[Federal Register Volume 62, Number 211 (Friday, October 31, 1997)]
[Notices]
[Pages 58995-59002]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-28930]


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DEPARTMENT OF LABOR

Occupational Safety and Health Administration
[V-97-1]


Notice of Application for Permanent Variance From Dixie Divers

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

ACTION: Notice of application for permanent variance from Dixie Divers.

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SUMMARY: This notice announces the application of Dixie Divers, Inc., 
for a permanent variance from the Occupational Safety and Health 
Administration (OSHA) requirements for the availability and use of 
decompression chambers for mixed-gas diving operations (i.e., 29 CFR 
1910.423(b)(2), 29 CFR 1910.423 (c)(3)(iii), and 29 CFR 
1910.426(b)(1)).

DATES: The last date for interested parties to submit comments on the 
variance application is December 30, 1997. The last date for affected 
parties, including employers and employees, to request a hearing 
regarding the variance application is December 30, 1997.

ADDRESSES: The original and four copies of written comments and 
requests for a hearing must be submitted to: U.S. Department of Labor, 
Occupational Safety and Health Administration, Office of Variance 
Determination, Room N-3653, Attention: Ms. Juanita Jones, 200 
Constitution Avenue, N.W., Washington, D.C. 20210.
    For comments, one original (hardcopy) and one diskette (5\1/4\-or 
3\1/2\-inch) in Wordperfect 5.0, 5.1. or 6.1, or ASCII may be sent to 
this address; however, any information not contained on the diskettes 
(e.g., studies, articles) must be submitted in quadruplicate with the 
original written comments. Written comments of 10 pages or less may be 
transmitted by facsimile (fax) to OSHA's office of Variance 
Determination at (202) 219-7068, provided the original and four copies 
of the fax material are sent to OSHA's Office of Variance Determination 
within the 60day period allowed for comments.

FOR FURTHER INFORMATION CONTACT:
Ms. Juanita Jones, Office of Variance Determination (see ADDRESSES 
above), Telephone: (202) 219-7193, Fax: (202) 219-7068, E-mail: 
[email protected]

or the following Regional and Area Offices:

U.S. Department of Labor--OSHA, 1375 Peachtree Street, N.E., Suite 587, 
Atlanta, Georgia 30367, Telephone: (404) 562-2300, Fax: (404) 562-2295, 
E-mail: [email protected] and
U.S. Department of Labor--OSHA, 5807 Breckenridge Parkway, Suite A, 
Tampa, Florida 33610, Telephone: (813) 626-1177, Fax: (813) 626-7015, 
E-mail: [email protected].

    For an electronic copy of this Federal Register notice, contact the 
Labor News Bulletin Board at (202) 219-4748, or access OSHA's web page 
on the Internet at http://www.OSHA.gov.

Notice of Application

    Dixie Divers, Inc. (hereafter, ``Dixie,'' ``applicant,'' or 
``employer''), 14601 Orange Avenue, Ft. Pierce, Florida 34945, has 
applied, pursuant to Section 6(d) of the Occupational Safety and Health 
Act of 1970 (29 U.S.C. 655) and 29 CFR 1905.11, for a permanent 
variance from the requirements specified in 29 CFR 1910.423(b)(2), 29 
CFR 1910.423(c)(3)(iii), and 29 CFR 1910.426(b)(1) concerning the 
availability and use of decompression chambers during mixed-gas diving 
operations.

SUPPLEMENTARY INFORMATION:

I. Background

    The addresses of the places of employment affected by this 
application for a permanent variance are diving training facilities 
operated by Dixie Divers, including:

Dixie Divers of Boca Raton, 8241 Glades Road, Boca Raton, Florida 33434
Dixie Divers of Boynton Beach, 340 North Congress, Boynton Beach, 
Florida 33426
Dixie Divers of Coral Springs, 2060 University Drive, Coral Springs, 
Florida 33071
Dixie Divers of Deerfield, 1645 Southeast 3rd Court, Deerfield Beach, 
Florida 33441
Dixie Divers of Fort Pierce, 1717 South U.S. Route 1, Fort Pierce, 
Florida 34950
Dixie Divers of Key Largo, 103400 Overseas Highway, Key Largo, Florida 
33037
Dixie Divers of Lakeland, 4120 South Florida Avenue, Lakeland, Florida 
33813

[[Page 58996]]

Dixie Divers of Palm Bay, 4651 Babcock Street, Northeast, Palm Bay, 
Florida 32905
Dixie Divers of Panama City, 109B West 23rd Street, Panama City, 
Florida 32405
Dixie Divers of Stuart, 1839 Southeast Federal Highway, Stuart, Florida 
34994
Dixie Divers of Vero Beach, 1833 U.S. Route 1, Vero Beach, Florida 
32960
Dixie Divers of West Palm Beach, 1401 South Military Trail, West Palm 
Beach, Florida 33415.

    The applicant has certified that employees who would be affected by 
the permanent variance have been notified of the application for a 
permanent variance by posting a copy of the application at locations 
where employee notices are normally posted, and that the employees have 
been informed of their right to petition the Assistant Secretary of 
Labor for the Occupational Safety and Health Administration for a 
hearing on the application.
    Regarding the merits of the application, the applicant states that 
it is providing a place of employment at least as safe and healthful as 
that required by 29 CFR 1910.423(b)(2), 1910.423(c)(3)(iii), and 29 CFR 
1910.426(b)(1).
    Paragraph (b)(2) of 29 CFR 1910.423 requires that:

    For any dive outside the no-decompression limits, deeper than 
100 fsw [feet of sea water], or using mixed gas as a breathing 
mixture, the employer shall instruct the diver to remain awake and 
in the vicinity of the decompression chamber which is at the dive 
location for at least one hour after the dive (including 
decompression or treatment as appropriate).
    Paragraph (c)(3)(iii) of 29 CFR 1910.423 specifies that:
    [The decompression chamber shall be] located within 5 minutes of 
the dive location.
    Paragraph (b)(1) of 29 CFR 1910.426 requires that:
    A decompression chamber is ready for use at the dive location.

