gases and vapors. 
Because OSHA would be removing the existing change schedules from these 
substance-specific standards under this proposed rulemaking, it becomes 
necessary to identify requirements that it believes would provide 
employees with at least the same level of protection as the existing 
provisions. These requirements are paragraphs (d)(3)(iii)(B)(1) and 
(B)(2) of its Respiratory Protection Standard; by removing the current 
exemptions, employers would apply paragraphs (d)(3)(iii)(B)(1) and 
(B)(2) of the Respiratory Protection Standard to select respirators 
that protect employees against the gases and vapors regulated by these 
substance-specific standards. In addition, this revision would provide 
employers with increased flexibility in selecting respirators without 
adding to their compliance burden (i.e., their existing respirator-
selection procedures would be acceptable under this revision). (Note 
that the exemption would still remain for the 1,3-Butadiene Standard 
because, as noted above, the Agency is retaining the existing 
respirator-selection provisions of that standard.)
    [sbull] Paragraph (g)(2)(ii) of 29 CFR 1910.1048 (Formaldehyde 
Standard). This paragraph specifies a change schedule for chemical 
cartridges and canisters used for formaldehyde exposures that do not 
have an end-of-service life indicator (ESLI) approved by NIOSH. OSHA is 
proposing that employers select respirators according to paragraphs 
(d)(3)(iii)(B)(1) and (B)(2) of its Respiratory Protection Standard 
instead of these requirements.
    The paragraphs proposed for removal require employers who use a 
change schedule to select a cartridge or canister that has a NIOSH-
approved ESLI, or to use a change schedule for which they must provide 
``objective information or data that will ensure that canisters and 
cartridges are changed before the end of their service life'' (see 
paragraph (d)(3) of OSHA's Respiratory Protection Standard). When they 
choose the latter option, this revision would limit the change schedule 
to one work shift because of possible vapor migration in the cartridges 
and canisters during storage. The Agency believes that this revision 
would: Provide employers with flexibility to use other change schedules 
when a NIOSH-approved ESLI is not available; not increase the 
regulatory burden of employers because the existing change schedule 
would remain valid; and ensure that employees receive at least the same 
level of protection as they receive with the existing change schedule, 
because employers must use a change schedule that they can demonstrate 
is safe for this purpose.
5. Use of Plain Language for Proposed Revisions
    Whenever possible, OSHA is using plain language in revising the 
regulatory text of the substance-specific standards identified in this 
proposal. The Agency believes that this approach improves the 
comprehensibility and uniformity of the proposed revisions. OSHA 
believes that these improvements would enhance employer compliance with 
the provisions, thereby increasing the level of protection afforded to 
employees.
6. Summary of Superseding Actions
    The following table summarizes OSHA's proposed revisions to 
existing substance-specific standards. This table lists only those 
provisions for which the Agency is proposing substantive revisions 
(e.g., proposing to replace existing requirements with new 
requirements); it does not list provisions that OSHA is proposing to 
retain in their present form (although the Agency is rewriting them in 
plain language).

          Summary of Superseding Actions for Specific Standards
------------------------------------------------------------------------
                                               Proposed action (29 CFR
      Existing section  (29 CFR 1910)                   1910)
------------------------------------------------------------------------
1001(g)(2)(ii)............................  Revise.
1001(g)(3)................................  Remove Table 1 and revise.
1001(l)(3)(ii)............................  Redesignate Table 2 as Table
                                             1.
1017(g)(3)(i).............................  Remove table and revise.
1017(g)(3)(iii)...........................  Remove.
1018 Tables I and II......................  Remove.
1018(h)(3)(i).............................  Revise.
1018(h)(3)(ii)............................  Remove.
1018(h)(3)(iii)...........................  1018(h)(3)(ii).
1025(f)(2)(ii)............................  Remove Table II.
1025(f)(3)(i).............................  Revise.
1027(g)(3)(i).............................  Remove Table 2 and revise.
1028(g)(3)(ii)............................  Remove Table 1.
1028(g)(2)(i).............................  Revise.
1028(g)(3)(i).............................  Revise.
1029(g)(3)................................  Remove Table I and revise.
1043(f)(3)(i).............................  Remove Table I and revise.
1043(f)(3)(ii)............................  Revise.
1044(h)(3)................................  Remove Table I and revise.
1045(h)(2)(i).............................  Revise.
1045(h)(3)................................  Remove Table I and revise.
1047(g)(3)................................  Remove Table I and revise.
1048(g)(2)................................  Revise.
1048(g)(3)................................  Remove Table 1 and revise.
1050(h)(3)(i).............................  Remove Table 1 and revise.
1052(g)(3)................................  Remove Table 2 and revise.
------------------------------------------------------------------------


 
------------------------------------------------------------------------
                                              Proposed action  (29 CFR
      Existing section  (29 CFR 1915)                   1915)
------------------------------------------------------------------------
1001(h)(2)(i) through (h)(2)(v)...........  Remove Table 1 and revise.
------------------------------------------------------------------------


[[Page 34112]]


 
------------------------------------------------------------------------
                                               Proposed action (29 CFR
      Existing section (29 CFR 1926)                    1926)
------------------------------------------------------------------------
60(i)(3)(i)...............................  Remove Table 1 and revise.
62(f)(3)(i)...............................  Remove Table 1 and revise.
1101(h)(3)(i) through (h)(3)(iv)..........  Remove Table 1 and revise.
1127(g)(3)(i).............................  Remove Table 1 and revise.
------------------------------------------------------------------------

    Section XII (``Proposed Amendments to Standards'') of this notice 
provides the full regulatory text of the proposed revisions to OSHA's 
existing substance-specific standards dealing with respirator 
selection. This section describes both substantive revisions proposed 
for the existing respirator-selection requirements, as well as 
respirator-selection requirements retained in their current form but 
rewritten in plain language.

VIII. Issues

    OSHA requests the public to comment on, and to provide additional 
information regarding, any of the issues listed below. Please provide a 
detailed explanation of each response you make.

