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QUESTION:
"Should NAUI offer training through a specialty program
in Nitrox Diving? Why/why not?"
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Compiled and
edited by Jeffrey Bozanic
The propriety
of sport divers utilizing advanced or specialized equipment, diving
into environments more hazardous than "typical" open water
environments, or practicing diving techniques not considered to be
within the realm of "recreational" diving has traditionally
generated controversy. Past and current examples of debatable practices
include penetration wreck diving, alternate second stage use, cave
diving, planned stage decompression diving, buoyancy compensator use,
oxygen decompression, ice diving, rebreather based SCUBA systems,
and solo diving. The use of gas mixtures other than air also fall
into this category. In this month's column, we examine the question
of nitrox training and use.
While nitrox
mixtures include air with both lower and higher percentages of the
oxygen component than that found in air, all of the respondents considered
only the type of mix in which the oxygen percentage was increased.
The proponents who favored NAUI offering training in nitrox use, as
well as many of those opposed to such specialty training, agreed that
there were several benefits to an enriched air nitrox (EANx) mixture,
including: longer bottom times, a greater safety margin with regards
to decompression sickness, shorter surface intervals, and reduced
decompression obligations.
Other non-physiological
benefits detailed were the opportunity for market expansion and development
opportunities, and the prospect for additional continuing education
programs. The most persuasive argument raised was that since the numbers
of sport divers using nitrox is rapidly escalating, that NAUI would
be negligent in not providing training for those desiring it.
The majority
of the members submitting opinions opposed a nitrox diving specialty
program (60/40 against). The arguments they advanced were primarily
technical, including the lack of a readily available and safe nitrox
mix gas supply, the need for oil free compressors, the need for equipment
designed and cleaned for oxygen use, and the increased complexity
and hazards involved in recompression treatment of divers with DCS
or embolism problems after diving with nitrox. Some of these problems
could lead directly to cases of oxygen toxicity or decompression sickness.
The majority
also felt that nitrox use was too complex and expensive for the average
sport diver. Looking at the number of accidents which occur by divers
improperly using air, a mix requiring a relatively simple set of procedures;
the consensus belief was that more control over nitrox use is required.
A common fear was that standard safety precautions used in the commercial
or scientific communities would be ignored because of the expense,
for example analysis of the final mix because of the high cost of
the oxygen analyzing equipment.
Polarization
in beliefs regarding the physiological safety of nitrox use also existed.
While the U.S. Navy, commercial diving companies, and scientific divers
have all been using nitrox for many years, there is a paucity of published
data on the reliability of that use. Some of the respondents therefore
feel that nitrox use should be considered experimental, until controlled
research is conducted. Activists counter this by pointing to the large
number of dives which have been successfully executed in a wide variety
of environments and by an assortment of different groups.
Ultimately,
the question comes down to a question of risk. Certainly, nitrox use
entails more risk than does the use of air for diving in today's recreational
community. The question of risk as posed by most of the respondents,
however, looked to the actual use and/or abuse of nitrox as a breathing
medium. Evolution in equipment and techniques, especially in the area
of gas mixing, could do much to ameliorate this danger.
I would, however,
pose the question of risk differently...if training in nitrox use
is not available, would the number of divers injuring themselves be
greater or less than those who would do so because of the increased
use of nitrox if training was available? Regardless of whether or
not NAUI sanctions training in nitrox diving, abuses will occur. We
cannot prevent all misapplications, and must expect accidents and
fatalities to occur. If we fail to provide accessible training, then
mishaps will occur as divers blindly misuse nitrox as a result of
inadequate knowledge. If we do offer training, accidents will occur
because of wider use and carelessness. As dive industry leaders, we
must decide which is the proper course to follow to insure that the
industry remains as safe as possible.
======================================================
QUESTION: "SHOULD
NAUI OFFER TRAINING THROUGH A SPECIALTY PROGRAM IN NITROX DIVING?
WHY/WHY NOT?
A. This is
a tough question to answer. On one hand, use of nitrox or other mixed
gasses historically do not fit into the definition of "sport
diving." However, divers are using dive computers in such a manner
that a few years ago also was not defined as sport diving. This is
acceptable procedure today.
On the other hand, if the market is using nitrox, and the need for
education is growing, then NAUI should consider instituting a specialty
course in nitrox diving. After all, our motto is "Safety Through
Education." Since nitrox use is increasing, we should implement
a Nitrox Diving specialty program.
--Struther
MacFarlane, NAUI 6676; Toronto, Ontario, Canada
(As a private professional educator, has taught all levels from introductory
to serving as ITC Director. Recipient of the NAUI Canada Silver Pin
and Special Recognition Awards.)
A. In a commercial
or scientific diving setting controlled by a diving control board
with an on-site diving supervisor, I have no problem with mixed-gas
diving. Virtually all recreational diving has little to no supervision,
and 99% of all divemasters and instructors know nothing of supervising
a mixed-gas dive. After almost 28 years as a teaching organization,
I sometimes wonder if we have even yet figured out how to keep divers
safe on air. Now here we go toying with the idea of giving these same
divers a breathing mix that depending upon its composition cannot
be taken below 130 feet or 100 feet for fear of oxygen toxicity.