    The purpose of these standards is to provide for the rapid 
treatment of decompression sickness (DCS) that may result from 
breathing mixed gases at diving depths and durations that require 
decompression.
    The applicant operates 12 diving schools; five of the schools are 
operated directly by the applicant and seven of the schools are 
franchise operations. The applicant employs 34 recreational diving 
instructors, who are highly skilled and experienced divers, to train 
novice divers in recreational diving knowledge and skills. The same 34 
employees also serve as diving guides and lead groups of sports divers 
to local diving sites for recreational purposes. (The recreational 
diving instructors and diving guides are also referred to hereafter as 
``employees'' or, more generally, as ``divers.'')
    As recreational diving instructors, employees train recreational 
diving students in conventional diving procedures and the safe 
operation of diving equipment. The diving students may use an open-
circuit, semi-closed-circuit, or closed-circuit self-contained 
underwater breathing apparatus (SCUBA) with compressed-air or a high-
oxygen breathing-gas mixture during these training dives. The 
applicant's training program involves both classroom instruction and 
practice dives in which the employees accompany diving students to 
ocean depths of zero to 130 feet of sea water (fsw) for durations that 
do not exceed established no-decompression limits. During these 
training dives, the diving instructors provide underwater instruction 
in, and allow the diving students to practice using, diving procedures 
and equipment. A diving instructor may make as many as three to four 
training dives a day while training diving students either individually 
or in small groups.
    As diving guides, employees lead small groups of trained sports 
divers to local undersea diving locations for recreaitonal purposes. 
The diving locations are pre-selected by the diving guide. The diving 
guide provides the sports divers with information regarding the diving 
site, including hazardous conditions and safe practices. The 
recreational diving groups consist of sports divers who use open-
circuit, semi-closed-circuit, or closed-circuit SCUBA with compressed-
air or a high-oxygen breathing-gas mixture while diving. In conducting 
these diving excursions, the diving guide will dive for periods that do 
not exceed established no-decompression limits at diving depths ranging 
from zero to 130 fsw. A diving guide may make as many as five of these 
recreational diving excursions a day.
    The applicant proposes to have its employees use open-circuit, 
closed-circuit, or semi-closed-circuit SCUBA supplied with high-oxygen 
breathing-gas mixtures that contain a higher fraction of oxygen than 
air. For the purpose of this application, the term ``high-oxygen 
breathing-gas mixture'' refers to any breathing-gas mixture containing 
an oxygen fraction of more that 22 percent (22%) by volume; the maximum 
oxygen fraction is 40 percent (40%) by volume for open-circuit SCUBA, 
and never exceeds an oxygen partial pressure delivered to the diver of 
1.40 ATA (atmospheres absolute) for any SCUBA.
    The high-oxygen breathing-gas mixture is obtained by mixing pure 
nitrogen with pure oxygen, removing oxygen from air for mixing with 
pure nitrogen, adding pure oxygen to air, or by denitrogenating air. 
Employees who use high-oxygen breathing-gas mixtures will be able to 
make more or longer repetitive-training and/or excursion divers than 
they would using compressed-air open-circuit SCUBA (their current mode 
of operation) because the higher oxygen and lower nitrogen levels of 
these breathing-gas mixtures will extend the no-decompression limits of 
these dives compared to repetitive-training and/or excursion dives made 
using breathing gases composed only of air. The use of closed-circuit 
and semi-closed-circuit SCUBA will also enable employees to make 
repetitive-training and/or excursion dives without continually 
refilling the cylinders that contain the breathing-gas mixture, as is 
the case currently when open-circuit SCUBA is used.
    According to the applicant, the employees covered by this variance 
application will receive a level of protection that is equal to, or 
greater than, the level of protection they receive when they use 
compressed air supplied to open-circuit SCUBAs under no-decompression 
diving limits as permitted by the exemption to the Commercial Diving 
Operations standard at 29 CFR 1910.401(a)(2)(i).
    Since OSHA first published the Commercial Diving Operations 
standard in 1977, diving equipment (including dive-decompression 
computers), decompression tables, training, and safety programs have 
steadily improved. Consequently, the overall safety performance of 
recreational diving has improved substantially. According to the data 
discussed in Reference A, the fatality rate for recreational diving as 
a whole (including non-work, recreational diving) has fallen from 8.62 
fatalities per 100,000 divers in 1976 to 2.09-2.68 fatalities per 
100,000 divers in 1991.
    In the preamble to the Commercial Diving Operations standard (42 FR 
37650), OSHA noted that high-oxygen breathing-gas mixtures were being 
developed by the National Oceanic and Atmospheric Administration 
(NOAA), but had not yet (in 1977) been made available to the 
recreational diving community. This technology increases the fraction 
of oxygen contained in the breathing-gas mixture, thereby exposing 
divers using this breathing-gas mixture to a decreased fraction of 
nitrogen.

[[Page 58997]]

During the 1980s, NOAA published diving procedures, including 
decompression protocols, for dives using high-oxygen breathing-gas 
mixtures. (See Reference B.)
    While the percentage of oxygen in breathable air is 19.5-22.0 (see 
Gas Association Commodity Specification G-7.1-1966), the percentage of 
oxygen in high-oxygen breathing-gas mixtures for open-circuit SCUBA 
typically ranges from 28 to 40. By increasing the fraction of oxygen in 
the breathing-gas mixture, the driver's bodily tissues accumulate less 
nitrogen during a dive. As a result, the mathematical probability of 
developing decompression sickness (DCS) is reduced compared to divers 
who use compressed air under the same diving conditions (i.e., depth, 
bottom time, and descent and ascent rates). (See Reference C.)
    Regardless of the diving equipment used (e.g., open-circuit SCUBA, 
surface-supplied air), paragraph 29 CFR 1910.423(b)(2), 29 CFR 
1910.423(c)(3)(iii), and 29 CFR 1910.426(b)(1) of OSHA's Commercial 
Diving Operations standard require a decompression chamber at the 
diving site if a diver is supplied with high-oxygen breathing-gas 
mixtures; these requirements apply even if the dive does not involve 
decompression stops (i.e., is a no-decompression dive). Dixie believes, 
however, that the reduced mathematical probability of DCS that results 
from the use of high-oxygen breathing-gas mixtures under the conditions 
specified in this variance application will provide a level of safety 
to its employees that is equivalent to the level of safety they 
experience when they use open-circuit, compressed-air SCUBA within the 
no-decompression limits. Dixie asserts, therefore, that maintaining a 
decompression chamber at the dive location should not be required if it 
complies with the alternative conditions specified in this variance 
application.