Developing and Updating APFs

    1. Is the method used by OSHA in developing the proposed APFs 
appropriate? OSHA used a multi-faceted approach incorporating both 
analyses of data collected in WPF and SWPF studies, as well as OSHA's 
review of all relevant materials. OSHA requests comment on the 
usefulness of this approach to data collection.
    2. Are there any additional studies that may be useful in 
determining APFs, that have not already been identified by OSHA in 
Section IV of this proposal? Please provide these to the Agency.
    3. Are statistical analyses, treatments, or approaches, other than 
those described in Section IV of the proposal, available for 
differentiating between or comparing the highly variable respirator-
performance data?
    4. OSHA is aware of discussions within the respirator community 
indicating some sentiment for setting APFs for filtering facepiece 
respirators at 5, and for setting an APF of 10 for other half-mask air-
purifying respirators. Based upon OSHA's reviews, OSHA cannot 
differentiate between the performance of the two types of respirator, 
and OSHA finds compelling evidence from the large number of observed 
data points (N = 917 Co/Ci pairs) to support proposing an APF of 10 for 
both of these classes of respirators. Is there evidence that a 
different APF should be provided for these respirator classes?
    5. While there are no WPF or SWPF studies for quarter-mask 
respirators, the 1976 LANL Respiratory Protection Factor by Hyatt found 
protection factors ranging from 5 to 10. Should OSHA continue to 
include quarter-masks in the half-mask class, or separate them into a 
class of their own with and APF of 5?
    6. OSHA is proposing a method by which to separate loose-fitting 
facepiece supplied-air and PAPR hood/helmet respirators from the 
better-performing hood/helmet respirators. Respirator performance 
studies have shown that some PAPR and continuous-flow supplied-air 
respirators provide greater protection than others of the same class. 
The 1987 NIOSH Respirator Decision Logic gives an APF of 25 for all of 
these respirators while ANSI's 1992 respirator standard gives an APF of 
25 to loose-fitting facepiece models and an APF of 1000 to hood/helmet 
models. OSHA is proposing an APF of 25 except for those models that 
ensure the maintenance of a positive pressure inside the facepiece 
during use, consistent with a protection factor of 1000 or greater, in 
which case those models would receive an APF of 1000. Is this the 
appropriate method by which to distinguish high-performing hood/helmet 
respirators from others?
    7. The assigned protection factor for a full facepiece respirator 
in Table 1 of the proposed standard does not currently take into 
account the type of particulate filter that is used. An N95 particulate 
filter could potentially, under a worst case scenario, have up to 5% 
leakage through the filter. This would decrease the APF for a full 
facepiece respirator to a maximum of 20 when N95 filters are used. 
Should OSHA take into account the limitations of the filter and assign 
an APF of 20 for full facepiece respirators when N95 filters are used?
    8. Other Federal Agencies, such as the Nuclear Regulatory 
Commission (NRC), have set no APF for filtering facepiece air-purifying 
respirators (APRs) for use in their particular work environments. In 
some cases, such APRs are not allowed to be used at all. In other 
settings, e.g., the healthcare industry, some employers rely very 
heavily upon such APRs to protect their employees who work with 
patients who have infectious airborne illnesses. How should OSHA 
incorporate such information, if at all, into an APF requirement for 
all industries under OSHA's jurisdiction?
    9. Proper facepiece fit is important in achieving the proposed APF 
for tight-fitting respirators. Accordingly, the Agency would appreciate 
receiving information on current testing and procedures used by 
respirator manufacturers to ensure that the facepieces they make will 
fit respirator users properly.
    10. When a limiting factor such as IDLH, LEL, or the performance 
limit specified for a cartridge and canister by the manufacturers are 
less than the calculated MUC, proposed paragraph (d)(3)(i)(B)(4) 
requires employers to set the MUC at the lower limit. Accordingly, OSHA 
is seeking comment on the following questions:
    a. What other limiting factors should OSHA include as examples in 
this proposed paragraph?
    b. Should the Agency specify the LEL or 10% of the LEL as the 
limiting factor?
    11. Some hazardous substances found in the workplace do not have an 
OSHA PEL. However, a number these substances may have an exposure limit 
designated by sources other than OSHA (e.g., recommended by the 
chemical manufacturer, ACGIH, NIOSH, EPA). Accordingly, the Agency is 
asking for comment on the following issues involving MUCs:
    a. Should OSHA expand the definition and application of MUC to 
hazardous substances that it does not regulate?
    b. Should the Agency require employers to determine MUCs for 
substances that have no OSHA PEL (i.e., substances not regulated 
specifically by OSHA), and to base respirator selection on such a 
determination?
    c. For hazardous substances that OSHA does regulate, should it 
require employers to comply with the MUC values developed by NIOSH when 
these values are lower than the calculated MUC values (i.e., MUC = APF 
x PEL)?
    12. A prevailing view is that exposure to multiple contaminants in 
the workplace affect the performance of respirator filters and 
cartridges differently than exposure to single contaminants. To assist 
it in developing MUCs for single and multiple contaminants, OSHA is 
asking the public to address the following issues:
    a. What information and data are available that either support or 
do not support this view?
    b. Should MUCs for contaminant mixtures differ from MUCs for single 
mixtures?
    13. Section VII proposes to revise most of the respirator-selection 
requirements in OSHA's substance-specific standards. Accordingly, the 
Agency is asking for comment on the following questions:
    a. This proposal excludes the respirator-selection provisions of 
the 1,3-Butadiene Standard from any revision. Is this exclusion 
warranted?