--Jim
Corry, NAUI 7184L; Washington, D.C. (Has taught all levels to ITCs
both privately and at UCLA. Currently serves as Chairman of the Diving
and Water Rescue Committee of the National Association for Search
and Rescue. Has authored many articles about diving safety. 1989 Recipient
of the Greenstone Award.)
A. Yes, because
it would help the liability exposure facing the training organizations.
Our diver population is aging, and using an Enhanced Air Nitrox (EANx)
mixture for these divers can enhance their safety margin physiologically.
Training is vital with this type of diving. It is important that the
divers understand Equivalent Air Depth (EAD) and oxygen toxicity concepts,
to prevent abuses of these gas mixtures. But we must remember that
WE WILL NOT PREVENT ALL ABUSES. There have been and continue to be
numbers of divers who abuse compressed air use. We must expect the
same with nitrox use.
EANx will also open a new market for dive stores, both in equipment
sales and especially with continuing education. Very little new equipment
is needed by the divers--only nitrox dedicated cylinders. The major
expense can be borne by the dive stores (mixing systems, oxygen analyzers),
which can spread the expense across a very large diving base population.
--Billy
Deans, PADI OWSI 9283; Key West, Florida Keys, FL (Teaching since
1978, owns Key West Diver, Inc. dive store. Has extensive experience
with nitrox diving and other mixed gas media.)
A. I do not
feel that nitrox use is appropriate for sport divers. Our understanding
of the physiological effects of this kind of exposure is deficient
with only minimal documentation being available (ie. In the public
domain at least). Further, additional knowledge and care is required
for safe gas mixing, testing, and calculation of decompression status,
especially if a "dial-a-mix" system is employed. Although
these skills can surely be taught, I believe that the fundamental
argument is clear. Any mixed-gas diving (such as nitrox) is more complex
than air diving and the added degree of environmental manipulation
is outside the acceptable parameters for a recreational activity.
--Neal
Pollock, NAUI 7068; Vancouver, British Columbia, Canada (Diving Officer
for the University of British Columbia, and current President of the
Canadian Academy of Underwater Sciences. Past candidate for the NAUI
Canada Board of Directors.)
A. Unless there
is firm evidence that makes nitrox incompatible with safe diving practices
we should learn as much as we can about it and help educate the diving
public as to the best way to use nitrox. A specialty course might
be the easiest way to impart that information.
Bob
Widmann, NAUI 2055; Aptos, CA (Past Mid Pacific Branch Manager. Has
taught all levels of diving, including having served as ITC Director.
Recipient of NAUI Outstanding Service Award.)
A. NAUI should
not implement a specialty course in Nitrox Diving at this time. We
still do not have enough experimental data with nitrox tables to sanction
their use with humans. For example, there is no research which has
been done using nitrox in repetitive diving situations. More animal
research should be done before nitrox use is routinely used by divers.
Once the animal research is completed, then 10,000-15,000 documented
dives with people should be conducted on an "experimental"
basis before NAUI considers endorsing such a program.
There also are potential problems with nitrox use once it is approved.
One such are the problems and risks involved with recompression chamber
treatments, especially if the chamber personnel do not realize that
the diver(s) was using nitrox during the dive. This complicates the
oxygen toxicity problems, as an increased oxygen toxicity problem
exists even after the dive is completed.
Another major problem relates to the mixing procedures used to get
the nitrox breathing media. I am amazed that more people in Florida
and other locales where nitrox is commonly used have not had more
mixing-related accidents. At least two gas analyzers should be used
to measure final oxygen content, and this is not routinely done by
those groups.
This issue should not be ignored. More research should be done, and
educational articles discussing both the benefits and increased risks
of nitrox use should be written. It would not be inappropriate for
NAUI to publish such articles in Sources to inform the membership
of progress which is made.
--Art
Bachrach, PhD; Taos, New Mexico (Past Director of Environmental Stress
Program Center and Chair of Science in Psychophysiology, Naval Medical
Research Institute; and Adjunct Professor of Medical Psychology, Uniformed
Services University of the Health Sciences. Current member, NAUI Board
of Advisors. Has authored many papers and textbooks on stress and
diving.)
A. OK, why
not?
--Jerry
Schnabel, NAUI 2464; Bonaire, Netherlands Antilles (Photo pro for
Divi Resorts in Bonaire. Has taught primarily Underwater Photography
specialties, but also has entry level thru ITC teaching experience
at many resorts in the Caribbean.)
A. Nitrox diving
must be done correctly. Special gas mixes can be used in the recreational
community if it is done correctly. If a person is technically qualified
and motivated enough to acquire the proper equipment to use special
gas mixtures properly, then using an enriched air nitrox (EANx) could
lead to a lower of risk decompression problems than than using air.
But to get to that point, EANx must be employed precisely.
The big problem with divers who receive inadequate training or no
training and make procedural mistakes while using nitrox. The primary
risks include: (1) oxygen toxicity from using an improper mix (final
gas mix was not analyzed), (2) inadequate decompression from using
an improper mix, and (3) the technical risk of handling 100% oxygen,
especially in the typical dive store environment.