II. Proposed Alternative

    Instead of complying with the standard, the applicant contends that 
the specific safety procedures and technical provisions set forth in 
the variance application make the need for immediate access to a 
decompression chamber no greater than would be in the case when its 
divers use open-circuit, compressed-air SCUBA within the no-
decompression diving limits as specified in the exemption to the 
Commercial Diving Operations standard under the provisions of 29 CFR 
1910.401(a)(2)(i). These procedures and provisions are described in 
each of the following conditions:
    A. High-oxygen breathing-gas mixtures shall be supplied using open-
circuit, closed-circuit, or semi-closed-circuit SCUBA. If the divers 
use a closed-circuit or semi-closed-circuit SCUBA, this diving 
equipment must use:
    1. Commercially-available disposable scrubber cartridges prepacked 
with sorbents that remove carbon dioxide and maintain the carbon-
dioxide level in the breathable gas (i.e., the gas being inhaled 
directly by the diver from the regulator) below a partial pressure of 
0.1 ATA. An alternate scrubber method may be used provided the employer 
demonstrates that this method is equal in effectiveness to 
commercially-available disposable scrubber cartridges in removing 
carbon dioxide and maintaining the carbon-dioxide level in the 
breathable gas below a partial pressure of 0.1 ATA.
    2. Redundant, continuously-functioning carbon-dioxide sensor, 
moisture traps, an over-pressure valve, and redundant, continuously-
functioning moisture sensors, or an equivalent method that provides 
immediate and accurate detection of depleted scrubber sorbent or 
scrubber sorbent that has been compromised by moisture contamination.
    3. Flexible breathing bags (i.e., ``counter lungs'').
    4. An open-circuit (``bail-out'') system in which the second stage 
of the SCUBA regulator is connected to a separate supply of emergency 
breathing gas, or for semi-closed-circuit and closed-circuit SCUBA, a 
diluent supply of emergency breathing gas, in the event the SCUBA 
malfunctions (e.g., fails to provide a breathable oxygen level or to 
maintain carbon dioxide below 0.1 ATA). The bail-out system shall be at 
least as reliable as other commercially-available open-circuit SCUBA, 
and contain a supply of breathable air or a high-oxygen breathing-gas 
mixture sufficient to last 3 to 4 minutes at 130 fsw.
    5. An information module that provides:
    a. For closed-circuit SCUBA, digital and/or graphical displays for: 
gas pressures (including oxygen partial pressures) and/or deviations 
from the preset values for this information; time (i.e., surface time, 
dive time remaining, required ceiling stop times, and total ascent 
time); depth (i.e., current depth, maximum depth achieved, and required 
ceiling stop depth); gas temperature within the breathing loop; and 
ascent and decent rates.
    b. For semi-closed circuit SCUBA, analog and/or digital displays 
for: gas pressures; time (i.e., surface time, dive time remaining, 
required ceiling stop times, and total ascent time); and ascent and 
decent rates.
    c. For both closed-circuit and semi-closed-circuit SCUBA, flashing 
displays and symbols in the data-display module, audible alarms, or 
visual displays in the mask sufficient to warn the diver of: solenoid 
failure (when solenoids are used); low battery voltage (for electronic 
instruments); excessive ascent and descent rates; depth levels that are 
shallower than the required ceiling stop depth; and, for closed-circuit 
SCUBA only, oxygen partial pressures that are below or exceed the 
planned oxygen levels (e.g., exceed an oxygen partial pressure 
delivered to the diver of 1.40 ATA).
    B. Closed-circuit SCUBA also must use:
    1. Oxygen and diluent gas (i.e., air or nitrogen) supply-pressure 
sensors, depth sensors, continuously-functioning and redundant 
temperature-compensated oxygen sensors, and continuously-functioning 
gas-loop and ambient water-temperature sensors.
    2. A gas-controller package with electrically-operated solenoid 
oxygen-supply valves and a pressure-activated regulator with a second-
stage diluent-gas addition valve.
    3. A manually-operated, gas-supply bypass valve to add oxygen or 
diluent gas to the breathing loop.
    4. Separate oxygen and diluent-gas cylinders to supply the 
breathing-gas mixture.
    C. Regardless of the SCUBA used (i.e., open-circuit, closed-
circuit, or semi-closed-circuit), the fraction of oxygen in the high-
oxygen breathing-gas mixture shall be greater than the fraction of 
oxygen in compressed air, with a maximum fraction of breathable oxygen 
of 40 percent (40%) by volume for open-circuit SCUBA, but never to 
exceed a maximum oxygen partial pressure delivered to the diver of 1.40 
ATA for any SCUBA.
    D. Regardless of the SCUBA used, the diver shall dive no deeper 
than 130 fsw. or to a maximum oxygen partial pressure delivered to the 
diver of 1.40 ATA, whichever is most restrictive.
    E. The employer shall ensure that the divers' exposures to partial 
pressures of oxygen between 0.60 and 1.40 ATA (delivered to the diver) 
do not exceed the 24-hour single-exposure time limits specified by the 
1991 NOAA Diving Manual or other oxygen-exposure limits, such as the 
Diving Science and Technology (DSAT) Oxygen Exposure Table, that 
provide a level of oxygen-toxicity protection at least equivalent to 
the level of protection afforded by the 1991 NOAA Diving Manual. (See

