of asthma on dive safety. Dive physicians have traditionally taken a very conservative approach to asthma in dive fitness assessments. Mention of the word “Asthma” and potential divers were ejected from the surgery faster than you could say, “but it wasn’t serious and it’s gone away now”
More recently, some dive physicians have begun to take a more liberal, informed consent approach in assessing previous or mild asthmatics for diving. Some ex-sufferers previously prevented from diving can now dive, after making an informed choice about the possible risks. To understand this, it is first necessary to understand what asthma actually is. Asthma is a condition affecting medium to small airways in the lungs. In asthmatics, these airways are prone to narrowing, which impedes the flow of air into and, in particular, out of the small air sacs (alveoli) where gas exchange occurs. The trigger for these events is often an allergic response to a specific stimulus.
Some asthmatics also respond to physical stimuli such as exercise or a change from breathing warm air to cold air. The result is that the patient feels short of breath and there may be an audible wheeze due to airway narrowing which can cause severe breathing difficulty, which in severe cases, can certainly be fatal. One of the biggest problems in discussing asthma, and this is particularly true when discussing asthma in the context of diving, is that the spectrum of severity is extraordinarily wide.
There are three main concerns about asthma and diving. First, asthma may make divers more likely to suffer a dive-related illness. We are all taught that the most important rule in