However, people are using nitrox. The divers using it are not breaking
any laws, so they will continue to use nitrox and convince others
to do so also. The dive training agencies should not ignore this problem--it
is not going to go away. The certification agencies cannot avoid addressing
this problem, it is inevitable that they develop training standards
and procedures to address the nitrox diving issue. Training in nitrox
diving should be provided.
--R.
W. "Bill" Hamilton, Tarrytown, NY (In 1964 started work
in laboratory of Union Carbide Corp. for Ocean Systems doing commercial
diving research related to gasses and physiology. Since 1977 has been
President of Hamilton Research Ltd. working as a gas physiology consultant
for a variety of navies and commercial firms.)
A. Diving on
nitrox with SCUBA, for the average diver, is probably not much different
than diving with air. Very little change other than using different
tables, specially cleaned gear, special testing equipment, and having
to find a special supplier exist. But for these reasons, and others,
nitrox diving is not for the average recreational diver and definitely
requires special training.
My primary objection to the use of recreational nitrox diving is not
with the diver--it is with the source of the gas. Nitrox, by definition,
is a mixture of nitrogen and oxygen, to the exclusion of all other
gasses. For breathing by divers both gasses should be medical grade
and certified. Most operations I have heard about are really using
"sweetened air" rather than true nitrox. Air tends to be
somewhat dirty by graded standards, but divers are used to it. In
our operations here at the Catalina Hyperbaric Chamber we use a 47/53
nitrox mix--purchased, not mixed locally. I have done gas mixing with
both nitrox and heliox (helium and oxygen) breathing mixtures. For
the well trained technician, mixing is not a problem; however for
the "high school kid in the shop" filling tanks and maintaining
the proper mixture could be. (But then, every good nitrox diver should
carry around his own oxygen analyzer anyway.)
NOAA Nitrox I is the most popular nitrox table being talked about
today. If NAUI cannot accept any of the newer, well tested, and proven
air tables available how can they plan to adopt experimental nitrox
tables? Yes, the NOAA tables have been in print for many years, but
how much formal testing has been done on them? If the nitrox mix varies
by as much as 1% from standard (32% oxygen), the NOAA tables are no
longer valid. What tables do you use then?
And do not forget oxygen cleaning. Many proponents are suggesting
that special cleaning is not required for mixes with less than 40%
oxygen. A more acceptable standard is probably 25% oxygen. Any time
a breathing mix exceeds 25% oxygen the equipment requires special
cleaning, and perhaps having some of the parts exchanged for more
oxygen tolerant materials. Once air has been put to the specially
cleaned gear it should be considered contaminated, and recleaned prior
to using "sweet" mixes again.
NAUI should stay out of the business of nitrox. Leave it to those
few specialists who have the experience and knowledge to pass on their
training to those few who need the special skills.
--Ronald
J. Ryan, NAUI 7205; Two Harbors, Catalina Island, CA (Supervisor,
Catalina Hyperbaric Chamber. Past employee in the commercial diving
industry, where his duties included mixing special gasses for diving.)
A. Nitrox was
in use before most divers in this country were born. For decades,
the U.S. Navy and commercial diving companies have successfully used
nitrox mixtures for increasing diving efficiency. More than a decade
ago, NOAA recognized the significant advantages obtained by the use
of nitrox, and published tables and procedures for its use in the
1975 edition of the NOAA Diving Manual.
Only within the last 5 years has the scientific and advanced level
sport diving community began to take advantage of the numerous benefits
of nitrox (increased bottom times, reduced residual nitrogen times,
reduced nitrogen narcosis, shorter surface intervals, and safety).
Why safety? Simple. The existing Nitrox Decompression Tables (NOAA
Nitrox I) are simply more conservative than the U.S. Navy Air Decompression
Tables upon which they are based. Scientists from over a dozen universities
have performed thousands of nitrox dives, as have progressive sport
diving groups.
The demand for good training in nitrox diving has stimulated the formation
of the International Association of Nitrox Divers, and American Nitrox
Diving, Inc. Detailed information covering the advantages and limitations
of nitrox, safe and efficient methods for its preparation, and equipment
and techniques necessary for its use are all nitrox diving training
programs. While the use of nitrox is not for all divers, its use has
advantages for many. There is no reason that this information could
not be provided for those individuals by the national certification
agencies. [Ed. note: NASDS has at this time sanctioned the use of
nitrox in a nitrox diving specialty course.]
--Dick
Rutkowski, NAUI 4563; Key Largo, Florida Keys, FL (President of Hyperbarics
International, which conducts training programs for divers and instructors
in nitrox diving. Past diving officer for NOAA, where he helped pioneer
the use of nitrox diving in research tasks.)
A. I believe
that the concepts (equivalent air depth and the dive tables) that
enriched air nitrox use is based on are sound. However, there has
been very little actual testing/use to prove the safety of its use.
It is my opinion that the use by the sport diving community, if approved,
will provide the data base to validate these theories. This is not
bad or unacceptable--the U.S. Navy tables had very little testing
when they were released, and were validated through use.
