Emory Dent
Cosmin Ritivoiu
ENG 102
30 March 2014
The Chemistry of Safe, Healthy SCUBA
Today, nearly one hundred years after underwater diving
was first initiated, the waters of this world are teeming
with the presence of humans. For recreational and
occupational purposes, every year “…about 250,000 new divers
receive diving license[s] and more than seven million people
participate in scuba diving” (Azizi 21). However, most of
these divers, with similar ignorance and zeal that drove
divers in the nineteen hundreds to their grave, fail to
submit to scientific and medical principles, and are
unprepared to move forward, without hazard, with a fuller
understanding and enjoyment of their abilities. Thus, the
purpose of the research performed and cited in this paper
will be to inform and instruct ignorant recreational divers
about the chemical and physical occurrences, as well as the
medical hazards, that accompany the average SCUBA diver,
specifically when three different precautions, expounded
upon here in order of increasing harmful potential, are
overlooked and disregarded: physician consultation, ear and
sinus pressure, and rapid descent and ascent. Despite
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relatively infrequent accident reports, and huge
technological advances in SCUBA gear, many underwater
enthusiasts fail to follow these precautions, and thus their
enjoyable activity is dangerously depleted.
Many Chemical occurrences and medical hazards accompany
the average SCUBA diver, but these three, regularly
overlooked, will be discussed in this paper. As divers
gradually become comfortable and confident in this aquatic
environment, an entirely different environment than what
they are accustomed to, it is quite easy for them to begin
treating the wet atmosphere like that of their own dwelling,
and thus begin deviating from possessing a proper underwater
demeanor. These slight deviances, though they may seem
minor, can bring great discomfort and pain to the
scientifically uninformed diver, who can avoid many
unpleasant medical conditions through following these simple
guidelines.
The first, and seemingly least harmful precaution
overlooked, and many times never even considered, is that of
the diver informing their physician about their underwater
endeavors. Chemically and physically, life underwater varies
dramatically in comparison to life on land, and many
difficulties arise in seeking to safely combine the two. The
first difficulty to overcome is that of pressure. As seen in
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Table 1, water exerts an immense amount of pressure (The
Physics of SCUBA Diving):
Table 1. Pressure Difference and Increase in Water
According to Table 1, most humans experience life at around
one atmosphere unit of pressure, and can only, with
increasing elevation, experience noticeable effects from
pressure change at very high altitudes. However, when
altitude drops below that of sea level, far more drastic
pressure fluctuations take place and effect the SCUBA diver.
As also seen in Table 1, for every thirty-three feet of
descent underwater, about fifteen more pounds of pressure
are added per square inch. Thus, unlike being on land, only
short increments underwater can account for large chemical
and environmental changes. This is due to two unique
properties that water possesses: its density and
compressibility.
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Water is much more dense than air. This means that
water has more mass per unit volume than air and will
weigh more per unit volume as well. [Also,] Water is
uncompressible. This means that water under great
pressure (force per area) will have the same volume as
water under much less pressure. (The Physics of SCUBA
Diving)
With these two principles in mind, the underwater
environment of the SCUBA diver becomes more understandable.
Water is far denser, and thus its effect is far greater
than that of air, and can be experienced under very minor
altitude changes. For example, a human can experience a
pressure change in their inner ear from flying thousands of
feet in the air, or by simply swimming to the bottom of a
fairly shallow pool. Thus, this pressure aspect of a diver’s
watery environment can have a drastic effect on a sea-level-
dwelling human. Yet, in spite of this abnormal, and
potentially dangerous pressure increase, many fail to
include SCUBA in conversing with their doctors, and thus,
because of the diver’s carelessness, the physician is left
unaware. Such interactions with a medical advisor concerning
past and future diving escapades are not only beneficial for
a medical care provider, but through the benefits and
greater knowledge of the diver’s life underwater gained
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through these interactions, they may be able to, more
accurately, diagnose and deal with any health problems that
may arise. For example, the German Heart Institute in Berlin
reported a SCUBA-related event that demonstrates the
importance of such communication:
A 45-year-old man without cardiac risk factors was
referred to our hospital 6 days after suffering from an
inferior ST elevation myocardial infarction during a
scuba diving holiday in Tuscany. He had already made
seven eventless dives. Sixteen hours after the last
scuba dive, he complained about nausea and chest pain
while driving up a mountainous road. The pain increased
and he called the emergency service. (Schneeweis, Fleck,
and Gebker, 2224)
Had this man disregarded and failed to correlate and include
his underwater adventures with his mountaintop discomfort,
deeming his SCUBA fun unrelated to his chest pain, the
doctor’s diagnosis and crucial, time-dependant maneuvers
would have been hindered, greatly jeopardizing the life of
the diver. This crucial conversing that ought to take place
between the physician and the SCUBA-diving patient is
twofold.
