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Questions and Answers on
Physiology and Medical Aspects of Scuba Diving


Lawrence Martin, M.D. Copyright 1997


Buy the book
Scuba quiz
Myths & Misconceptions
Disclaimer & Invitation

Brief History of Diving
Recreational  Diving
The Respiratory System
Explanation of Pressure

Water & Physical Laws
Unequal Air Pressures
Decompression Sickness
Oxygen Therapy
Gas Pressure at Depth

Dive Tables & Computers
Stress & Diving
Non-air Gas Mixtures
Women & Diving
Medical Fitness for Diving
Asthma & Diving
The Great Debate

All About DAN
Scuba Training Agencies
Magazines & Newsletters
Books & Videos

Diving Odds N' Ends

Internet Links

Myths and Misconceptions

Some information in this book will no doubt challenge myths or misconceptions held by many recreational divers. For people who prefer to browse I have made a list of some common myths and misconceptions; they are in the form of statements, with sections where each subject is mentioned or discussed. Each of these statements is: 1) accepted as fact by many recreational divers (personal survey), and 2) either not true or there is no basis for believing it is true.

There was no scuba diving before invention of the aqua lung by Jacques Cousteau and Emil Gagnan in 1943. Section A

The maximum recreational diving depth of 130 feet is based on studies of divers at various depths. Section A

Recreational diving is 'no decompression' diving; the three minute safety stop is not a decompression stop. Section B

When diving with compressed air, the percentage of inhaled oxygen increases with depth. Section D

Inflation and deflation of the buoyancy compensator is the main method by which to achieve buoyancy control under water. Section E

The most venomous sea creature is the sea snake (or some snake) found in the Pacific Ocean.
Section E (Diving Odds n' Ends)

The great white shark can grow to over 30 feet in length. Section E (Diving Odds n' Ends)

Decompression sickness only occurs in divers who exceed the limits of the dive tables. Section G

Decompression sickness and decompression illness are the same. Section G

Decompression sickness is an entity easily distinguishable from arterial gas embolism. Section G

The main reason for having oxygen available at any dive site is to treat hypoxia (low oxygen) in dive accident victims.
Section H

Pure oxygen inhaled at sea level can cause seizures. Section H

The cause of shallow-water blackout in breath-hold divers is buildup of CO2 in the body. Section I

All sharks are known to attack humans. Section I (Diving Odds n' Ends)

Dive computers generally provide for safer diving than printed dive tables. Section J

All dive computers use essentially the same algorithm and give essentially the same dive times for a given depth. Section J

Nitrox allows dives deeper than the recreational depth limit of 130 feet. Section L

Women are more prone to decompression sickness than men. Section M

Women risk shark attack if they dive during their menstrual period. Section M

Diving while pregnant is safe for the fetus if the diver stays shallow (less than 33 fsw). Section M

Proper cooking of fish can prevent ciguatera food poisoning. Section M (Diving Odds n' Ends)

Most medical prohibitions to diving (e.g., for asthma, diabetes) are based on documented data or clinical experience.
Section N

Diabetes is a clear prohibition for scuba diving. Section N

Asthma is a clear prohibition for scuba diving. Section M

Asthmatics who dive can minimize risk by staying shallow (less than 33 fsw). Section M

Scuba diving is safe. Section P

Scuba diving is unsafe. Section P

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Last updated: 28/10/97