If nitrox diving is approved by NAUI, however, then I believe that
the existing tables should be slightly modified to provide a greater
margin of safety.
My biggest concern with nitrox diving is the production of the breathing
gas mixture itself. I have strong concerns about the ability of the
average dive store employee to provide a safe mixture. The proper
gas mix is critical to the safety of the diver--too high a percentage
of oxygen, and the diver could develop oxygen toxicity. Too little
oxygen, and the divers do not have the margin they are planning on
with nitrogen uptake, and may get bent. If automated equipment was
available that had very high reliability for providing the proper
mix, I would be less concerned with approving nitrox use.
--Andy
Pilmanis, PhD; San Antonio, TX (Currently involved in hyperbaric research
for NASA in support of space program activities. Past Director of
the Hyperbaric Chamber at the Catalina Marine Science Center at the
University of Southern California. Has published extensively and lectured
on diving safety and hyperbaric medicine.)
A. Having been
asked this question quite frequently, I have several conversations
regarding this with individuals from various certifying agencies,
insurance companies, dive shops, and sport divers in the truest sense.
To speak of nitrox, most people tend to dwell on the bottom time advantage.
This is quite impressive in many cases, but there are other issues.
1. From a practical sense, the cost is prohibitive for most people,
since one must purchase oxygen analyzers, cylinders to dedicate to
nitrox use, etc., which may run as high as an extra $1000.
2. A major concern would be that of control. Who is to monitor the
fill stations' mixing procedures and quality of gas? Who sets the
standards? There appears to be enough difficulty in dealing with air.
3. We know from discussions with sport divers and with the growing
interest in dive computers, that divers are conducting multi-level
diving. With nitrox, a great deal of this flexibility is lost. Once
a depth is determined for that given mix, one cannot descend any deeper.
Therefore, a depth must be strictly adhered to with no option for
going deeper. Once this is realized, many of the divers inquiring
about nitrox realize that it is not quite what they thought.
4. From discussions with individuals in the insurance field, it does
not appear that they are willing to support nitrox use. A great deal
has been written regarding nitrox, with the majority of the agencies
have publicly stated that they are against nitrox use, so the insurance
companies do not seem supportive at this time. The current question
is, if a diver gets injured now, will he/she be covered since nitrox
diving is not currently considered "recreational" diving?
5. From a treatment standpoint, it is quite common for the injured
sport diver to be inaccurate relating dive profiles. Without being
derogatory about the divers' intelligence or competence, it is a common
observation that the divers admitted for treatment have not paid close
attention to their profiles. If this is the case with air, perhaps
we may want to reevaluate diver training again before embarking on
an ambitious project such as nitrox.
I am not presently supportive of nitrox use in sport diving. It is
difficult for me to say this; being a diving physiologist I certainly
appreciate the safety/health factors it provides. I would support
nitrox use in the sport diving community if three things could be
accomplished: (1) All divers were trained in its use since it would
be readily available, (2) all stores were educated in the proper mixing
procedures and followed the same standards, and (3) the insurance
companies support its use so that any litigation would be covered
and all accident-related problems were covered.
The question must be asked, "Do the benefits outweigh the risks?"
Only the agencies can answer this.
--Dudley
J. Crosson, PhD, NAUI 8838; Port St. Lucie, FL (Owner of Delta P,
providing services to firms needing specialized supervision and training
in advanced diving technologies, including special gas mixtures. Past
Diving Safety Officer/Diving Physiologist for the Florida Institute
of Technology Underwater Technology Program, and Diving Officer at
the Harbor Branch Oceanographic Institution.)
A. NAUI has
always stood for "Safety Through Education." Once a new
method or technique, such as nitrox, has been refined and is ready
for implementation by the sport diving community NAUI should offer
the appropriate training and certification. It is questionable whether
sport diving has a legitimate need for this technique considering
the increased complexity of diving operations versus the benefits
from increased bottom time. I do not feel that presently all facets
of this technique have been investigated to the level required for
widespread use by the general diving community.
Our diving staff at the National Undersea Research Center implemented
an enriched air (nitrox) program in 1986 for support of ocean science
investigations. To date, we have made over 600 dives using enriched
air between 60 and 130 fsw with no incidents. We feel this safety
record is due to the care and special attention paid to equipment
and technique by our professional staff.
Diving an EANx mixture is, for the diver, no different than air. The
equipment worn and the procedures used are generally the same. However,
EANx diving requires the diver to be well versed in such topics as:
central nervous system oxygen toxicity, equivalent air depth, partial
pressures of oxygen, and nitrox repetitive diving tables. The diver
should also be instructed in gas mixing techniques and gas analysis
even though others (such as a dive shop or resort) may be responsible
for this function. All these topics could be properly covered by NAUI
instructors through a nitrox specialty course.
The gray area with enriched air is equipment, which can be split into
two types, diver-worn and gas mixing equipment. Any equipment exposed
to concentrations of oxygen greater than air must be designed for
such service. Because SCUBA equipment is designed for use with air,
the materials and lubricants used may not be safe for EANx mixtures.
