Notice of Application for Permanent Variance From Dixie Divers

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