[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]
-----------------------------------------------------------------------
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.
-----------------------------------------------------------------------
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