In an effort to answer some questions in this area I canvassed all
major manufacturers of SCUBA equipment (via questionnaires) asking
if their cylinders, regulators, and/or BCs were compatible with enriched
air use. I received little response and concluded this was due to
the fact that most major manufacturers have not yet determined whether
or not their product can be safely used with EANx mixtures. Mixing
equipment is a problem because there is not a commercially available
enriched air mixing system. Each enriched air station must be custom
designed and built without the aid of specific guidelines. If this
is not done correctly by knowledgeable persons, serious problems can
arise. Gas mixing using pure oxygen is at best an art and at worst
extremely dangerous.
Enriched air diving is a safe and proven concept. However, we must
wait for new developments in equipment technology before widespread
use by the sport diving community should be considered or endorsed.
Recreational diving is still viewed by the majority to be a high risk
activity. Great strides have been made toward disproving this notion,
and it would be a disservice to the sport to let a few zealous individuals
lead us too far too fast. NAUI must live up to the ideology of safety
first.
--Stephen
J. Mastro, NAUI 6094; Wilmington, NC (Diving Coordinator for NURC/UNCW,
trains scientific divers in advanced diving techniques, designs and
constructs enriched air mixing systems. Published papers on operational
use and mixing of enriched air.)
A. Nitrox is
a gas mixture of oxygen and nitrogen in different proportions than
those found in the air (or compressed air) we breathe. Getting the
proper mixture may be tricky stuff: if your mix has too much nitrogen,
you may not get the expected benefits of reduced narcosis and increased
no-decompression limits. If it does not have enough, the partial pressure
of oxygen might get too high then: beware of oxygen toxicity!
With compressed air, the 80% N2 -- 20% O2 mixture is easy to remember,
and all our dive tables and computers take those percentages for granted.
With nitrox, an almost infinite number of mixture combinations is
possible...the decompression profile will then undoubtedly change
but to what table should you refer to for your special mix? It is
too easy to get a "wrong" mix, I therefore disagree with
the idea of any specialized course in nitrox for sport diving.
--Martin
Poirier, NAUI 10040; Cartierville, Quebec, Canada (Teaches part-time
for Ecole de plongee sous-marine Triton, a NAUI Pro Facility. Teaches
primarily Openwater I classes, and enjoys ice and wreck diving.)
A. Equivalent
Air Depth (EAD) sounds like a reasonable concept, but it has not yet
been proven. Before nitrox diving is accepted as a "safe"
standard, the concept needs experimental validation. A minimum of
50,000 dives should be conducted under supervised conditions with
each gas mixture before that mixture and associated tables are routinely
utilized.
Dives which have been conducted using "home-brews" mixed
in a garage should not be included in this data base. There is no
control on such dives, and no post-dive standardized reporting mechanism.
The content of the gas mix used in these dives is especially suspect,
as at least two calibrated oxygen analyzers should be used to verify
the mixture prior to diving.
You do not get something for nothing. Before toting "doubled
no-decompression bottom times" and "increased safety margins,"
the increased risk of oxygen toxicity should be considered. The mechanisms
behind oxygen toxicity are poorly understood, and also require more
experimental data.
Because of these factors, I do not feel that the time is right for
NAUI to consider implementing a Nitrox Diving specialty course.
--Dr.
Glen Egstrom, NAUI 937L; Los Angeles, CA (Dive Officer for University
of California, Los Angeles. Member NAUI Board of Advisors. Past President
NAUI. Has taught all levels from Entry level to ITCs. Has authored
many textbooks and articles on diving safety, and has lectured extensively.
Recipient NAUI Outstanding Service Awards.)
A. The use
of various nitrox mixtures has been around for years, only recently
having been considered by recreational divers. Historically, it has
been of significance only to commercial commercial and research interests
in terms of the cost/benefit ratio. The benefits are that bottom time
is extended and the decompression obligation is reduced due to lower
nitrogen partial pressures. These groups exercise their technological
capability to precisely mix, analyze (with redundant oxygen analyzers)
and properly supervise the application of nitrox.
If we try to justify use of nitrox by the recreational community based
on its successful use in either the scientific or commercial communities,
we immediately see that problems exist. Nothing remotely close to
the same level of organization, technical discipline, or emergency
support currently exists within the general recreational diving population.
The cavalier attitude demonstrated by many sport divers could lead
to short cuts in the gas mixing process, and the creation of "home
brews." Errors in mixing or applying the mix to dive tables could
result in oxygen toxicity or decompression sickness. If an incident
were to occur, the effectiveness of appropriate chamber treatment
might be compromised due to the cumulative toxic effects of recent
exposure to high partial pressures of oxygen.
Considering these risks, where are the benefits? In order for the
risk/benefit ratio to favor nitrox use, the increase in bottom time
must be significant, since reduced decompression obligation has little
value to a population who supposedly do not conduct decompression
dives. While the potential of increased bottom time does exist, the
DCS risk inherent in the selected set of tables must also be examined.
