Saturday, June 5, 2010

Dangers of Scuba Diving

Too often I have seen enthusiastic people rush into the world of diving without a full knowledge of the dangers. Ofcourse it is impossible to know everything but just being aware of the dangers and right procedures will make a considerable difference into more successful, enjoyable, safe and accident free diving.

Of course the dangers are almost unlimited from hitting your head when changing level (Always look or feel where you go, even when it's up.) or surfacing on a boat running over you knocking you unconscious, or the motor rotor chewing you up when backing up on top of you, to getting maimed on corals by huge waves, to your equipment breaking down or malfunctioning.

Ofcourse it is better to live and try to understand life than not to live at all, so I follow the same code as when driving a car:

Rather drive freely, being aware of the possibility of an elk crossing the road, rather than driving your whole life slowly afraid to hit an elk just to hit an elk at some point anyway and die, or worse yet, not driving at all. Whatever we do, we will die, whether in bed or doing what we love.

Ofcourse I cannot possibly mention everything, but first I am going to start with the most common diver's diseases and what makes them happen.

Most common way to dive in Recreational Scuba Diving as opposed to Technical Diving is with normal compressed air of 79% Nitrogen [N] and 21% Oxygen [O] (specifically 78.08% nitrogen [N], 20.95% oxygen [N], 0.93% argon [Ar], 0.038% carbon dioxide [CO2]).

Some recreational diving use Enriched Air, which contains more Oxygen, sometimes called NitrOx. Technical diving usually uses more than one tank, more than one mix of breathing gases, and it can use Helium [He] to replace Nitrogen.


Decompression Sickness, DCS, The Bends, Caisson Disease

Water surface, where air and water meet in sea level, where the whole weight of air rests on the water right from space to the surface of the water is called one Atmosphereor 1 atm or 1 bar. 10 meters below the surface the pressure of the water roughly equals two atmospheres, adding one atmosphere every 10 metres. 50 meters equaling 6 atmospheres.

At surface only a certain amount of nitrogen can be collected in your tissue, and no more can be collected. This state is called saturation. When descending down to 10 metres or 2 atmospheres, the amount of nitrogen that can be absorped by your tissue by your breathing is doubled, however the absorption is not instant.

When tissue can absorp more nitrogen, this state is called unsaturation. The degree of unsaturation specifies the amount of nitrogen that your tissue can bind.

When descending to for example 30 metres or 4 atmospheres and staying there so that your tissue gets saturated by nitrogen and then ascending, your tissue starts releasing the now excess nitrogen that can no longer be binded to your tissue. This state is called supersaturation.

If the accent is too fast, the releasing nitrogen released from tissue back to bloodstream has no time to dissolve, it will form together into small bubbles inside the veins. If the ascent is continued, the bubbles can no longer dissolve at all but will get bigger and bigger.

(Both due to the fact that it cannot be dissolved in this state and to the fact that it is was a gas under pressure and it will expand when the pressure is released due to ascending. X amount of gas ascending from 4 bar pressure in 30 metres or 4 atmospheres will expand 4 times [X x 4] when reaching the surface of 0 metres/1 bar/1 atm/1 atmosphere.)

Ascending from a depth too fast for nitrogen to dissolve, causing supersaturation and forming of bubbles into bloodstream will cause the condition called decompression sickness.

Regardless on the severty of the condition and the amount of nitrogen, decompression sickness is always a life threatening condition that requires immediate recompression, so that the nitrogen is again compressed and absorped, so that it can be dissolved.

(It has been reported from the bones of old professional divers that they contain hollow bubble holes, caused by expanded undissolved nitrogen.)

The wide array of symptoms for decompression sickness include; bending over into a little ball from pain, unconsciousness, joint pains, numbness, tingling, death. The bubbles will form into the joints and can go into arteries, heart and brain, causing unsonsciousness and death.

The first aid for decompression sickness is emergency oxygen (100%), administered immediately. The head of the victom must be kept low, and the victim must be transported into facilities with a decompression chamber immediately.

Decompression in water is not recommended due to the fact that it cannot be done safely or deep enough and the victim might lose consciousness any second and suffocate in water. Decompressing in only 1 atm might not produce any real relief for the condition.



Other Decompression Illnesses or DCI

Holding breath causing DCI or Tissue Damage

When diving, one must breathe constantly, because a diver should be in a state of neutral buoyancy in mid breath, so holding empty lungs would cause the well balanced diver to sink and holding a breath would cause the diver to rise, thus allowing the pressure to become lighter and the air in the lungs to expand, causing the diver to rise further and faster and the air to expand more and faster, until eventually it will rip the lungs, or force its way into the bloodstream through the lungs, cause Decompression Sickness or severe tissue damage.

