By Dr Blanche Andrews

The negative health effects of smoking are largely known. It is generally accepted that smoking and diving are two activities that are best not performed together.

Yet, for some, the habit is hard to break. Statistics reveal that 16.4% of South Africans are smokers. The number of scuba divers who smoke is unknown. For those divers who smoke or who have a dive buddy or instructor who smokes, it is worth being aware of the risks associated with smoking and diving.

Smoking can damage almost every part of the body, resulting in possible chronic health effects such as a stroke, blindness, gum infection, aortic rupture, heart disease, lung disease, hardening of the arteries, reduced fertility and an increased risk for hip fractures. At any age, mortality in smokers is between 40% and 80% higher than it is in non-smokers.

Smoking is closely associated with medical conditions involving the cardiovascular and respiratory systems such as impaired ciliary function, increased mucus production, persistent coughing, non-specific airway hyper-responsiveness (AHR) and decreased physical performance. AHR is the tendency for bronchial constriction due to certain substances. Bronchial constriction is the abnormal tightening of the airways that makes breathing more difficult. For a scuba diver with AHR, even the compressed air released from the cylinders (which is colder and dryer than normal air) may cause bronchial constriction. The same is true should the scuba diver with AHR inhale sea water or exert him-/herself. Numerous studies show that a high percentage of smokers have AHR. Add diving to the mix, and the result is that scuba divers are at an equal or greater risk than what asthma patients are while diving.

Physical activity over and above the norm requires that more oxygen be delivered to the muscles. Smokers’ oxygen uptake is compromised due to the strain of smoking on the lungs. This decreases the body’s reserve to cope with more demanding activities such as diving or even a strenuous walk to the sea while fully kitted or swimming against a current.

The cardiovascular system includes the heart and all the blood vessels working with the lungs to deliver oxygen to the other organs. The long-term effects of smoking on the cardiovascular system include an increased risk of atherosclerosis, thrombosis and high blood pressure. Even short-term exposure to cigarette smoke can cause blood vessels to narrow, and can impair the inert gas washout after a dive.

The Effect of Diving on your Body

Breathing effects
The respiratory system provides oxygen to the bloodstream and eliminates carbon dioxide. The effects on the lungs when diving include:

–       Decreased chest wall compliance as a result of the water pressure, wetsuit and gear

–       Decreased lung compliance and volume as a result of fluid shifts within the body

–       Increased density of the breathing gas as a result of increased pressure

–       Increased risk of barotrauma or lung injury as a result of pressure change

–       The lungs acting as a bubble trap

Heart effects

When a diver submerges, there is a central shift of the blood in the body. Other stressors affecting the cardiovascular function include exposure to cold, the increased partial pressure of oxygen and the increased work it takes to breathe. All of these effects increase the heart’s work rate.

Smoking & Diving: A Risky Business

The optimal functioning of one’s heart and lungs is essential to managing stressful situations while diving. It is also crucial that inert gas is sufficiently eliminated from one’s body when diving. The damage to the body associated with smoking results in inadequate gas exchange. This, together with the cardiovascular effects, impairs oxygen delivery as well as inert gas washout. A study on smoking and decompression illness (DCI) found an association between smoking and an increased severity of DCI. A significantly higher severity of DCI was found when comparing light smokers, heavy smokers and people who have never smoked before. Divers are also at an increased risk of acute bronchoconstriction as a result of AHR and lung barotrauma, which may occur simultaneously.

An important component of fitness to dive is being able to physically meet the demands of the many circumstances that could be presented on a dive. This ability is severely compromised when the body has been damaged by cigarette smoke.

If safer diving is our ultimate goal, quitting smoking should also be.

Don’t risk it

Smoking and diving is strongly discouraged. Those who do not smoke but have a buddy or instructor who does should also be aware of the risks. For those who have a true desire to quit, there is medication like bupropion (Zyban) and varenicline (Champix) that may offer significant relief. Obviously, medical interventions are not without cost or potential side-effects; in fact, it is strongly recommended that divers discontinue diving during the four to eight weeks while on medication. Still, the R400 to R600 for medication and the short-term sacrifice of not diving justifies the many long-term gains in health and financial savings of kicking the habit. If safer diving is our ultimate goal, quitting smoking should also be.

Good News for Ex-Smoker Divers

Many of the adverse effects associated with smoking are reversible after quitting smoking. The extent of recovery is influenced by the smoking history prior to quitting and the length of time after quitting. This serves as encouragement to those who are currently smoking, but who are considering quitting, or to ex-smokers wondering if it was worth kicking the habit. It is definitely worth it! The additional margin of safety that quitting smoking affords divers may well be compared to the conservative use of dive tables, and should be encouraged for the very same reasons.