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Website home>Newsletters>June 2013>Smoking & Diving

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Smoking and Diving

Let's pretend that there is no knowledge out there about the negative health effects of smoking and forget that smokers have all but become social pariahs in today's polite society. This article is not meant as an anti-smoking tirade. Rather, we are fascinated by the number of divers and dive professionals who do smoke. Here we explore this unusual relationship.

For the moment, let's adopt a 1940's attitude: lots of people smoke, it is socially acceptable for men and women and hey, it even makes you look pretty cool, especially if you can blow smoke rings! Now let's throw scuba diving into the equation - is it still OK? Let's find out ...

Lots of Divers Smoke

There is no empirical data on the proportion of divers who smoke, but from our experience there are a lot who do partake. Certainly a lot of divemasters and instructors smoke. Why is this?

There could be a number of factors. They have a lot of spare time. They are also with people on holiday who are treating themselves to a pleasurable experience. Perhaps they feel that smoking is a pleasurable experience that they do not wish to deny themselves in this atmosphere.

They may also be surrounded by crew who smoke. This is particularly true in parts of the world where cigarettes are cheap and there have not been effective governmental steps to discourage it. In Indonesia, 2 out 3 men from a population of over 237 million smoke. There are no rules preventing the sale of cigarettes (in packs or singles) to minors so lots of Indonesian school children smoke. This videoOpens in a new window of an Indonesian toddler puffing away) shocked the world but Indonesians simply gave a collective shrug (and lit up another clove flavoured ciggie).

There persists an unfortunate school of macho thought when it comes to diving. Some divers think speed of gearing up, depth of diving, laddish joking and obsessing over seeing predators like sharks are all part of the fun. Smoking still has macho connotations in the minds of some and the denial of ill-effects of smoking can be part of that machismo. Check out these snippets from an online scuba forum on the subject:

"(Divers) ... that will light a freshie on the way into the water, and suck on it all the way out during the surface swim. When they reach the drop spot, they hang for a minute while they finish it, and then as soon as it's about to burn their gloves, they take one last fiberglass-rich pull off that bitch and flick it (of course, into the water)... then they stuff their reg in and drop. Literally, their first 2 sets of exhaled bubbles are 'smoking' when they pop on the surface."

"When I first got certified in '99 my OW Scuba Instructor in Hawaii was telling us that smokers make better SCUBA divers because your lungs are used to less air and your tank consumption is better than a non-smoker."

Limitations of Certain Smokers

Smoking has an effect. While 1 drunken cigarette every month at a party isn't likely to have huge consequences, a regular and/or heavy smoker is going to feel some effects in day to day life. What are the effects we all know about?

  • Smoking negatively affects your breathing. You are more likely to get out of breath more easily since your lung capacity is decreased. Controlled breathing, even in adverse conditions, is key to safe and enjoyable diving.
  • We all know the sound of a hackle-raising smoker's cough. The rattling is mucous which sometimes doesn't dislodge too easily, as evidenced by an ongoing coughing fit. Having one of these underwater is not too pleasant.
  • Nicotine dependency. There is nothing worse for a smoker than to have their cigarettes out of reach. You don't want to be fidgety and thinking about your smokes when you are at 45 metres in current with equipment concerns.
  • High blood pressure is a condition that no one wants since it can lead to all manner of emergency scenarios. They say worse things happen at sea; under it can be a pretty bad place for an emergency health scenario too. Smoking raises blood pressure.
  • Acid reflux is something that turns a pleasant moment underwater into a period of pain and no little danger. Smoking is a major contributor to acid reflux. That horrible burning swirling feeling of gastric acid making its way up the oesophagus and burning its sensitive lining is nasty at the best of times. For it to be happening underwater, not only spoils the moment, but can also be a potentially dangerous distraction as it requires all your focus just to suppress the discomfort.

The Science of Diving

We all know something of the science of diving: How breathing compressed air causes nitrogen to become absorbed into the blood. This is why we have to do safety stops to allow the nitrogen to come out of our blood slowly. If we ascend too quickly we might risk decompression sickness. A very quick ascent also puts us in danger of a lung over-expansion injury. We also know of the mammalian diving reflex and how that affects the heart.

How does smoking affect these scenarios?

Gas exchange

Most divers understand the science of what happens when you are breathing compressed air (or nitrox) under the increased pressure present underwater. When it comes to decompression illnesses, a lot depends on the particular physiology of the diver. 2 divers might experience the very same depth, conditions, challenges and ascent speed, yet while one suffers no adverse consequences, the other might suffer serious medical complications.

While this might be true if the 2 are both smokers or both non-smokers, there are some effects of smoking that play scientifically verifiable roles in the critical area of human physiology that is at issue in this scenario.

  • Haemoglobin, which we rely on to absorb oxygen into our system, in fact has a higher affinity for carbon monoxide so will more readily combine with that if it is present. Smokers have higher levels of carboxyhaemoglobin and this can lead to hypoxia, intolerance to exercise and higher levels of lactic acid.
  • The higher levels of lactic acid and carbon dioxide that smokers have are associated with promoting the growth of micronuclei into real bubbles.
  • Smoking contributes to vasoconstriction which reduces the body's ability to off-gas efficiently, resulting in a higher risk of decompression sickness.
  • Smoking plays a role in platelet aggregation which is something that raises the risk and severity of decompression sickness. Because of the lower levels of transport of oxygen by haemoglobin, smokers tend to have a higher red blood cell count as more are needed to do the same job. This makes the blood more viscous which impairs off-gassing as flow to the peripheries is reduced.

Lung over-expansion

Smoking damages your alveoli which causes your lungs to lose their elasticity. Inelastic lungs carry a much greater risk of lung over-expansion injuries like arterial gas embolism or pulmonary barotrauma.

Mammalian diving reflex and smoking

One of the physiological changes we experience when diving is the mammalian diving reflex. This means that while diving, the human heart is put under quite a strain. This one reflex explains why you hear so much about numerous heart attacks underwater. Smokers have a higher risk of heart attack than non-smokers. It is quite scary to consider that the combination of smoking and the mammalian diving reflex could combine to be the thing that carries you off.

Consideration for Others

We don't want to be killjoys. If you love to smoke (or think you do) then go ahead but please spare a thought for those who don't smoke. Remember that smoke to them is 10 times more horrible than it is to you. You are used to it as a necessary part of smoking; they might not be. Try to adhere to a few rules of decency: Stay in designated smoking areas; try to stay downwind of non-smokers; dispose of butts correctly.

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