[[Page 34113]]

    b. Special or unique respirator-selection requirements in the 
substance-specific standards (e.g., requirements for emergency-escape, 
HEPA filters, upgrading respirators at the employee's request, eye 
protection) remain largely intact. Should the Agency standardize these 
provisions across all of its substance-specific standards, and, if so, 
what requirements should it standardize.
    14. The Agency has developed its Preliminary Economic Analysis 
(PEA) based on survey data indicating what types of respirators 
employees are using currently. The Agency does not, however, have data 
on the exposure levels as a multiple of the PEL that respirator users 
are currently exposed to. For the purposes of this analysis, the Agency 
has used its internal Integrated Management and Information System 
(IMIS) data to estimate the distribution of exposures as a multiple of 
the PEL. The Agency also assumes that employers are currently using the 
respirator with the lowest possible costs that can still satisfy 
existing guidance on APFs, allowing employees to be exposed up to the 
full limit of a currently assigned APF for that class of respirator. 
OSHA seeks comment on whether other data sources or methodologies for 
making this projection exist.
    a. Is it common for employers to put employees in respirators at 
the highest exposure levels permitted by the APF range?
    b. Are there particular types of respirators that frequently do not 
fit this pattern (i.e., are selected for reasons other than having a 
high APF or due to a medical reason for a particular employee)?
    c. How do employers approach the issue of uncertainty in possible 
exposure levels when integrating APFs into their respirator selection?
    d. To what extent will having a single OSHA APF table result in 
less confusion than the existing multiplicity of APF tables?
    e. Do OSHA's cost estimates of using different types of respirators 
adequately represent all of the costs associated with each type of 
respirator use?
    f. Are their any alternative approaches consistent with the OSH Act 
that could reduce the burden of this standard on small entities?

IX. Public Participation--Comments and Hearings

    OSHA encourages members of the public to participate in this 
rulemaking by submitting comments on the proposal, and by providing 
oral testimony and documentary evidence at the informal public hearing 
that the Agency will convene after the comment period ends. In this 
regard, the Agency invites interested parties having knowledge of, or 
experience with, APFs and MUCs to participate in this process, and 
welcomes any pertinent data and cost information that will provide it 
with the best available evidence on which to develop the final 
regulatory requirements.
    This section describes the procedures the public must use to submit 
their comments to the docket in a timely manner, and to schedule an 
opportunity to deliver oral testimony and provide documentary evidence 
at the informal public hearings. Comments, notices of intention to 
appear, hearing testimony, and documentary evidence will be available 
for inspection and copying at the OSHA Docket Office. You also should 
read the sections above titled DATES and ADDRESSES for additional 
information on submitting comments, documents, and requests to the 
Agency for consideration in this rulemaking.
    Written Comments. OSHA invites interested parties to submit written 
data, views, and arguments concerning this proposal. In particular, 
OSHA would encourage interested parties to comment on the issues raised 
in section VIII (``Issues'') of the preamble. When submitting comments, 
parties must follow the procedures specified above in the sections 
titled DATES and ADDRESSES. The comments must clearly identify the 
provision of the proposal you are addressing, the position taken with 
respect to each issue, and the basis for that position. Comments, along 
with supporting data and references, received by the end of the 
specified comment period will become part of the proceedings record, 
and will be available for public inspection and copying at the OSHA 
Docket Office.
    Informal Public Hearings. Pursuant to section 6(b)(3) of the Act, 
members of the public will have an opportunity at an informal public 
hearing to provide oral testimony concerning the issues raised in this 
proposal. The hearings will commence at 9:30 a.m. on the first day. At 
that time, the presiding administrative law judge (ALJ) will resolve 
any procedural matters relating to the proceeding. The hearings will 
reconvene on subsequent days at 8:30 a.m.
    The legislative history of section 6 of the OSH Act, as well as 
OSHA's regulation governing public hearings (29 CFR 1911.15), establish 
the purpose and procedures of informal public hearings. Although the 
presiding officer of such hearings is an ALJ, and questioning by 
interested parties is allowed on crucial issues, the proceeding is 
informal and legislative in purpose. Therefore, the hearing provides 
interested parties with an opportunity to make effective and 
expeditious oral presentations in the absence of procedural restraints 
or rigid procedures that could impede or protract the rulemaking 
process. In addition, the hearing is an informal administrative 
proceeding, rather than adjudicative one in which the technical rules 
of evidence would apply, because its primary purpose is to gather and 
clarify information. The regulations that govern public hearings, and 
the pre-hearing guidelines issued for this hearing, will ensure 
participants fairness and due process, and also will facilitate the 
development of a clear, accurate, and complete record. Accordingly, 
application of these rules and guidelines will be such that questions 
of relevance, procedure, and participation generally will favor 
development of the record.
    Conduct of the hearing will conform to the provisions of 29 CFR 
part 1911, ``Rules of Procedure for Promulgating, Modifying, or 
Revoking Occupational Safety and Health Standards.'' The regulation at 
29 CFR 1911.4 ``Additional or Alternative Procedural Requirements,'' 
specifies that the Assistant Secretary may, on reasonable notice, issue 
alternative procedures to expedite proceedings or for other good cause. 
Although the ALJs who preside over these hearings make no decision or 
recommendation on the merits of OSHA's proposal, they do have the 
responsibility and authority to ensure that the hearing progresses at a 
reasonable pace and in an orderly manner.
    To ensure that interested parties receive a full and fair informal 
hearing as specified by 29 CFR part 1911, the ALJ has the authority and 
power to: Regulate the course of the proceedings; dispose of procedural 
requests, objections, and comparable matters; confine the presentations 
to matters pertinent to the issues raised; use appropriate means to 
regulate the conduct of the parties who are present at the hearing; 
question witnesses, and permit others to question witnesses; and limit 
the time for such questioning. At the close of the hearing, the ALJ 
will establish a post-hearing comment period for parties who 
participated in the hearing. During the first part of this period, the 
participants may submit additional data and information to OSHA, while 
during the second part of this period, they may submit briefs, 
arguments, and summations.
    Notice of Intention To Appear To Provide Testimony at the Informal

[[Page 34114]]