Equalization DCI or Tissue Damage

When descenting from the surface, the diver must constantly equalize his nasal and ear cavities to avoid damage and discomfort.

This equalization is done simply by making a swallowing motion with one's throat (no need to actually swallow), so that the ears are unlocked and the air is allowed to equalize. The feeling of pressure will slowly build when descending, but the equalization should be imminent, before any discomfort occurs.

If it is not possible, then ascent again, to a safely comfortable level of pressure and equalize again, ascending if any problem is encountered. To gently help equalization, the diver can turn his head from side to side, allowing the ears to open and the air to move.

However if the diver holds his nose and tries to blow into it, forcing the air to equalize, this can cause damage to the ear drum, or leave some cavity in the cheeks or the forehead unequalized.

Or if the diver is diving with a sickness and his cavities are blocked, he will be unable to equalize.

Or if the diver keeps descending, or trying to equalize at a level of pain or discomfort.

These mistakes can cause great damage to the cavity tissues and especially the ears.

The sudden rupture of an ear drum will instantly destabilize the diver and cause vertigo, where the diver will lose sense of direction and might choke on water(if the regulator is turned upside down, it can take in water, or the diver can panic or lose his regulator), or lose consciousness and drown.

The vertigo might cause the diver also to hold his breath or make him unaware of his depth, causing him to be sweeped to the surface, or further down, causing more tissue damage.

If in vertigo, water in your ears, you should hold on to a coral, or to the shoulder of your dive buddy and regain your sense of direction and situational awareness and calm your mind into the right action.

If the vertigo is not recovered or the discomfort doesn't stop, the dive should be aborted.

Reverse Block

However if a diver is diving with a flu/allergy, even if he is treating it with medication, and he forcefully equalizes, or even gets to equalize normally with no pain, he can be in deep trouble.

With equalized air cavities, the diver, willing to start ascent might have blocked airways and will be unable to equalize when trying to get back to the surface. In this situation one should alert his buddies and seek to descent a little and try to equalize again.

In bad situations a spare tank might be lowered for the diver trying to get back up. In extreme cases with short air supplies the lone diver might have to force equalization or break into the pain and forcing accent. This ofcourse will result in tissue and/or ear damage.

Trying to break the pain barrier by forcing oneself to ascent might cause severe damage and even unconsciousness and drowning.

Before trying, take your mask off and keep trying to blow your nose forcefully, trying to extract all the snot and clear your cavities. This might or might not help.

Oxygen Toxicity

Keeping in mind that everything matters, fresh or salt water, elevation of water surface from sea level and breathing gas compounds. Dive depth and time, pressure and saturation level, ascent speed and equalization, even exhaustion, alcohol, sickness and stress. There are a million factors and even the dive tables are just guesses for safe diving.

Nothing can guarantee that you wont get DCS or a DCI from diving "within the limits". These limits are just guessed, guessed by dive professionals, taken from the experiences of professional divers during the short history of diving. They are not calculated for your body type, mental health, physical health and condition in mind, or your dive environment or dive conditions in mind.

At certain depth/pressure oxygen becomes toxic to you. The depth/pressure varies. Oxygen toxicity might come at an unaware moment. It is a danger with risky Enriched Air diving. With safe compressed air diving within limits, oxygen exposure is not really an issue.

Oxygen partial pressure is calculated from the percentage of oxygen in the breathing gas mix, and the pressure in atmospheres. The deeper you dive, the higher oxygen partial pressure.

NitrOx diving has it's own computer tables for safety. Generally the depth is not as deep or the same as with air. With NitrOx you can generally stay in the shallow depths for a longer time and the higher amount of oxygen makes recovery easier. Diving deeper is more dangerous the more oxygen you have, and the deep part of a dive will be shorter or not as deep.

Crossing these tables might make your body reject the oxygen, causing violent convulsions and even unconsiousness. It might make you throw up violently and cause you to drown.

When encountered with any oxygen toxicity symptoms (visual disturbances, ear ringing or sounds, nausea, twiching of face, muscle spasms, irritability, restlessness, euphoria, anxiety, dizziness), the dive must be aborted immediately.

Prolonged exposure to high oxygen partial pressures can cause Pulmonary Oxygen Toxicity, or Lorraine-Smith Effect. Burning and irritating the lungs, causing the reduction of the vital capacity.