[[Page 58998]]

Reference D.) In using these tables, time limits shall be determined as 
the function of the maximum partial pressure of oxygen to which the 
diver was exposed during the dive, as well as the total time of the 
dive (i.e., from the time the diver leaves the surface until that diver 
returns to the surface), not the total bottom time of the dive.
    F. Nitrogen shall be the only inert gas used to obtain the 
breathing-gas mixture.
    G. The conditions listed below apply to mixing and analyzing the 
high-oxygen breathing-gas mixtures:
    1. If the breathable gas is a high-oxygen mixture compounded by the 
employer, the follow procedures apply:
    a. Either the continuous-flow or partial-pressure mixing techniques 
specified in the 1991 NOAA Diving Manual or a semi-permeable membrane 
shall be used to compound the appropriate breathing gas prior to 
delivery to the SCUBA cylinders.
    b. For open-circuit and semi-closed-circuit SCUBA , the oxygen 
fraction of the breathing-gas mixture must be analyzed by the employer 
using a oxygen analyzer (e.g., consisting of a fuel-cell process the 
oxidizes a chemical to produce an electrical output proportional to the 
oxygen content) that is accurate to within one percent (1%) by volume.
    c. For closed-circuit SCUBA, the oxygen fraction used in the 
breathing loop must be analyzed by the employer to an accuracy within 
one percent (1%) by using redundant temperature-compensated 
electromechanical sensors (e.g., consisting of electrodes that absorb 
oxygen that is used to form ions that react with counter electrodes and 
produce electrical outputs proportional to the oxygen fraction).
    d. The accuracy of the equipment used by the employer to analyze 
the oxygen fraction shall be maintained in accordance with the 
manufacturer's instructions.
    2. If the breathable gas is procured (purchased) high-oxygen 
breathing-gas mixture, the employer must ensure that:
    a. The commercial supplier of the gas mixture analyses and 
documents the oxygen fraction of the mixture, and uses an oxygen-
analytic method at least as accurate and reliable as the methods 
specified in Condition G.1 above;
    b. The commercial supplier provides certification of the oxygen 
analysis; and
    c. The oxygen used in the high-oxygen breathing-gas shall be Grade 
A (aviator's oxygen) or Grade B (Industrial/medical oxygen), and shall 
meet the specifications, including the purity requirements, found in 
the 1991 NOAA Diving Manual. These specifications shall be analyzed 
using a method at least as accurate and reliable as the method 
described under Condition G.1 above, and the employer must obtain from 
the commercial supplier of the breathing-gas mixture a certification 
document to this effect.
    H. If the employer uses a compressor to produce the high-oxygen 
breathing-gas mixture, the compressor shall be oil-less or the 
compressed-air shall be filtered to produce oxygen-compatible air.
    I. SCUBA exposed to high-pressure (i.e., exceeding 300 psi) high-
oxygen breathing-gas mixtures and/or pure oxygen must be rated for 
oxygen service (i.e., use components that are oxygen compatible and 
oxygen clean).
    J. For both single and repetitive diving conducted while using a 
high-oxygen breathing-gas mixture, the diver shall remain within the 
no-decompression limits specified for such diving. The no-decompression 
limits shall be determined from decompression tables and formulas 
developed for single and repetitive air diving and published in the 
1991 NOAA Diving Manual. The employer may use other decompression 
tables, formulas, and/or principles for their purpose provided the 
employer demonstrates that these tables, formulas, and/or principles 
are equivalent to, or better than, the NOAA tables and formulas.
    K. The employee may wear and use an underwater dive-decompression 
computer designed to regulate decompression procedures provided that:
    1. The dive-decompression computer uses decompression procedures 
that are based on the no-decompression tables or formulas specified in 
Condition J above;
    2. The output from the dive-decompression computer can be 
demonstrated by the employer to provide its divers with protection that 
is equivalent to the tables or formulas specified in Condition J above;
    3. A log is maintained at the dive site that records, for each 
dive, ``Left Surface Time,'' ``Reached Surface Time,'' ``Maximum 
Depth,'' ``Manufacturer and Model Number of the Dive-Decompression 
Computer,'' and ``Serial Number of Dive-Decompression Computer''; and
    4. Decompression tables are available at the dive site for use in 
case the dive-decompression computer fails, is damaged, or is lost.
    L. Regardless of the SCUBA used, the employer shall confirm prior 
to each day's diving operations in which a high-oxygen breathing-gas 
mixture is supplied by the diver's SCUBA that the following resources 
are available to treat a diving-related medical emergency (e.g., DCS, 
air embolism) that may occur to a diver who uses such a breathing-gas 
mixture:
    1. A hospital, qualified health-care professionals, and the nearest 
Coast Guard Coordination Center (or the State or Municipal equivalent), 
with a list of telephone or call numbers for these health-care 
professionals and facilities being maintained at the dive site; and
    2. If a decompression chamber is not at the dive site, access and 
transportation to a decompression chamber must be available, with the 
transportation being capable of delivering the diver having a diving-
related medical emergency to the decompression chamber within two hours 
of the injury.
    M. Portable oxygen equipment with a transparent mask shall be 
available at the dive site to treat the diver who has a diving-related 
medical emergency; the oxygen shall be available for administration to 
the diver during the entire period the diver is being transported to a 
decompression chamber.
    N. At least two personnel, one of whom shall be a diver employed by 
the applicant and both of whom are qualified in first-aid and in the 
administration of treatment oxygen, shall be available at the dive site 
to provide emergency treatment for diving-related medical emergencies.
    O. The employer shall ensure that the employees covered by this 
variance application are divers who are certified by a training agency 
recognized by the recreational diving industry and who perform the 
functions of recreational diving instructors or diving guides. The 
divers must be qualified by such an agency to use the SCUBA and high-
oxygen breathing-gas mixtures relevant to their recreational diving 
operations.
    P. The employer shall ensure that the divers covered by this 
variance application conform with the recreational diving practices 
specified in the instructor training manual currently used by the 
certified training agency with which the diver is affiliated, to the 
extent that these practices are consistent with the conditions 
specified above in this variance application.