First, the diver must be aware of, willing, and able to
communicate various vital aspects of their existence that
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have been effected by their watery activity. This includes
reciting past and future diving escapades, sharing details
about location, animal life interaction, water conditions,
and depth of descent. All such details ought to be taken
note of in the individual’s dive log, which can serve as a
vital reference tool for the medical professional’s use, if
need be. Also, any physical and mental abnormalities
experienced before, during, or after a dive should be
frequently voiced. Thus, when the diver is faithful on their
side of communication, the physician’s side of the twofold
conversing can, and will, take place.
Secondly, with the situational knowledge gained by the
diver’s detailed informing, the doctor on duty can be more
fully prepared to inform the diving patient concerning any
noticed health abnormalities. The Cleveland Clinic Journal
of Medicine provides a helpful list of reminders for doctors
to share with their scuba diving patients:
Assess your health prior to each dive. If you have
had a change in a chronic medical condition or need
medications in order to dive, you should not dive
without a medical reevaluation.
Do not fly less than 24 hours after a dive. This is
a general recommendation that is critical after
longer, deeper, or repetitive dives but should be
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applied if there is any uncertainty.
Do not dive until the symptoms of a previous injury
are resolved and you have been cleared to resume.
If you have developed air embolus or pulmonary
barotrauma on past dives, you need a full
evaluation before diving again to ensure that your
risk is not increased for further adverse events.
If unusual symptoms occur after diving, seek medical
care and evaluation immediately.
If you plan to leave the country to dive, you may be
required to bring supporting paperwork to confirm
your current health status. (McMullin 721)
In sharing these helpful reminders, acting upon the
patient’s informing remarks, doctors can remind their
patients of the chemical and physical differences the
underwater world possesses, and how to handle and enjoy them
correctly.
The second, slightly more hazard-inducing precaution
that divers too often overlook is concerning their ear and
sinus pressure. Failing to correlate the drastic pressure
differences as having an effect on their bodies, many divers
suffer greatly from disregarding these vital, air-filled
body cavities. In a recent journal article issued by the
Association of Otolaryngologists of India, a group of
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scientists from the United Kingdom provided helpful insights
in reference to this dilemma. In light of recent studies,
“80% of diving-related problems involve the head and neck
region and the most common in recreational divers are those
of the auditory system” (Auditory Complaints in Scuba
Divers: an Overview). Scientific study and medical records
confirm that this precaution is unheeded extensively, and
many of such experienced problems could be avoided by,
simply, a greater level of understanding and information in
the mind of the diver in regards to water pressure and how
our bodies respond to it.
Concerning pressure’s effect on the human body, Table 2
provides many more necessary, preliminary insights into the
pressures of the deep (Dive Theory - the Physics of Diving):
Table 2. Air Volume Change with Increased Pressure
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Looking specifically at the air volume example at the far
right of Table 2, a greater understanding of how water
pressure anatomically affects the diver can be gleamed. A
compartment of air, when brought underwater, experiences
compression and becomes smaller, due to air’s gaseous
ability to conform to the shape that its surroundings
induce. Then, as the compartment increases in altitude, the
air becomes less concentrated, and fills the empty space
that the lack of pressure creates. In the human body, this
varying pressure affects two major anatomical regions: the
ears and the sinuses. “The ear itself is a predominantly
air-filled cavity, causing a number of complications when
descending to increased hyperbaric [abnormal] pressures”
(Evens, Bardsley, and Manchaiah 71). Thus the ear,
predominantly the middle and inner ear regions, as well as
the sinuses, are air-filled cavities that aid in amplifying
auditory input and vocal output, as well as maintaining
balance and lightening the heavy human head.