Public Hearings. Interested parties who intend to provide oral 
testimony at the informal public hearings must file a notice of 
intention to appear by using the procedures specified above in the 
sections titled DATES and ADDRESSES. This notice must provide the: 
Name, address, and telephone number of each individual who will provide 
testimony, and their preferred hearing location; capacity (e.g., name 
of the establishment/organization the individual is representing; the 
individual's occupational title and position) in which each individual 
will testify; approximate amount of time required for each individual's 
testimony; specific issues each individual will address, including a 
brief statement of the position that the individual will take with 
respect to each of these issues; and any documentary evidence the 
individual will present, including a brief summary of the evidence.
    OSHA emphasizes that the hearings are open to the public, and that 
interested parties are welcome to attend. However, only a party who 
files a proper notice of intention to appear may ask questions and 
participate fully in the proceedings. While a party who did not file a 
notice of intention to appear may be allowed to testify at the hearing 
if time permits, this determination is at the discretion of the 
presiding ALJ.
    Hearing Testimony and Documentary Evidence. Any party requesting 
more than 10 minutes to testify at the informal public hearing, or who 
intends to submit documentary evidence at the hearing, must provide the 
complete text of the testimony and the documentary evidence as 
specified above in the sections titled DATES and ADDRESSES. The Agency 
will review each submission and determine if the information it 
contains warrants the amount of time requested. If OSHA believes the 
requested time is excessive, it will allocate an appropriate amount of 
time to the presentation, and will notify the participant of this 
action, and the reasons for the action, prior to the hearing. The 
Agency may limit to 10 minutes the presentation of any participant who 
fails to comply substantially with these procedural requirements; in 
such instances, OSHA may request the participant to return for 
questioning at a later time.
    Certification of the Record and Final Determination After the 
Informal Public Hearing. Following the close of the hearing and post-
hearing comment period, the presiding ALJ will certify the record to 
the Assistant Secretary of Labor for Occupational Safety and Health; 
the record will consist of all of the written comments, oral testimony, 
and documentary evidence received during the proceeding. However, the 
ALJ does not make or recommend any decisions as to the content of the 
final standard. Following certification of the record, OSHA will review 
the proposed APF provisions in light of all the evidence received as 
part of the record, and then will issue the final APF provisions based 
on the entire record.

List of Subjects in 29 CFR Parts 1910, 1915, and 1926

    Assigned protection factors, Hazardous substances, Health, 
Occupational safety and health, Respirators, Respirator selection.

Authority and Signature

    John L. Henshaw, Assistant Secretary of Labor for Occupational 
Safety and Health, U.S. Department of Labor, 200 Constitution Ave., 
NW., Washington, DC 20210, directed the preparation of this notice. The 
Agency issues the proposed sections under the following authorities: 
Sections 4, 6(b), 8(c), and 8(g) of the Occupational Safety and Health 
Act of 1970 (29 U.S.C. 653, 655, 657); section 107 of the Contract Work 
Hours and Safety Standards Act (the Construction Safety Act) (40 U.S.C. 
333); section 41, the Longshore and Harbor Worker's Compensation Act 
(33 U.S.C. 941); Secretary of Labor's Order No. 5-2002 (67 FR 65008); 
and 29 CFR Part 1911.

    Signed at Washington, DC, on May 28, 2003.
John L. Henshaw,
Assistant Secretary of Labor.

X. Proposed Amendments to Standards

    OSHA proposes to amend 29 CFR parts 1910, 1915, and 1926 as 
follows:

PART 1910--[AMENDED]

Subpart I--[Amended]

    1. The authority citation for subpart I of part 1910 is revised to 
read as follows:

    Authority: Sections 4, 6, and 8 of the Occupational Safety and 
Health Act of 1970 (29 U.S.C. 653, 655, and 657); and Secretary of 
Labor's Order No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 
FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 111), or 3-2000 (62 FR 
50017).
    Sections 1910.132, 1910.134, and 1910.138 or 29 CFR also issued 
under 29 CFR part 1911.
    Sections 1910.133, 1910.135, and 1910.136 of 29 CFR also issued 
under 29 CFR part 1911 and 5 U.S.C. 553.

    2. Section 1910.134 is amended as follows:
    a. The text of the definitions for ``Assigned protection factor 
(APF)'' and ``Maximum use concentration (MUC)'' is added to paragraph 
(b);
    b. The text of paragraphs (d)(3)(i)(A) and (d)(3)(i)(B) is added; 
and
    c. Paragraph (n) is revised.
    The added and revised text read as follows:


Sec.  1910.134  Respiratory protection.

* * * * *
    (b) * * *
    Assigned protection factor (APF) means the workplace level of 
respiratory protection that a respirator or class of respirators is 
expected to provide to employees when the employer implements a 
continuing, effective respiratory protection program as specified by 29 
CFR 1910.134.
* * * * *
    Maximum use concentration (MUC) means the maximum atmospheric 
concentration of a hazardous substance from which an employee can be 
expected to be protected when wearing a respirator, and is determined 
by the assigned protection factor of the respirator or class of 
respirators and the exposure limit of the hazardous substance. The MUC 
usually can be determined mathematically by multiplying the assigned 
protection factor specified for a respirator by the permissible 
exposure limit, short term exposure limit, ceiling limit, peak limit, 
or any other exposure limit used for the hazardous substance.
* * * * *
    (d) * * *
    (3) * * *
    (i) * * *
    (A) Assigned Protection Factors (APFs). Employers must use the 
assigned protection factors listed in Table I to select a respirator 
that meets or exceeds the required level of employee protection. When 
using a combination respirator (e.g., airline respirators with an air-
purifying filter), employers must ensure that the assigned protection 
factor is appropriate to the mode of operation in which the respirator 
is being used.

    Note to paragraph (d)(3)(i)(A): The assigned protection factors 
listed in Table I are effective only when the employer has a 
continuing, effective respiratory protection program as specified by 
29 CFR 1910.134, including training, fit testing, maintenance and 
use requirements. These assigned protection factors do not apply to 
respirators used solely for escape.