III. Rationale for the Proposed Alternative

    The applicant provided a rationale for each of the conditions 
specified above in the proposed alternative; this section presents this 
rationale.

[[Page 58999]]

Conditions A and B

    These conditions allow the use of closed-circuit and semi-closed-
circuit SCUBA, in addition to traditional open-circuit SCUBA. While the 
safety of open-circuit SCUBA for use by recreational diving instructors 
is acknowledged by OSHA under the exemption provision to its Commercial 
Diving Operations standard at 29 CFR 1910.401(a)(2)(i), this provision 
made no reference to closed-circuit or semi-closed-circuit SCUBA 
because such equipment was not available or in common use by 
recreational diving instructors when OSHA's Commercial Diving 
Operations standard was promulgated in 1977. Closed-circuit and semi-
closed-circuit SCUBA is now available for use by recreational divers, 
although data related to the reliability and safety of such equipment 
are difficult to obtain because its use by recreational divers is still 
uncommon. Conditions A and B specify a number of technical features 
(including manually-operated ``bail-out'' systems) that will ensure 
that such SCUBA supplies and maintains the appropriate breathing-gas 
mixture to the divers, thereby providing them with a degree of safety 
that is at least as protective as they would obtain using compressed-
air, open-circuit SCUBA under no-decompression diving limits.
    Conditions A and B require closed-circuit and semi-closed-circuit 
SCUBA to operate so as to: automatically inject oxygen into the 
breathing loop to maintain an oxygen partial pressure in the breathable 
gas (i.e., delivered to the diver) of 0.95 to 1.40 ATA; automatically 
add diluent gas through the regulator to compensate for decreases in 
gas volume during descent; and permit these functions to be performed 
manually by the diver using gas-supply bypass valves provided on the 
equipment. These conditions will maintain oxygen levels in the 
breathable gas within the range of partial pressures specified by 
Condition E above, and will ensure that sufficient breathing-gas 
pressure is available to deliver breathable gas to the diver without 
adversely affecting the diver's breathing effort.
    These conditions also will prevent the diver from breathing unsafe 
levels of carbon dioxide by requiring the use of proven sorbent 
systems, continuously-functioning control systems, and information 
displays that inform the diver of the SCUBA's status. Should carbon 
dioxide in closed-circuit SCUBA exceed planned levels, a visual display 
and auditory warning will be activated so that the diver is alerted to 
take corrective action. Semi-closed-circuit SCUBA equipment shall 
provide the diver with an equivalent method for ensuring that the 
scrubber absorbent does not deplete, thereby avoiding excessive carbon-
dioxide build-up. Providing a means to manually override these 
functions (i.e., the ``bail-out'' mode) ensures that a diver can 
maintain an adequate supply of air or high-oxygen breathing-gas mixture 
to return to the surface should problems develop with the closed-
circuit or semi-closed-circuit SCUBA. The ``bail-out'' capability, 
therefore, will provide an effective means for divers using closed-
circuit or semi-closed-circuit SCUBA to ascend to the surface in a 
manner that duplicates the safety advantages of open-circuit SCUBA, and 
to do so with an adequate margin of safety (i.e., well within the 
specified ascent rates).

Conditions C to E

    While high partial pressures of oxygen can be poisonous or toxic 
when breathed by divers, current information indicates that oxygen 
toxicity is not a hazard if high-oxygen breathing-gas mixtures are used 
within the limits specified under Conditions C and D above (i.e., at or 
less than a diving depth of 130 fsw equivalent, with a maximum oxygen 
partial pressure delivered to the diver of 1.40 ATA). (See, also, 
References B and C.) Conditions C and D, therefore, limit the maximum 
fraction of breathable oxygen to 40 percent (40%) by volume when using 
open-circuit SCUBA, regardless of the diving depth or oxygen partial 
pressure, and restricts the use of high-oxygen breathing-gas mixtures 
to diving depths of 130 fsw or a maximum oxygen partial pressure 
delivered to the diver of 1.40 ATA, whichever is most restrictive.
    When employees are breathing oxygen partial pressures between 0.6 
and 1.4 ATA in the high-oxygen breathing-gas mixture, Condition E 
specifies that the employer shall comply with the 24-hour oxygen-
exposure limits of the 1991 NOAA Diving Manual or other oxygen-exposure 
limits that are equivalent to the 1991 NOAA Diving Manual oxygen-
exposure limits in terms of protecting divers from oxygen toxicity when 
they are exposed to partial pressures of oxygen between 0.6 and 1.4 ATA 
in the high-oxygen breathing-gas mixture. For the purposes of this 
variance application, the Diving Science and Technology (DSAT) Oxygen 
Exposure Table provides such protection. When the employer chooses to 
use oxygen-exposure limits other than the NOAA or DSAT limits, the 
employer must be able to demonstrate that these oxygen-exposure limits 
are equivalent to, or better than, the 1991 NOAA Diving Manual with 
regard to protecting divers from oxygen toxicity when they are exposed 
to partial pressures of oxygen between 0.6 and 1.4 ATA in the high-
oxygen breathing-gas mixture. The provisions of Condition (E), 
therefore, will ensure that the probability of oxygen-induced central 
nervous system or pulmonary toxicity is not materially greater than 
would occur when using open-circuit, compressed-air SCUBA under the no-
decompression limits.
    A maximum oxygen partial pressure delivered to the diver of 1.40 
ATA delivered to the diver is specified under Condition D because this 
limit is well within the normal oxygen partial-pressure exposure limits 
adopted by NOAA. Under the NOAA limits, the maximum total exposure 
duration to oxygen at a partial pressure (delivered to the diver) of 
1.40 ATA must not exceed 180 minutes during any 24-hour period. (See 
Reference B.) Condition E also refers to the oxygen-exposure limits in 
the DSAT Oxygen Exposure Table. The DSAT Oxygen Exposure Table is more 
conservative (i.e., more protective of divers) than the 24-hour oxygen 
limits promulgated by NOAA; for example, at an oxygen partial pressure 
delivered to the diver of 1.40 ATA, the DSAT Oxygen Exposure Table 
allows a total exposure of 150 minutes during any 24-hour period, 
versus 180 minutes permitted under the NOAA limits. (See Reference D.)
    Condition E also specifies that the time limits in the DSAT Oxygen 
Exposure Table be defined in terms of the total time of the dive (i.e., 
from the time the diver leaves the surface until the diver returns to 
the surface), which is more protective of divers than if the period is 
limited to the bottom time of the dive (i.e., from the time the diver 
leaves the surface until the diver leaves the bottom). The employees 
covered by this variance application will, therefore, be required to 
limit the time they spend at the maximum and intermediary depths so 
they can remain within these time limits; this procedure will reduce 
their exposure to hyperbaric and hyperoxic conditions, and, 
consequently, provide them with an added measure of protection from DCS 
and oxygen toxicity.
    The U.S. Navy has reported no cases of central nervous system 
toxicity, and only two cases of pulmonary toxicity, among Navy divers 
exposed to oxygen partial pressures of 1.40 ATA. (See Reference E.) The 
two cases of pulmonary toxicity, however, resulted after the divers had 
been exposed to the hyperoxic conditions for a total of 55