Normally, the pressure-induced volume changes that the
air inside these body cavities undergo, when a diver
descends, have no negative effect on the human, because the
restricted air will simply return to its normal state of
spaciousness upon ascent. However, if a diver is in a state
of abnormal anatomical pressure, as experienced in
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congestion, cold or flu viruses, and infections of the ear
or sinus, the compaction of the air inside these tiny body
cavities is not equalized and uniform, and, as a result,
severe pressure-induced pain and even possibility of rupture
can arise. Whether or not the diver is not experiencing any
congestion or above-water pressure abnormalities, decided
action must be taken in avoiding these possible
discomforting moments, deemed barotraumas. Barotraumas are
injuries “caused by a change in air pressure, typically
affecting the ear or the lung” (“Barotrauma”), and can
affect a diver with or without the presence of previous
congestion or illness.
The air inside the cavities of the ear, especially that
of the middle ear, must be open and capable of holding air
during the duration of the dive, especially upon descent.
Thus, a practice called the Valsalva maneuver is performed
and encouraged in the SCUBA diving realm, in order to avoid
most of these complications:
The most frequently encountered target of barotrauma in
diving is the middle ear. On descent divers will
normally “clear their ears,” compensating for the
volume changes in the middle ear by encouraging gas to
pass along the Eustachian tube. A swallowing movement
or a gentle valsalva manoeuvre [sic] with the glottis
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open and the nostrils occluded is normally sufficient
to achieve this. (Benton, Glover 249)
As the diver descends, their goal in performing the Valsalva
is to allow for the entry of air throughout the ear,
preventing other cavities, like the Eustachian tube, from
being pinched off, and thus inhibiting excessive pressure
buildup in one cavity, and little to no air in others. That
is why the Valsalva is referred to as equalization, because
by performing it, the diver is ensuring that each ear canal
and cavity possesses its rightful capacity of air, so that,
upon ascent, the expanded air volumes will return to normal,
instead of causing unnecessary discomfort or rupturing.
Simply, the maneuver consists of closing the nose and mouth,
and, very lightly, attempting to blow air through the
nostrils. This quick and easy diving protocol is vital in
ensuring good health and well being, as well as a sense of
enjoyment after the dive is completed.
The next slighted, precaution, possessing the greatest
harmful potential, that is crucial in safe SCUBA is that of
rapid ascent and descent. In light of this issue, the words
of Peter Turla, president of the National Management
Institute, are highly applicable: “It’s better to do the
right thing slowly than the wrong thing quickly” (Time
Management Quotes and Sayings). Thus, in order to rightly
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ascend and descend, the diver must be aware of the changes
that are taking place in their surrounding aquatic
atmosphere, and how it affects their physical and mental
well-being.
Nearly eighty percent of the air humans breathe is made
up of nitrogen gas, which is partially utilized for various
body functions and processes. The percentage that is not
utilized is expelled through different areas of body tissue,
thus avoiding unnecessary buildup. A NewsRX article further
explains this phenomenon:
As you go about your day-to-day activities, tiny
bubbles of nitrogen come and go inside your tissues.
This is not a problem unless you happen to experience
large changes in ambient pressure, such as those
encountered by scuba divers and astronauts. (Nitrogen
1)
Humans are constantly expelling this excess nitrogen through
an occurrence divers call “off-gassing,” and are thus
preventing the harmful effects an excess concentration and
saturation of nitrogen can bring. However, as the article
stated, problems begin to arise as the diver ventures into
the high-pressured deep. As the pressure water exerts upon
the human body increases, with decreasing, sub-sea-level
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altitude, the body’s ability to freely expel the excess
nitrogen through its tissues is gradually restricted.
Instead of releasing its nitrogen into a low-pressure, air-
filled environment, the body is now tasked with trying to do
so under double, or maybe even triple the pressure in which
it normally performs the duty. Thus, with increasing depth
and pressure, the body becomes more and more nitrogen-
saturated. For short periods of time, this occurrence isn’t
harmful, because upon performing a controlled, gradual
ascent, the diver will slowly re-gain their off-gassing
ability. However, with a limited supply of air at hand, the
diver cannot spend more time in slow ascent, by means of
allowing their body to return to a state of normal nitrogen
concentration, than what their tanks can give. Thus, in
ascending and descending, SCUBA divers must execute careful
planning and performance, or various nitrogen-induced
discomforts can result.
For divers who haven’t yet undergone the effects of
major nitrogen buildup during descent, rapid descent can
induce a rather peculiar neurological response:
The nitrogen in air at increased pressure, for
instance, can have effects on cognition similar to
alcohol intoxication, known as narcosis. (Benton,
Glover 241)
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Inducing a neurological, hallucinogenic-like response, the
“narked” diver may begin to act uncontrollably, performing
maneuvers that fail to register in their memory, and thus
cannot be recalled upon emerging from the experience.