[[Page 34115]]



                                      Table I.--Assigned Protection Factors
----------------------------------------------------------------------------------------------------------------
                                                                                                   Loose-fitting
           Type of respirator 1 2                Half mask     Full facepiece      Helmet/hood       facepiece
----------------------------------------------------------------------------------------------------------------
1. Air-Purifying Respirator.................            3 10                50  ................  ..............
2. Powered Air-Purifying Respirator (PAPR)..              50              1000            4 1000              25
3. Supplied-Air Respirator (SAR) or Airline
 Respirator:
    [sbull] Demand mode.....................              10                50  ................  ..............
    [sbull] Continuous-flow mode............              50             1,000           4 1,000              25
    [sbull] Pressure-demand or other                      50             1,000  ................  ..............
     positive-pressure mode.................
4. Self-Contained Breathing Apparatus
 (SCBA):
    [sbull] Demand mode.....................              10                50                50  ..............
    [sbull] Pressure-demand or other          ..............            10,000            10,000  ..............
     positive-pressure mode (e.g., open/                           5 (maximum)       5 (maximum)
     closed circuit)........................
----------------------------------------------------------------------------------------------------------------
Notes:
\1\ Employers may select respirators assigned for use in higher workplace concentrations of a hazardous
  substance for use at lower concentrations of that substance or when required respirator use is independent of
  concentration.
\2\ The assigned protection factors in Table I only apply when the employer implements a continuing, effective
  respirator program as specified by OSHA's Respiratory Protection Standard at 29 CFR 1910.134, including
  training, fit testing, maintenance and use requirements.
\3\ This APF category includes quarter masks, filtering facepieces, and half-masks.
\4\ Previous studies involving Workplace Protection Factor (WPF) and Simulated Workplace Protection Factor
  (SWPF) testing on helmet/hood respirators show that some of these respirators do not provide a level of
  protection consistent with an APF of 1000. Therefore, only helmet/hood respirators that ensure the maintenance
  of a positive pressure inside the facepiece during use, consistent with performance at a level of protection
  of 1000 or greater, receive an APF of 1000. All other helmet/hood respirators are treated as loose-fitting
  facepiece respirators and receive an APF of 25.
\5\ Although positive pressure SCBAs appear to provide the highest level of respiratory protection, a SWPF study
  of SCBA users concluded that all users may not achieve protection factors of 10,000 at high work rates. When
  employers can estimate hazardous concentrations for planning purposes, they must use a maximum assigned
  protection factor no higher than 10,000.

    (B) Maximum Use Concentration (MUC). (1) The employer must select a 
respirator for employee use that maintains the employee's exposure to 
the hazardous substance, when measured outside the respirator, at or 
below the MUC.

    Note to paragraph (d)(3)(i)(B)(1): MUCs are effective only when 
the employer has a continuing, effective respiratory protection 
program as specified by 29 CFR 1910.134, including training, fit 
testing, maintenance and use requirements.

    (2) Employers must comply with the respirator manufacturer's MUC 
for a hazardous substance when the manufacturer's MUC is lower than the 
calculated MUC specified by this standard.
    (3) Employers must not apply MUCs to conditions that are 
immediately dangerous to life or health (IDLH); instead, they must use 
respirators listed for IDLH conditions in paragraph (d)(2) of this 
standard.
    (4) When the calculated MUC exceeds another limiting factor such as 
the IDLH level for a hazardous substance, the lower explosive limit 
(LEL), or the performance limits of the cartridge or canister, then 
employers must set the maximum MUC at that lower limit.
* * * * *
    (n) Effective date. Paragraphs (d)(3)(i)(A) and (d)(3)(i)(B) of 
this section become effective September 4, 2003.
* * * * *

Subpart Z--[Amended]

    3. The general authority citation for subpart Z of part 1910 is 
revised to read as follows:

    Authority: Sections 4, 6, and 8 of the Occupational Safety and 
Health Act of 1970 (29 U.S.C. 653, 655, and 657); Secretary of 
Labor's Orders 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR 
35736), 1-90 (55 FR 9033), 6-96 (62 FR 111), or 3-2000 (62 FR 
50017); and 29 CFR Part 1911.
* * * * *
    4. Section 1910.1001 is amended by:
    a. Removing Table 1 in paragraph (g)(3);
    b. Redesignating Table 2 in paragraph (l)(3)(ii) as Table 1;
    c. Removing the reference to ``Table 2'' in paragraph (l)(3)(ii) 
and adding ``Table 1'' in its place; and
    d. Revising paragraphs (g)(2)(ii) and (g)(3).
    The revisions read as follows:


Sec.  1910.1001  Asbestos.

* * * * *
    (g) * * *
    (2) * * *
    (ii) Employers must provide an employee with tight-fitting, powered 
air-purifying respirator (PAPR) instead of a negative-pressure 
respirator selected according to paragraph (g)(3) of this standard when 
the employee chooses to use a PAPR and it provides adequate protection 
to the employee.
* * * * *
    (3) Respirator selection. Employers must:
    (i) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however, 
employers must not select or use filtering-facepiece respirators for 
protection against asbestos fibers.
    (ii) Provide HEPA filters for air-purifying respirators.
* * * * *
    5. In Sec.  1910.1017, remove the table in paragraph (g)(3)(i), 
remove paragraph (g)(3)(iii), and revise paragraph (g)(3)(i) to read as 
follows:


Sec.  1910.1017  Vinyl chloride.

* * * * *
    (g) * * *
    (3) * * * (i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (B) Provide an organic-vapor cartridge that has a service life of 
at least one hour when using a chemical-cartridge respirator at vinyl 
chloride concentrations up to 10 ppm.
    (C) Select a canister that has a service life of at least four 
hours when using a powered air-purifying respirator having a hood, 
helmet, or full or half facepiece, or a gas mask with a front- or back-
mounted canister, at vinyl chloride concentrations up to 25 ppm.
* * * * *
    6. In Sec.  1910.1018, remove Tables I and II and paragraph 
(h)(3)(ii), redesignate paragraph (h)(3)(iii) as paragraph

[[Page 34116]]

(h)(3)(ii), and revise paragraph (h)(3)(i) to read as follows:


Sec.  1910.1018  Inorganic arsenic.

