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

Dent 1

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

Dent 2

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.

Dent 3

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

Dent 4

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

Dent 5

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

Dent 6

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

Dent 7

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

Dent 8

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

Dent 9

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

Dent 10

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

Dent 11

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

Dent 12

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)

Dent 13

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

Dent 14

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,

Dent 15

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.

Dent 16

“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.

Dent 17

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.

Dent 18

Dent 19