Conservative tables lower the risk of DCS but generally do not provide
the desired increase in bottom time. In the use of nitrox, as with
decompression diving, the risk/benefit ration may not favor the diver.
From this perspective, it may be better to err with air.
--Dan Orr, NAUI
????; Tallahassee, FL (Assistant Director and Associate Diving Officer
of the Academic Diving Program at Florida State University. Former
NAUI Mid-America Branch Manager. Has authored numerous articles on
diving safety topics, as well as spoken on nitrox use at a variety
of diving symposiums. Recipient of the NAUI Outstanding Service Award.)
A. NOAA Nitrox
I (32/68), when used correctly and according to the instructions,
is more safe for divers than air. Ignore the clearly defined protocols
and, as with anything, the dangers increase with the magnitude of
the individual's stupidity. Training to use Nitrox I correctly is
short but essential. The rules for its safe use are neither complex
nor too long to remember. Nitrox I must not be used at depths greater
than 130 feet, and it must be blended in a precise and accurate way.
Unfortunately, some not so precise methods are in use today and there
is no safety net at the maximum allowable depth to stop those who
do not understand why the gas does not allow deeper diving.
Divers have some options, depending on their needs, in how they choose
to take advantage of Nitrox I. In general, bottom time is nearly doubled
if the diver needs that time. However, when far from a hyperbaric
chamber, the "enriched air" diver may use standard air tables
and benefit from a greatly increased safety margin.
Quality training in all phases of nitrox use is now commercially available.
Those who criticize the use of nitrox by sport divers, including some
leaders within NAUI, should take the training. They might recognize
the dive industry is at exactly the same place with Nitrox I today
that we were with cave diving 15 years ago. Some dedicated leaders
said then we should ban cave diving (a classic example of putting
one's head in the sand). Clearer heads held that experts in the cave
diving associations should lead the way. They did; and when pursued
conservatively, cave diving risks are acceptable. The instructor associations
should follow a similar path for safe introduction to Nitrox I as
it can be the cutting edge of diving technology for the 1990's.
--Bill High, NAUI
175; Seattle, WA (Director, Professional Scuba Inspectors. NOAA Nitrox
II trained mixer and user. Past President of NAUI, and recipient of
NAUI Outstanding Service Award.)
A. No, I do
not think NAUI should offer a specialty course in Nitrox diving. Nitrox
is beyond the scope of sport diving. Being a professional diver as
well as an instructor I have been involved in nitrox diving operations.
The preparation and care for equipment used in nitrox diving is much
more involved than that used with air diving. All equipment must be
cleaned for use with oxygen and then only used for nitrox. This includes
cylinders and regulators as well. Additionally the mixing and filling
processes require extreme care. The gas must be analyzed before use
and should be checked just prior to making the dive. An oxygen analyzer
must be used for this check. A reliable analyzer will cost several
hundred dollars. In light of the results of the dive table survey
conducted recently at IQ, I do not believe that sport divers are ready
to handle the complexities of table adjustments for nitrox. In short,
I think that for sport diving the possibilities for problems far out
weigh the benefits, and nitrox diving should be left to professional
divers.
--Frank J. Toal,
Jr., NAUI 10185; Orlando, FL
A. Emphatically
NO!! I teach mixed gas diving, including nitrox, at a commercial diving
school. I spend a minimum of 40 hours in the theory, mathematics,
and mechanisms of the subject in the classroom before we begin an
even longer practical module. Nitrox gas diving by far has the least
research and the fewest verifications of the no-decompression and
decompression schedules of all the possible gas mixes which we use
in the commercial diving industry. In an industry where decreasing
decompression time translates directly into more effective use of
the diver (read more bottom time for the same amount of money), we
still do not use nitrox diving to increase the no-decompression times
for a given depth. On the contrary, because increasing the oxygen
percentage causes adventure into the oxygen toxicity range, we set
the potential for a greater danger than that of decompression sickness.
And this is in an industry (offshore oilfield diving) where we have
full-time topside supervision and support and highly trained divers;
all working in their primary specialty of diving. A lot of this diving
is shallow--less than 80 fsw--and using no-decompression, repetitive
diving schedules.
Sport divers--recreational divers--would do well not to emulate or
try to venture into commercial diving areas. How would they mix their
gasses? How many instructors are qualified to teach such subjects
involving compressibility coefficients of various gasses; the real-gas
method of calculating partial pressures in a mixture versus the ideal-gas
method; calculations of and methods used to adjust percentage of mixes
(especially difficult in small cylinders such as used in scuba and
without precise test gages); establishment of no-decompression limits
and oxygen partial pressure/time limiting factors; etc. And once taught
to some varying level of competency, how are we to assure the students
will perform within the limitations once they are on their own? I
feel we are looking at "liability city" here.
We are treading dangerous ground. Sport diving should constrain itself
to just that and not venture into the realm of military combat diving
and commercial diving, no matter how exotic the latter two may seem.
--Jim Haynes, NAUI
2115; Houston, TX (Teaches at The Ocean Corporation. Has taught at
the USN Dive School, as a military advisor, semi- and closed-circuit
UBA diving to Greek attack swimmers. Has worked as a military EOD
and deep sea diver and supervisor, commercial diver, and offshore
diving supervisor. Has taught sport diving from skin through ITC Director,
and has been recipient of several NAUI Outstanding Service Awards.)