* * * * *
    (h) * * *
    (3) * * *(i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (B) Ensure that employees do not use half-mask respirators for 
protection against arsenic trichloride because it is absorbed rapidly 
through the skin.
    (C) Provide HEPA filters for air-purifying respirators.
    (D) Select for employee use:
    (1) Air-purifying respirators that have a combination HEPA filter 
with an appropriate gas-sorbent cartridge or canister when the 
employee's exposure exceeds the permissible exposure level for 
inorganic arsenic and the relevant limit for other gases.
    (2) Front- or back-mounted gas masks equipped with HEPA filters and 
acid-gas canisters or any full-facepiece supplied-air respirators when 
the inorganic arsenic concentration is at or below 500 [mu]g/m\3\; and 
half-mask air-purifying respirators equipped with HEPA filters and 
acid-gas cartridges when the inorganic arsenic concentration is at or 
below 100 [mu]g/m\3\.
* * * * *
    7. In Sec.  1910.1025, remove Table II in paragraph (f)(2)(ii) and 
revise paragraphs (f)(3)(i) and (f)(3)(ii) to read as follows:


Sec.  1910.1025  Lead.

* * * * *
    (f) * * *
    (3) * * *(i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (B) Provide employees with full-facepiece respirators instead of 
half-mask respirators for protection against lead aerosols that cause 
eye or skin irritation at the use concentrations.
    (C) Provide HEPA filters for air-purifying respirators.
    (ii) Employers must provide employees with a powered air-purifying 
respirator (PAPR) instead of a negative-pressure respirator selected 
according to paragraph (f)(3)(i) of this standard when an employee 
chooses to use a PAPR and it provides adequate protection to the 
employee as specified by paragraph (f)(3)(i) of this standard.
* * * * * .
    8. In Sec.  1910.1027, remove Table 2 in paragraph (g)(3)(i) and 
revise paragraph (g)(3)(i) to read as follows:


Sec.  1910.1027  Cadmium.

* * * * *
    (g) * * *
    (3) * * *(i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (B) Provide employees with full-facepiece respirators when they 
experience eye irritation.
    (C) Provide HEPA filters for air-purifying respirators.
* * * * *
    9. In Sec.  1910.1028, remove Table 1 in paragraph (g)(3)(ii) and 
revise paragraphs (g)(2)(i) and (g)(3)(i) to read as follows:


Sec.  1910.1028  Benzene.

* * * * *
    (g) * * *
    (2) * * *
    (i) Employers must implement a respiratory protection program in 
accordance with 29 CFR 1910.134 (b) through (d) (except (d)(1)(iii)), 
and (f) through (m).
* * * * *
    (3) * * *
    (i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (B) Provide employees with any organic-vapor gas mask or any self-
contained breathing apparatus with a full facepiece to use for escape.
    (C) Use an organic-vapor cartridge or canister air-purifying 
respirators, and a chin-style canister with full-facepiece gas masks.
    (D) Ensure that canisters used with nonpowered air-purifying 
respirators have a minimum service life of four hours when tested at 
150 ppm benzene at a flow rate of 64 liters per minute (LPM), a 
temperature of 25[deg] C, and a relative humidity of 85%; for canisters 
used with tight-fitting or loose-fitting, powered air-purifying 
respirators, the flow rates for testing must be 115 LPM and 170 LPM, 
respectively.
* * * * *
    10. In Sec.  1910.1029, remove Table I in paragraph (g)(3) and 
revise paragraph (g)(3) to read as follows:


Sec.  1910.1029  Coke oven emissions.

* * * * *
    (g) * * *
    (3) Respirator selection. Employers must select, and provide to 
employees, the appropriate respirators specified in paragraph 
(d)(3)(i)(A) of 29 CFR 1910.134; however, employers must not select or 
use filtering facepieces for protection against coke oven emissions.
* * * * *
    11. In Sec.  1910.1043, remove Table I in paragraph (f)(3)(i) and 
revise paragraphs (f)(3)(i) and (f)(3)(ii) to read as follows:


Sec.  1910.1043  Cotton dust.

* * * * *
    (f) * * *
    (3) * * *
    (i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however, 
employers must not select or use filtering facepieces for protection 
against cotton dust concentrations greater than five times (5 X) the 
PEL.
    (B) Provide HEPA filters for air-purifying respirators used at 
cotton dust concentrations greater than ten times (10 X) the PEL.
    (ii) Employers must provide an employee with a powered air-
purifying respirator (PAPR) instead of a nonpowered air-purifying 
respirator selected according to paragraph (f)(3)(i) of this standard 
when the employee chooses to use a PAPR and it provides adequate 
protection to the employee as specified by paragraph (f)(3)(i) of this 
standard.
* * * * *
    12. In Sec.  1910.1044, remove Table 1 in paragraph (h)(3) and 
revise paragraph (h)(3) to read as follows:


Sec.  1910.1044  1,2-Dibromo-3-chloropropane.

* * * * *
    (h) * * *
    (3) Respirator selection. Employers must:
    (i) Select, and provide to employees, the appropriate atmosphere-
supplying respirator specified in paragraph (d)(3)(i)(A) of 29 CFR 
1910.134.
    (ii) Provide employees with one of the following respirator options 
to use for entry into, or escape from, unknown DBCP concentrations:
    (A) A combination respirator that includes a supplied-air 
respirator with a full facepiece operated in a pressure-demand or other 
positive-pressure or continuous-flow mode, as well as an auxiliary 
self-contained breathing apparatus (SCBA) operated in a pressure-demand 
or positive-pressure mode.
    (B) An SCBA with a full facepiece operated in a pressure-demand or 
other positive-pressure mode.
* * * * *
    13. In Sec.  1910.1045, remove Table I in paragraph (h)(3) and 
revise paragraphs (h)(2)(i) and (h)(3) to read as follows:

[[Page 34117]]

Sec.  1910.1045  Acrylonitrile.