[[Page 59000]]

hours over a 3-day period, far in excess of the maximum time limit that 
would be used by recreational divers, or permitted under the DSAT 
Oxygen Exposure Table.
    Only a single case of central nervous system toxicity, and no cases 
of pulmonary toxicity, have been documented among civilian divers 
exposed to an oxygen partial pressure of 1.40 ATA. (See Reference F.) 
The single documented case of central nervous system toxicity involved 
a civilian technical sport diver who took an overdose of 
pseudoephedrine hydrochloride, a decongestant, prior to exposure to an 
oxygen partial pressure of 1.40 ATA; the resulting central nervous 
system seizures may well have been caused by the drug overdose, not 
oxygen toxicity alone.
    The U.S. Navy is considering a maximum oxygen partial pressure 
limit of 1.30 ATA, apparently in response to the two pulmonary-toxicity 
cases described in the preceding paragraph. The 1.30-ATA limit is for 
use on dives in which the diver remains at the maximum depth for 
extended periods of time; these dives typically require decompression. 
Application of this limit to Dixie's employees who use high-oxygen 
breathing-gas mixtures is inappropriate because Dixie's employees will 
be limited to no-decompression diving. To ensure that the applicant's 
employees obtain the added protection that results from short-duration 
dives, Condition J of this variance application permits only no-
decompression dives.

Condition F

    The mathematical probability of DCS is elevated with increases in 
diving depth and duration, and if the diver uses breathing-gas mixtures 
consisting of oxygen at reduced partial pressures and high partial 
pressures of a diluent gas (especially helium). Consequently, Condition 
D limits diving to 130 fsw or to a maximum oxygen partial pressure 
delivered to the diver of 1.40 ATA (whichever condition is most 
restrictive), while Condition F restricts the inert gas used to obtain 
the breathing-gas mixture.

Condition G

    This condition was adopted to ensure that the oxygen used in the 
high-oxygen breathing-gas mixture is safe and effective, and 
appropriate for use under no-decompression diving conditions. To remain 
safe and effective, the no-decompression limits used in the NOAA no-
decompression diving tables (see Condition J below) require that 
breathing gases be properly mixed to an accuracy of no less than one 
percent (1%) by volume. Consequently, the high-oxygen breathing-gas 
mixtures must be compounded using the techniques specified in Condition 
G.1. In addition, the fraction of oxygen in the high-oxygen breathing-
gas mixtures used with open-circuit SCUBA, and the fraction of oxygen 
in the breathing-gas loop of closed-circuit and semi-closed-circuit 
SCUBAs, shall be analyzed to an accuracy of one percent (1%) by volume. 
Analysis of the oxygen fraction shall be accomplished using, at a 
minimum, one of the oxygen-analysis methods specified by this 
condition. Also, the manufacturer's instructions shall be used to 
maintain the reliability of the oxygen-analysis method. If the 
breathing-gas mixtures are compounded by a commercial supplier, the 
employer must obtain from the commercial supplier a certification 
document attesting to the fraction of oxygen, the method used to 
analyze the oxygen fraction, and the procedures followed to maintain 
the reliability of the analytic method.
    Pure oxygen that is supplied commercially to the employer must be 
Grade A (aviator's oxygen) or Grade B (industrial/medical oxygen). The 
employer must obtain from the commercial supplier a certification 
document attesting that the oxygen is at least 99.5% pure as specified 
by paragraph 15.3.3. of the 1991 NOAA Diving Manual. The employer must 
also receive from the commercial supplier certification that, at a 
minimum, one of the oxygen-analysis methods specified in Condition G.1 
was used to analyze the oxygen fraction, and that the manufacturer's 
instructions were followed to maintain the reliability of the analytic 
method. Again, these requirements will ensure that only oxygen 
sufficient to maintain a diver's health and safety will be used by the 
applicant's employees.

Conditions H and I

    These conditions require that oil-less compressors or compressed 
air filtered to produce oxygen-compatible air be used to obtain the 
high-oxygen breathing-gas mixtures, and that SCUBA equipment exposed to 
high-pressure (i.e., exceeding 300 psi) high-oxygen breathing-gas 
mixtures and/or pure oxygen be rated for oxygen service. These 
conditions will reduce the chance of fires and explosions by preventing 
petroleum by-products from serving as an ignition source during mixing 
procedures involving elevated levels of oxygen.