Gas Narcosis, Inert Gas Narcosis, Nitrogen Narcosis, Rapture of the Deep

Commonly called Nitrogen Narcosis, in Gas Narcosis also the other gases, such as argon, carbon dioxide and oxygen are equally or more narcotic than nitrogen. The depth where the gas narcosis occurs due to gases dissolving into yourblood and reaching your nervous system through your cardiovascular and respiratory systems, varies for each individual.

The effects of gas narcosis with compressed air can be felt in 30 metres, but for me it is 40-50 metres. It will also happen in decompression chamber as in water, it is the same compressed air in either place.

It will feel like complete drunkenness, except more complete, it deeply affects the nervous system.

The danger here is doing something foolish.

Keep your calm, have some fun but be aware of your depth, time and gauges. Keep a still, calm and clear mind. If this is not possible, then it's best to ascend.

The effects of gas narcosis gradually and immediately disappear as the pressure lessenes.


Safety Stops

In recreational diving, it is advised to stop the ascent as 5 metres and stay there for 3-5 minutes. Ofcourse you can make multi level safety stops, stopping for example at 15, remembering to ascend slowly, or to plan your dive multilevel, from deep to more shallow, staying at each level a preconsidered time and sticking to your plans.

Best to make the stop for atleast 5 minutes, and make sure you stop deep enough. If you accidentally ascend, then go back to 5 metres to complete your stop.


Surface Interval

Previous dive will considerably affect your next dive. Everything affects, nitrogen residue, the depth of previous dive, and the time spent on shore. Keep atleast 1 hour intervals, plan to dive deepest and longest dives first.


Ascent Rate

The recommendation for maximum ascent rate is 10m/min (30ft/min).

They do give exceptions 18m/min (60ft/min) for an ESA (Emergency Swimming Ascent) or for assisting an unconscious diver to the surface.

The slower the better. Consider a 6m/min ascent rate. The closer to surface you are, the slower you should ascend.

If you are without time, try counting "one thousand, two thousand", very slowly for each meter you ascend.

If you are without any gauges, they ascend slower than the tiniest bubbles leaking from your tank. And by slower I mean atleast half slower.

Remember safety stops.



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Now we have covered DCS and most DCI. I will only add a few tropical fish:

Kivikala eli Velhokala (Synanceia verrucosa) Stonefish

The stonefish is the worlds most poisonous fish.

It will lie on the bottom, looking like a rock. It has potent neurotoxins secreted from glands at the base of their needle-like dorsal fin spines. It has about 13 of these venomous spines.


Recommended treatments include using heat to the affected area and antivenom. Using hot water at a temperature no lower than 45 degrees celsius, applied to the injured area has been found to destroy stonefish venom, and causes minimal discomfort to the victim. For more extreme cases, antivenom is to be used.

However this fish contains neurotoxin that will paralyze the respiratory systems, so death can be imminent. Whatever happens, keep calm and get treatment.

Siipisimput ja Skorpionikalat (Scorpaenidae) Lionfishes and Scorpion fishes

Siipisimppu (Pterois volitans) Red Lionfish

These fishes also have venomous spines, instead of being immobile however, these small predatory fishes are fearless and move alone or in vast numbers.


Don't get too close to one or it might be agitated and charge at you.

There have been no known fatalities caused by lionfish stings but they are reportedly extremely painful.

The treatment is similar to stone fish, hot water.


Titaanisäppikala (Balistoides viridescens) Titan Triggerfish

Titan triggerfish is the largest of the triggerfish species and can grow up to 75 cm in length (30 inches).  It feeds on shellfish, urchins, crustaceans and coral.


This fish will go completely berserk during nesting time, and it will chase and seek to bite all divers near it's territory.

Try to avoid, but if one is "dive bombing" you like a stuka, then turn your fins at it, and swim away while it retreats for it's next attack and repeat until you are safe.


Sinirengastursas (Hapalochlaena) Blue-Ringed Octopus

These extremely small (size of a golf ball) and extremely hard to spot, fearless animals are extremely poisonous. I came across one in Borneo, it was plain in sight, hard to spot though!, and sneaking it's way right towards me.


The venom of the blue ring is extremely potent, containing tetrodotoxin, 5-hydroxytryptamine, hyaluronidase, tyramine, histamine, tryptamine, octopamine, taurine, acetylcholine, and dopamine.

There is no blue-ringed octopus antivenin available.

The blue-ringed octopus is currently one of the most dangerous known sea creatures and, despite its small size, the blue-ringed octopus carries enough poison to kill 26 adult humans within minutes.