* * * * *
    (h) * * *
    (2) * * *
    (i) Employers must implement a respiratory protection program in 
accordance with 29 CFR 1910.134 (b) through (d) (except (d)(1)(iii)), 
and (f) through (m).
* * * * *
    (3) Respirator selection. Employers must:
    (i) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (ii) For escape, provide employees with any organic-vapor 
respirator or any self-contained breathing apparatus permitted for use 
under paragraph (h)(3)(i) of this standard.
* * * * *
    14. In Sec.  1910.1047, remove Table 1 in paragraph (g)(3) and 
revise paragraph (g)(3) to read as follows:


Sec.  1910.1047  Ethylene oxide.

* * * * *
    (g) * * *
    (3) Respirator selection. Employers must:
    (i) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however, 
employers must not select or use half-masks of any type because EtO may 
cause eye irritation or injury.
    (ii) Equip each air-purifying, full facepiece respirator with a 
front- or back-mounted canister approved for protection against 
ethylene oxide.
    (iii) For escape, provide employees with any respirator permitted 
for use under paragraph (g)(3)(i) of this standard.
* * * * *
    15. In Sec.  1910.1048, remove Table 1 in paragraph (g)(3)(i) and 
revise paragraphs (g)(2) and (g)(3) to read as follows:


Sec.  1910.1048  Formaldehyde.

* * * * *
    (g) * * *
    (2) Respirator programs. (i) Employers must implement a respiratory 
protection program in accordance with 29 CFR 1910.134 (b) through (d) 
(except (d)(1)(iii)), and (f) through (m).
    (ii) If employees use air-purifying respirators with chemical 
cartridges or canisters that do not contain end-of-service-life 
indicators approved by the National Institute for Occupational Safety 
and Health, employers must replace these cartridges or canisters as 
specified by paragraphs (d)(3)(iii)(B)(1) and (B)(2) of 29 CFR 
1910.134, or at the end of the workshift, whichever condition occurs 
first.
    (3) Respirator selection. (i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (B) Equip each air-purifying, full facepiece respirator with a 
canister or cartridge approved for protection against formaldehyde.
    (C) For escape, provide employees with one of the following 
respirator options: A self-contained breathing apparatus operated in 
the demand or pressure-demand mode; or a full facepiece respirator 
having a chin-style, or a front- or back-mounted industrial-size, 
canister or cartridge approved for protection against formaldehyde.
    (ii) Employers may substitute an air-purifying, half-mask 
respirator for an air-purifying, full facepiece respirator if they 
equip the half-mask respirator with a cartridge approved for protection 
against formaldehyde and provide the affected employee with effective 
gas-proof goggles.
    (iii) Employers must provide employees who have difficulty using 
negative-pressure respirators with powered air-purifying respirators 
permitted for use under paragraph (g)(3)(i)(A) of this standard and 
that provide adequate protection against their formaldehyde exposures.
* * * * *
    16. In Sec.  1910.1050, remove Table 1 in paragraph (h)(3)(i) and 
revise paragraph (h)(3)(i) to read as follows:


Sec.  1910.1050  Methylenedianiline.

* * * * *
    (h) * * *
    (3) * * *
    (i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (B) Provide HEPA filters for air-purifying respirators.
    (C) For escape, provide employees with one of the following 
respirator options: Any self-contained breathing apparatus with a full 
facepiece or hood operated in the positive-pressure or continuous-flow 
mode; or a full-facepiece, air-purifying respirator.
    (D) Provide a combination HEPA filter and organic-vapor canister or 
cartridge with air-purifying respirators when MDA is in liquid form or 
part of a process requiring heat.
* * * * *
    17. In Sec.  1910.1052, remove Table 2 in paragraph (g)(3) and 
revise paragraph (g)(3) to read as follows:


Sec.  1910.1052  Methylene chloride.

* * * * *
    (g) * * *
    (3) Respirator selection. Employers must:
    (i) Select, and provide to employees, the appropriate atmosphere-
supplying respirator specified in paragraph (d)(3)(i)(A) of 29 CFR 
1910.134; however, employers must not select or use half-masks of any 
type because MC may cause eye irritation or damage.
    (ii) For emergency escape, provide employees with one of the 
following respirator options: A self-contained breathing apparatus 
operated in the continuous-flow or pressure-demand; or a gas mask with 
an organic-vapor canister.
* * * * *

PART 1915--[AMENDED]

    18. The authority citation for part 1915 is revised to read as 
follows:

    Authority: Section 41, Longshore and Harbor Workers' 
Compensation Act (33 U.S.C. 941); Sections 4, 6, and 8 of the 
Occupational Safety and Health Act of 1970 (20 U.S.C. 653, 655, and 
687); and Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76 
(41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 
111), or 3-2000 (62 FR 50017).

    Sections 1915.120 and 1915.152 also issued under 29 CFR 1911.

Subpart Z--[Amended]

    19. In Sec.  1915.1001, remove Table 1 in paragraph (h)(2)(iii) and 
revise paragraph (h)(2) to read as follows:


Sec.  1915.1001  Asbestos.

* * * * *
    (h) * * *
    (2) Respirator selection. (i) Employers must select, and provide to 
employees at no cost, the appropriate respirators specified in 
paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however, employers must not 
select or use filtering-facepiece respirators for use against asbestos 
fibers.
    (ii) Employers are to provide HEPA filters for air-purifying 
respirators.
    (iii) Employers must:
    (A) Inform employees that they may require the employer to provide 
a tight-fitting, powered air-purifying respirator (PAPR) permitted for 
use under paragraph (h)(2)(i) of this standard instead of a negative-
pressure respirator.
    (B) Provide employees with a tight-fitting PAPR instead of a 
negative-pressure respirator when the employees choose to use a tight-
fitting PAPR and it provides them with the required protection against 
asbestos.
    (iv) Employers must provide employees with an air-purifying, half-