A. I understand
that nitrox will or should reduce the number of decompression sickness
accidents in sport diving. I am not convinced, however, that sport
divers will follow the rules any better than they do now. I am under
the impression that many of the DCS hits are a result of sport divers
pushing the limits and bending the rules.
Another concern is the availability of nitrox. What guidelines will
divers use when they make repetitive dives using air for one dive
and nitrox for another?
The question is; should NAUI offer a specialty training program for
using nitrox? I think we should get involved in training to insure
that sport divers have the necessary skills and knowledge to use nitrox.
We are the premier diving educators and we should be leading the development
of any training program that will help to make sport diving safer
and more enjoyable. It appears that nitrox is going to be used by
sport divers. NAUI needs to be involved with the development of safe
diver training for using nitrox.
We should learn a lesson from the alternate air source evolution.
It has been about 20 years since sport divers began attaching an additional
second stage on their regulators for air sharing underwater. NAUI
did not get involved in the development process, and consequently
the training and use of these life saving devices is not standardized.
Instructors still are unable to agree on the best methods for training
divers how to use alternate air sources.
I hope NAUI decides to lead the development of educational programs
for using nitrox and other sport diving innovations. Our role is "Safety
Through Education."
--Tom Hemphill,
NAUI 2491; Federal Way, WA
A. Breathing
gasses other than air have been used for underwater consumption long
before recreational diving became popular. These mixes have been applied
to commercial, science, and exploration dives for the very same reason
they are under consideration for the recreational industry today;
with appropriate management they will provide a greater degree of
safety and efficiency to the human diver underwater.
Perhaps our focus within NAUI should not be on the technology, but
rather on how it is to be used. In my opinion, the availability of
nitrox to the recreational community is inevitable. We should focus
instead on what component of this new technology we do wish to define
as recreational. No one will dispute that bandmask surface-supply
gas diving is outside the realm of recreational diving, but a well
managed alternative called hookah diving is a popular recreational
rendition of the same technology. The recreational diving community
has overcome and benefited from the introduction of many new technologies
(the LP inflator, alternate air source, buoyancy compensator, and
recently the dive computer) by carefully and appropriately applying
them to improve the safety and efficiency of its members.
NAUI has always stood for Safety Through Education, not ignorance
or restriction. Our membership should learn as much as possible about
this technology, encourage further research, and seek out appropriate
renditions of this and future technologies for the recreational community
we serve. History has taught us that if we fail to pursue new ideas,
we leave it to others to define them for us.
--Gregg
Stanton, PhD, NAUI ????; Tallahassee, FL(Director, Academic Diving
Program, Florida State University; and Research Diving Coordinator.
Has taught all levels of diving up to and including ITCs. Has conducted
nitrox and mixed gas workshops for the American Academy of Underwater
Sciences, and has authored many papers on various aspects of research
diving.)
A. Nitrox,
which is a mixed gas, has no place in sport diving. Mixed gas diving
requires extensive and highly specialized training that is not practical
for the sport diver. Mixed gas diving has many physiological effects
on the body that differ greatly from air diving and also require a
person to be in excellent physical condition in order to perform safely.
NAUI should not get involved in nitrox or any other mixed gas training.
Let the commercial divers dive where mixed gas is warranted. We have
a difficult time in training competent air divers, we do not need
the extra burden of training sport mixed gas divers.
--Patrick
Mark Cotter, NAUI Z7783; Carbondale, IL(Assistant Instructor at Bowling
Green State University. Graduate of the Commercial Diver Training
program at the Florida Institute of Technology.)
A. There is
nothing strange or exotic about nitrox. In fact, we have been breathing
a nitrogen-oxygen mixture (air = original nitrox) since birth. Until
recently, the use of a varied mixture of nitrogen and oxygen has primarily
been for military or scientific diving purposes. The National Oceanic
and Atmospheric Administration (NOAA) has been using nitrox safely
on scientific diving projects for over ten years. Nitrox is now entering
into use by certain segments of the sport diving community. The temptation
to use nitrox is understandable. It can appreciably increase bottom
time with a decreased risk of decompression sickness and, as a side
benefit, reduces the risk of nitrogen narcosis.
Any diver with a basic understanding of physics and a filler hose
adapted to connect between an oxygen cylinder and a dive tank can
change the nitrogen-oxygen ratio of their breathing mixture. Nitrox
tables are available (NOAA Diving Manual) in a form that most divers
can understand. The one essential ingredient missing is how to do
it safely. Nitrox mixers (dive shops, clubs, or individuals) need
to know the potential dangers of handling pure oxygen and that the
equipment used to transfer and hold pure oxygen has to be oxygen clean.
Nitrox divers must know the tolerable limits of increased partial
pressures of oxygen. These needs can only be met with a well organized
training program.
I personally believe that nitrox will be a standard breathing mixture
for sport divers in the not too distant future and hope that NAUI
is ready with a nitrox specialty training course to meet the demand.