Conditions J

    The variance application requires that the applicant's employees 
remain within the no-decompression limits specified by decompression 
tables for single and repetitive air diving developed and published in 
the 1991 NOAA Diving Manual; the employer may use other decompression 
tables, formulas, and/or principles for this purpose provided the 
employer demonstrates that these tables, formulas, and/or principles 
are equivalent to, or better than, the NOAA decompression tables and 
formulas. This condition was adopted to achieve an equivalent or lower 
mathematical probability of DCS when compared to recreational diving 
instructors covered by paragraph 29 CFR 1910.401(a)(2)(i) of the OSHA's 
Commercial Diving Operations standard. Consequently, this condition 
eliminates the need for a decompression chamber at the dive site, 
provided that the other conditions specified in the variance 
application are followed.

Condition K

    When OSHA adopted the Commercial Diving Operations standard in 
1977, divers typically relied on printed diving tables to plan their 
dives, and no-decompression limits were developed under the assumption 
that a diver would remain at one planned depth for the duration of the 
dive (i.e., ``square-wave'' diving). No-decompression limits for a 
subsequent dive made within 12 hours of a previous dive were determined 
using special extensions of the decompression tables; these extensions 
required that tedious and time-consuming calculations be made by hand. 
Consequently, any errors resulting from these calculations placed the 
diver at an increased probability of developing DCS.
    Underwater dive-decompression computers, which were not widely 
available in 1977, are now commonly used by recreational divers to 
perform no-decompression calculations automatically; these calculations 
are based on diver's previous multi-level diving profiles, inclusive of 
diving depth and duration. The time remaining for subsequent no-
decompression dives (i.e., the adjusted no-decompression limit) is 
accessible to the diver throughout the dive via the liquid crystal 
display (LCD) screen on a module that, typically, has been incorporated 
into an instrument console mounted on the end of the submersible 
pressure-gauge hose, or worn separately on the diver's wrist. This 
feature eliminates the need to calculate no-decompression limits 
manually, and to

[[Page 59001]]

remember the depths and durations allowed for subsequent repetitive no-
decompression dives. Dive-decompression computers, therefore, provide 
divers with continuous and instant access to adjusted no-decompression 
diving limits. This information can be used to plan subsequent 
repetitive dives by determining the no-decompression time remaining. 
Dive-decompression computers may also calculate and display, either 
digitally or graphically, the diver's: vertical ascent rate, which 
assists them in maintaining safe and controlled ascents to the surface; 
and breathing-gas consumption rates and oxygen loadings, either for 
single dives or over 24-hour periods, which aids divers in planning 
their subsequent diving activities.
    After a diver reaches the surface, a dive-decompression computer 
automatically transfers the data collected during the dive into an 
electronic log that can be accessed and viewed on the LCD screen, and 
then entered in the diver's log book. Many dive-decompression computers 
also store the profile data of a dive (e.g., depths, times) for 
subsequent downloading to personal computers; once downloaded into a 
personnel computer, the data can be displayed in a tabular or graphic 
format, and manipulated for statistical purposes. This feature also 
enables analysis of precise dive-profile data in the event of a diving 
accident.
    In summary, dive-decompression computers assist divers in 
decreasing their exposure to excessive ascent rates, oxygen toxicity, 
and DCS that could result from errors in calculating repetitive no-
decompression diving schedules manually. Also, dive-profile information 
can be stored for subsequent viewing and downloading, thereby 
preventing errors that may result if the divers fail to record the 
information, or do so erroneously. Condition K, therefore, permits the 
applicant's employees to use dive-decompression computers to avoid the 
calculation and recording errors that could be made in determining 
adjusted no-decompression diving limits.
    To ensure that the decompression schedules calculated by the dive-
decompression computers are valid (i.e., conform to NOAA no-
decompression air tables or formulas, or other equivalent tables, 
formulas, and/or principles as the basis of the decompression 
calculations. In addition, Condition K.2 specifies that these 
calculations must reliably represent the tables, formulas, and/or 
principles (i.e., the results determined by the dive-decompression 
computer for decompression stops, ascent and descent rates, and 
surface-interval determinations must be the same results that would be 
obtained using the model, formula and/or principles on which the dive-
decompression computer calculations are based).
    Conditions K.3 and K.4 have been included to provide backup 
procedures should the results calculated by the dive-decompression 
computer be lost or become unavailable for some reason. The information 
obtained under Condition K.3 can serve to reconstruct the diving 
schedule used previously by a diver, as well as assess the reliability 
of dive-decompression computers for dives that involve a diving-related 
medical emergency. Condition K.4 will provide the diver with 
immediately-accessible decompression information when such information 
is not available from the dive-decompression computer.
    The provisions of Condition K will ensure that: the decompression 
procedures calculated by dive-decompression computers are accurate and 
appropriate to the diving conditions specified in the variance 
application; the reliability of the dive-decompression computer has 
been determined; and decompression information is readily accessible if 
the dive-decompression computer fails, is lost, or is damaged. These 
provisions, together with the detailed operating instructions provided 
by the manufacturers of dive-decompression computers, will ensure that 
dive-decompression computers are used appropriately. Consequently, the 
dive-decompression computers will improve diver safety by reducing 
errors made in determining decompression schedules.

Conditions L to N

    As noted in the earlier discussion of Conditions C to E, the 
mathematical probability of DCS resulting from the use of open-circuit, 
closed-circuit, or semi-closed-circuit SCUBA supplied with high-oxygen 
breathing-gas mixtures is expected to be lower than the DCS incidence 
associated with the use of open-circuit, compressed-air SCUBA. 
Nevertheless, the divers covered by this variance application will 
receive added protection from DCS by implementing the measures 
described under Conditions L to N. The procedures specified in 
Conditions L to N will ensure that decompression chambers and other 
medical facilities have been identified and are available should a 
diving-related medical emergency occur at the dive site. Requiring the 
employer, under these conditions, to plan and prepare for diving-
related medical emergencies will provide the divers covered by this 
variance application with an additional margin of safety compared to 
divers who experience DCS and other diving-related medical emergencies 
while using open-circuit, compressed-air SCUBA.