[[Page 34118]]

mask respirator, other than a filtering-facepiece respirator, whenever 
the employees perform:
    (A) Class II or Class III asbestos work for which no negative-
exposure assessment is available.
    (B) Class III asbestos work involving disturbance of TSI or 
surfacing ACM or PACM.
    (v) Employers must provide employees with:
    (A) A tight-fitting, powered air-purifying respirator or a full-
facepiece, supplied-air respirator operated in the pressure-demand mode 
and equipped with either HEPA egress cartridges or an auxiliary 
positive-pressure, self-contained breathing apparatus (SCBA) whenever 
the employees are in a regulated area performing Class I asbestos work 
for which a negative-exposure assessment is not available and the 
exposure assessment indicates that the exposure level will be at or 
below 1 f/cc as an 8-hour time-weighted average (TWA).
    (B) A full-facepiece, supplied-air respirator operated in the 
pressure-demand mode and equipped with an auxiliary positive-pressure 
SCBA whenever the employees are in a regulated area performing Class I 
asbestos work for which a negative-exposure assessment is not available 
and the exposure assessment indicates that the exposure level will be 
above 1 f/cc as an 8-hour TWA.
* * * * *

PART 1926--[AMENDED]

Subpart D--[Amended]

    20. The authority citation for subpart D of part 1926 is revised to 
read as follows:

    Authority: Section 107, Contract Work Hours and Safety Standards 
Act (Construction Safety Act) (40 U.S.C. 333); sections 4, 6, and 8 
of the Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 
655, and 657); Secretary of Labor's Orders 12-71 (36 FR 8754), 8-76 
(41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 
111), or 3-2000 (62 FR 50017); and 29 CFR part 11.
    Sections 1926.58, 1926.59, 1926.60, and 1926.65 also issued 
under 5 U.S.C. 553 and 29 CFR part 1911.
    Section 1926.62 also issued under section 1031 of the Housing 
and Community Development Act of 1992 (42 U.S.C. 4853).

    Section 1926.65 of 29 CFR also issued under section 126 of the 
Superfund Amendments and Reauthorization Act of 1986, as amended (29 
U.S.C. 655 note), and 5 U.S.C. 553.
    21. In Sec.  1926.60, remove Table 1 and revise paragraph (i)(3)(i) 
to read as follows:


Sec.  1926.60  Methylenedianiline.

* * * * *
    (i) * * *
    (3) * * *
    (i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (B) Provide HEPA filters for air-purifying respirators.
    (C) For escape, provide employees with one of the following 
respirator options: Any self-contained breathing apparatus with a full 
facepiece or hood operated in the positive-pressure or continuous-flow 
mode; or a full-facepiece, air-purifying respirator.
    (D) Provide a combination HEPA filter and organic-vapor canister or 
cartridge with air-purifying respirators when MDA is in liquid form or 
part of a process requiring heat.
* * * * *
    22. In Sec.  1926.62, remove Table 1 in paragraph (f)(3) and revise 
paragraph (f)(3)(i) to read as follows:


Sec.  1926.62  Lead.

* * * * *
    (f) * * *
    (3) * * *
    (i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (B) Provide employees with a full-facepiece respirator instead of a 
half-mask respirator for protection against lead aerosols that cause 
eye or skin irritation at the use concentrations.
    (C) Provide HEPA filters for air-purifying respirators.
* * * * *

Subpart Z--[Amended]

    23. The authority citation for subpart Z of part 1926 is revised to 
read as follows:

    Authority: Sections 4, 6, and 8 of the Occupational Safety and 
Health Act of 1970 (29 U.S.C. 653, 655, 657); Secretary of Labor's 
Orders 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR 35736), 
1-90 (55 FR 9033), 6-96 (62 FR 111), or 3-2000 (62 FR 50017); and 29 
CFR part 11.
    Section 1926.1102 not issued under 29 U.S.C. 655 or 29 CFR part 
1911; also issued under 5 U.S.C. 553.

    24. In Sec.  1926.1101, remove Table 1 in paragraph (h)(3)(i) and 
revise paragraph (h)(3) to read as follows:


Sec.  1926.1101  Asbestos.

* * * * *
    (h) * * *
    (3) Respirator selection. (i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however, 
employers must not select or use filtering-facepiece respirators for 
use against asbestos fibers.
    (B) Provide HEPA filters for air-purifying respirators.
    (ii) Employers must provide an employee with tight-fitting, powered 
air-purifying respirator (PAPR) instead of a negative-pressure 
respirator selected according to paragraph (h)(3)(i)(A) of this 
standard when the employee chooses to use a PAPR and it provides 
adequate protection to the employee.
    (iii) Employers must provide employees with an air-purifying, half-
mask respirator, other than a filtering-facepiece respirator, whenever 
the employees perform:
    (A) Class II or Class III asbestos work for which no negative-
exposure assessment is available.
    (B) Class III asbestos work involving disturbance of TSI or 
surfacing ACM or PACM.
    (iv) Employers must provide employees with:
    (A) A tight-fitting, powered air-purifying respirator or a full-
facepiece, supplied-air respirator operated in the pressure-demand mode 
and equipped with either HEPA egress cartridges or an auxiliary 
positive-pressure, self-contained breathing apparatus (SCBA) whenever 
the employees are in a regulated area performing Class I asbestos work 
for which a negative-exposure assessment is not available and the 
exposure assessment indicates that the exposure level will be at or 
below 1 f/cc as an 8-hour time-weighted average (TWA).
    (B) A full-facepiece, supplied-air respirator operated in the 
pressure-demand mode and equipped with an auxiliary positive-pressure 
SCBA whenever the employees are in a regulated area performing Class I 
asbestos work for which a negative-exposure assessment is not available 
and the exposure assessment indicates that the exposure level will be 
above 1 f/cc as an 8-hour TWA.
* * * * *
    25. In Sec.  1926.1127, remove Table 1 in paragraph (g)(3)(i) and 
revise paragraph (g)(3)(i) to read as follows:


Sec.  1926.1127  Cadmium.

* * * * *
    (g) * * *
    (3) * * *
    (i) Employers must:
    (A) Select, and provide to employees, the appropriate respirators 
specified in

[[Page 34119]]

paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
    (B) Provide employees with full-facepiece respirators when they 
experience eye irritation.
    (C) Provide HEPA filters for air-purifying respirators.
* * * * *
[FR Doc. 03-13749 Filed 6-5-03; 8:45 am]
BILLING CODE 4510-26-P