--Ian
K. Workman, NAUI 4232; Gautier, MS(Unit Diving Supervisor for NOAA
Southeast Fisheries Center, and instructor for SeaSpace Dive Center.)
A. NAUI should
not offer a specialty in nitrox diving. At the moment there are no
special scuba cylinders for nitrox mixtures which does not make it
impossible for a diver to confuse a nitrox filled cylinder for an
air filled cylinder, or vise versa. The consequences of that small
mistake could be devastating. What happens when divers or stores do
not quite empty their nitrox filled tanks and carelessly refill them
with air for other divers or dives? What happens when a diver who
has used a mixed gas has a diving accident and needs hyperbaric treatment?
What are the assurances that the doctor will know exactly what percent
oxygen the mixture contained? How do we insure that the nitrox produced
by all the stores meets exact specifications (whatever those are),
and that their students are able to retain what they have learned
in a two or three day course enough to be safe (we have trouble enough
in getting them to drop a weight belt or read tables after a year)?
Is it worth the extreme liability it involves? We do not think so.
Our goal is to make diving safer, not to introduce "just another
way for divers to possibly get hurt."
--Walt
"Butch" Hendrick, NAUI 1724; Hurley, NY
--Andrea Zaferes, NAUI 10533
--George Safirowski, NAUI 8921L
--Walt "Sandy" Hendrick, NAUI ????
(All are instructors of Lifeguard Systems Inc. Butch Hendrick is a
past Director of NAUI, and recipient of the NAUI Outstanding Service
Award and the Leonard Greenstone Award, and author of Oxygen and the
Scuba Diver.)
A. Successfully
used by the National Oceanic and Atmospheric Administration (NOAA)
and an ever growing number of research institutions during the past
twenty years, nitrox's validity as a safe gas are beyond dispute.
The concerns of safety alone should dictate NAUI's policy: the lack
of professional, sanctioned training in the proper use of nitrox has
led some divers to adopt improper and dangerous methods of creating
oxygen/nitrogen mixtures. The motto "Safety Through Education"
can and should be applied to the use of nitrox.
Rather than stand by and watch divers engage in imprecise and dangerous
practices of gas mixing, NAUI should be blazing the trail in assisting
those divers who wish to become educated as to correct procedures
for mixing and using nitrox. By definition, a nitrox course must include
gas mixing information, which is NOT to say that the course will qualify
divers to mix their own gas. It is hoped that such information will
lead to the discontinuance of dangerous and incorrect mixing practices.
Safety factors, such as gas distribution and use during training,
can be addressed in the Standards and Procedures Manual. For example,
we may wish to designate nitrox distribution centers to ensure a valid
supply of legitimate gas. Because of possible oxygen toxicity complications
when using NOAA Nitrox I, we may wish to limit nitrox training dives
to areas where there is NO possibility of descending below 130 fsw.
Experienced divers who wish to use nitrox will not be (and are not)
discouraged from its use because a certifying agency will not sanction
it. Let us allow those with the experience and inclination to become
more knowledgeable about correct and incorrect uses of nitrox. In
this way, NAUI will further the advancement of safe recreational diving
and continue to be a leader in the field of sport diving.
--Bernie
Chowdhury, NAUI 10304; New York, NY(Teaches Openwater I to Advanced
classes and Deep Diving specialty courses for Pan-Aqua Diving, Inc.
Member of the International Association of Nitrox Divers.)
A. Breathing
gasses other than air have been used for underwater consumption long
before recreational diving became popular. These mixes have been applied
to commercial, science, and exploration dives for the very same reason
they are under consideration for the recreational industry today;
with appropriate management they will provide a greater degree of
safety and efficiency to the human diver underwater.
Perhaps our focus within NAUI should not be on the technology, but
rather on how it is to be used. In my opinion, the availability of
nitrox to the recreational community is inevitable. We should focus
instead on what component of this new technology we do wish to define
as recreational. No one will dispute that bandmask surface-supply
gas diving is outside the realm of recreational diving, but a well
managed alternative called hookah diving is a popular recreational
rendition of the same technology. The recreational diving community
has overcome and benefitted from the introduction of many new technologies
(the LP inflator, alternate air source, buoyancy compensator, and
recently the dive computer) by carefully and appropriately applying
them to improve the safety and efficiency of its members.
NAUI has always stood for Safety Through Education, not ignorance
or restriction. Our membership should learn as much as possible about
this technology, encourage further research, and seek out appropriate
renditions of this and future technologies for the recreational community
we serve. History has taught us that if we fail to pursue new ideas,
we leave it to others to define them for us.
--Gregg
Stanton, PhD, NAUI ????; Tallahassee, FL (Director, Academic Diving
Program, Florida State University; and Research Diving Coordinator.
Has taught all levels of diving up to and including ITCs. Has conducted
nitrox and mixed gas workshops for the American Academy of Underwater
Sciences, and has authored many papers on various aspects of research
diving.)
[NOTE: The
views expressed in this column are opinions held by the individual
members referenced, and are not those of NAUI or the editors of NDA
News.