Conditions O and P

    Condition O requires the applicant to hire and use only divers who, 
when they dive under the conditions specified in the variance 
application, have been certified by a diving training agency that is 
recognized by the recreational diving industry as possessing the 
qualifications necessary to effect the conditions specified in the 
variance application; the divers must also be capable of conducting 
dives consistent with these conditions. In addition, the employees must 
perform the functions of recreational diving instructors or diving 
guides when they dive under the conditions specified in the variance 
application. Condition O provides general uniformity to the diver 
qualification and training process, as well as quality control over the 
certifying agencies.
    The applicant states that the requirements of Conditions O and P 
will ensure that the employees covered by this variance application are 
trained to perform diving procedures, use diving techniques, and 
operate diving equipment in a manner that is acknowledged by the 
recreational diving industry as being safe and effective, and that are 
consistent with the conditions specified in the variance application.

IV. References

    Copies of the following references can be obtained from Ms. Juanita 
Jones at OSHA's Office of Variance Determination (see FOR FURTHER 
INFORMATION CONTACT above).
    A. Richardson, D. (1995). An Assessment of Risk for Recreational 
Dive Instructors at Work. Undersea Journal, 2nd quarter, p. 14.
    B. National Oceanic and Atmospheric Administration (1991). NOAA 
Diving Manual: Diving for Science and Technology, Chapter 15. U.S. 
Government Printing Office, Washington, D.C.
    C. Hamilton, R.W. (1996). Justification for Allowing Recreational 
Divers To Use Oxygen-Enriched Air. Prepared for International PADI 
(Professional Association of Diving Instructors or ``PADI''), Inc., 
Santa Ana, California.
    D. Diving Science and Technology (1995). Analysis of Proposed 
Oxygen Exposure Limits for DSAT Oxygen Exposure Table Against Existing

[[Page 59002]]

Database of Manned Oxygen Test Dives. Enriched Air Resource Guide. 
PADI, Santa Ana, California.
    E. Hornsby, A. (1996). Response to OSHA Draft Variance Application. 
Cited on p. 2 of a facsimile dated October 11, 1996 to Mr. Bill Ford of 
Patton Boggs, L.L.P., from PADI, Santa Ana, California.
    F. See Reference E, p. 3.

V. Additional Information

    Copies of this variance application are available from OSHA's 
Office of Variance Determination or the Regional and Area Offices 
listed above under FOR FURTHER INFORMATION CONTACT, or through the 
Labor News Bulletin Board at (202) 219-4748 or OSHA's web page on the 
Internet at http://www.OSHA.gov.
    All interested parties, including the employers and employees, who 
believe they may be affected by the approval or denial of the variance 
application are invited to submit written data, views, and arguments 
relating to this application no later than December 30, 1997.
    Under 29 CFR 1905.15, interested parties, including the employers 
and employees, who believe they may be affected by the grant or denial 
of this variance may request a hearing on the variance application no 
later than December 30, 1997. The original and four copies of written 
comments and requests for a hearing must be addressed to OSHA's Office 
of Variance Determination; for further information on submitting 
comments and requests for a hearing, see ADDRESSES above.

VI. Issues

    In submitting comments on the variance application, OSHA invites 
the public to submit information (e.g., reports, case histories, 
statistical analyses, data) and specific comments and rationale on the 
following issues:
    A. Differences between recreational diving instructors and diving 
guides in the underwater tasks and type of diving they perform, and the 
relationship of such differences to an increased probability of 
experiencing diving-related medical problems;
    B. In general, the health and safety effectiveness of closed-
circuit and semi-closed-circuit SCUBA if used under the conditions 
specified in the variance application;
    C. In general, the health and safety protection afforded by high-
oxygen breathing-gas mixtures, if used under the conditions specified 
in the variance application;
    D. The health and safety protection provided to divers using the 
carbon-dioxide scrubber, sensor, and other control measures described 
in Conditions A.1 and A.2 of the variance application;
    E. The adequacy of the ``bail-out'' provisions specified in 
Condition A.4 of the variance application;
    F. The engineering and maintenance reliability of closed-circuit 
and semi-closed-circuit SCUBA, including the features specified in 
Conditions A and B of the variance application;
    G. The adequacy of the methods used to obtain and analyze high-
oxygen breathing-gas mixtures, especially the semi-permeable-membrane 
method, described in Condition G of the variance application;
    H. The extent to which the conditions specified in the variance 
application will protect employees who are engaged in repetitive 
diving, including the use of (1) available decompression tables, 
formulas, and principles to prevent DCS, and (2) oxygen-exposure limits 
from the 1991 NOAA Diving Manual, DSAT Table, or other equivalent 
limits to protect divers from oxygen toxicity; and
    I. The provision specified in Condition O of the variance 
application regarding the use of ``a training agency recognized by the 
recreational-diving industry'' to certify the applicant's employees.

VII. Authority and Signature

    This document was prepared under the direction of Gregory R. 
Watchman, Acting Assistant Secretary of Labor, U.S. Department of 
Labor, 200 Constitution Avenue, N.W., Washington, D.C. 20210, pursuant 
to Section 6(d) of the Occupational Safety and Health Act of 1970 (29 
U.S.C. 655); 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), or 6-96 (62 FR 111), 
as applicable; and 29 CFR Part 1905.

    Signed at Washington, D.C., this 24th day of October 1997.
Gregory R. Watchman,
Acting Assistant Secretary of Labor.
[FR Doc. 97-28930 Filed 10-30-97; 8:45 am]
BILLING CODE 4510-26-M