Although this occurrence may be dangerous at times, it
mostly results in harmless, and slightly humorous, actions
of peculiarity. However, whether or not nitrogen narcosis is
experienced, the excessive buildup of this gas must
eventually be released in such a way as to allow the body to
return to its initial concentration level.
As stated previously, the method the body possesses to
release excess nitrogen is referred to as “off-gassing,”
which functions far slower in water than in air. Thus,
during ascent, the recreational diver must rise slowly,
pausing for a fifteen-minute “safety stop” at a depth of
fifteen feet, in order to ensure complete removal of excess,
potentially harmful nitrogen. Despite these advised
precautionary measures, however, some divers fail to spend
enough time in ascension, and thus run the risk of suffering
from, possibly, the greatest SCUBA-induced physical
disorder, described in the following article:
During decompression sickness (DCS) inert gas (usually
nitrogen) supersaturation results in the formation of
intravascular bubbles which can lead to venous gas
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emboli (VGE). (Lambrechts, Pontier, Mazur, Buzzacott,
Morin, Wang, Theron and Guerrero 1)
Decompression sickness, in its many forms, is the result of
excess gas concentration in various parts of the body,
seeking release into the atmosphere. Wherever abnormal
amounts of nitrogen may be present, upon the body’s return
to the surface, its gaseous properties cause its molecules
to group together and create a bulging air embolism. This
drastically discomforting disorder can be experienced almost
anywhere in the body, but most commonly occurs on body
tissues that face upwards, like the neck and shoulders, due
to the nitrogen’s rising effect. From bleeding eyes to
ruptured lungs, these embolisms induced by decompression
sickness have wreaked havoc in the lives of many an
uninformed diver.
Recreational SCUBA diving provides for its participants
an incomparable experience that many fail to embrace.
However, as discussed throughout this paper, if, during this
fascinating inflow, a SCUBA participant is uninformed or
forgetful of the chemical and physical changes taking place
about them, great pain and discomfort can result. By failing
to heed the precautions of consulting their physician,
taking account of ear and sinus pressure, and carefully
ascending and descending, a simple dive, or even a life,
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could be ruined. Thus, by simply understanding and heeding
the chemical and physical occurrences looming about, the
diver may ensure safe, healthy SCUBA for years to come.
Works Cited:
Azizi, Mohammad-Hossein. “Ear Disorders in Scuba Divers.”
The International Journal of Occupational and Environmental
Medicine. Volume 2 Number 1. 20-25. Web. Jan. 2011.
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“Barotrauma.” New Oxford American Dictionary. 2nd ed. 2005.
Baxter, David and Schmidt, Timothy. “Pressure.” The Physics
of Scuba Diving. Web. 2003.
Benton, P.J. and Glover, M.A. “Diving medicine.” Institute
of Naval Medicine. Travel Medicine and Infectious Disease.
2006. 238-254. Web. Sept. 2005.
“Dive Theory – the Physics of Diving.” PADI IDC Guide. Web.
2009.
Evens, Rachel A. Bardsley, Barry and Manchaiah, Vinaya K. C.
“Auditory Complaints in Scuba Divers: an Overview.” Indian
Journal of Otolaryngol Head and Neck Surgery. Association of
Otolaryngologists of India. January-March 2012. 71-77. Web.
Oct. 2011.
Lambrechts, Kate. Pontier, Jean-Michel. Mazur, Aleksandra.
Buzzacott, Peter. Morin, Jean. Wang, Qiong. Theron, Michael
and Guerrero, Francois. “Effect of decompression-induced bubble formation on highly trained divers microvascular
function.” Physiological Reports. Wiley Periodicals. 2013.
Volume 1 Issue 6. 1-10. Web. Oct. 2013.
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McMullin, Ann Marie. “Scuba Diving: What you and your
patients need to know.” Cleavland Clinic Journal of
Medicine. Volume 73 Number 8. 711-721. Web. Aug. 2006.
“Nitrogen; Report describes the physics of the bends.”
NewsRx. Proquest. 1-3. Web. Jul. 2010.
Schneeweis, Christopher. Fleck, Eckart and Gebker, Rolf.
“Myocardial infarction after scuba diving.” Department of
Internal Medicine/Cardiology, German Heart Institute Berlin,
Berlin, Germany. 2224. Web. Mar. 2012.
Turla, Peter. “Time Management Quotes and Sayings.” Time
Management Made Easy. Web. 2014.
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