If bitten by this octopus, you are generally screwed. If the victim becomes paralyzed unterwater, grab him from behind holding his regulator in place and make an emergency ascent.

First aid treatment is pressure on the wound and rescue breathing. It is essential, if rescue breathing is required, that it be continued until the victim begins to breathe, which may be some hours. Hospital treatment involves respiratory assistance until the toxin is washed out of the body.

Victims who live through the first 24 hours generally go on to make a complete recovery.


Meduusat (superorder Selachimorpha) Jellyfishes

All jellyfish sting their prey using nematocysts, but the nematocysts of only some jellyfish species cause an adverse reaction in humans. Touching, or being touched by a jellyfish can be very uncomfortable, sometimes requiring medical assistance, but in many cases humans have no response to the contact.

Because of the wide variation in response to jellyfish stings, from no effect to death, it is wisest not to contact jellyfish with bare skin. Even beached and dying jellyfish can still sting, when poked and prodded.


Treatment: use gloves or sticks to remove and scrape off any stingers.

Vinegar (3 to 10% aqueous acetic acid) should be applied for box jellyfish (Cubozoa) stings. Vinegar, however, is not recommended for Portuguese Man o' War (Physalia physalis) stings.

Salt water may also be used in case vinegar is not readily available. Fresh water should not be used if the sting occurred in salt water, as a change in tonicity can cause the release of additional venom. Rubbing the wound, or using alcohol, spirits, ammonia, or urine will encourage the release of venom and should be avoided.

A strange but effective method of treatment of stings is meat tenderizer which efficiently removes the nematocysts.

A shower or bath as hot as can be tolerated can neutralize stings. However, if hypothermia is suspected this method may cause other serious complications.

The stinging cells cannot be removed by simply removing the tentacles. Clearing the area of jelly, tentacles, and wetness will disable further nematocyst firing. First aid providers should be careful to use gloves or another readily available barrier device to prevent personal injury, and to follow standard universal precautions. After large pieces of the jellyfish are removed, shaving cream may be applied to the area and a knife edge, safety razor, or credit card may be used to take away any remaining nematocysts.

Beyond initial first aid, antihistamines such as diphenhydramine (Benadryl) may be used to control skin irritation (pruritus). To remove the venom in the skin, apply a paste of baking soda and water and apply a cloth covering on the sting. If possible, reapply paste every 15–20 minutes. Ice can be applied to stop the spread of venom until either of these is available.

Merisiilit (Echinoidea) Sea Urchins

Sea ruchings are smiky balls that live in the bottom, usually in large colonies. THey have long spikes and they use the shorter bottom spikes with suckers to walk along hte bottom.

It is possible to lift on up by holding one of the fragile spikes, and place it to walk on your hand. Take care not to break any of it's spikes though.

It will try to spin the other spikes at you, but they will not hurt if there is no direct pressure involved. It can only wave the spikes horizontally in circles.


If you step on or directly hit your body into a sea urchin, the  hollow fragile tubular spikes will pierce yoru skin and break inside of you. This is very painful and the spikes are hard to impossible to remove, because they will break into fragments.

Some spines are poisonous, you can try to neutralize the sting with hot water and then use ice.


Sharks (superorder Selachimorpha)

Sharks are divided into a lot of groups. Some dangerous, some not. However it is possible to confont any of them and not get eaten or injured. Humans are not their first choice of nutrition.

Reef sharks are generally harmless, it is the big pelagic hot blooded sharks that you need to be aware of. These big predators usually roam the open oceans, rest of the sharks usually stay deep, 30-600 meters below sea level, and come up only with big upward underwater currents, to feed on the fish that feed on the plankton moving in the water.

After the surge of water is gone, these packs of predators will vanish back into the deep like you never saw them.


Whatever shark you encounter, it is best to keep your distance and not make any sudden moves. If you have to hit one, do so on it's nose, a shark's nose is extremely sensitive.

However it is probably more curious than agressive. Bad for you, they usually explore new things by feeling it with their snout or even by sneaking a small bite, so let it be your camera, tank, or fin, and not your arm that the shark is feeling out.

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Obviously reading this note will make no one a diver, but certainly it won't make anyone a worse diver.

So in short: Make sure you have enough of working equipment and correct good quality breathing gas. Look where you go and stay in contact with your friends. Never panic, STOP-THINK-ACT. Dont force equalization. Keep aware of your depth, time and gas. Make sure you ascend slowly enough. Make sure you use dive tables and computers safely, making frequent and long enough safety stops. Don't touch anything. That wasn't very short, was it?

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