Since 1997
Asthma and Scuba Diving
by DAN Medical Team on June 23rd, 2016

My daughter has asthma, but it is controlled by medication. Can she learn to dive safely?

In general, asthma is a lung disorder in which there is a tendency for the muscle surrounding the bronchi (breathing tubes) to contract excessively, causing narrowing, or broncho-constriction. As a result, this causes increased breathing resistance, which can manifest as wheezing, chest "tightness", cough, or breathlessness. In asthmatics, broncho-constriction can be precipitated by exposure to allergens, noxious fumes, cold air, exercise or respiratory infections such as a "cold". People with asthma may experience broncho-constriction due to more than one of these factors, but many asthmatics will experience a measurable increase in breathing resistance after exposure to any one or several of them. The increase in breathing resistance caused by bronchial narrowing may be compounded by the accumulation of mucus within the airways. 
​Serious potential risks may make scuba diving, which is often performed in isolated locations and far from competent medical care, an unwise elective sport for an individual with asthma. There are primarily two issues.
  • During scuba diving the diver experiences a reduction in breathing capacity due to the effects of immersion and an increase in breathing resistance caused by the higher gas density at depth. At 33-feet underwater, the maximum breathing capacity of a normal scuba diver is only 70-percent of the surface value. At 100-feet underwater, this reduction is approximately 50-percent. If, for example, a diver’s breathing capacity is already reduced because of asthma, there may not be sufficient reserve to accommodate the required increase demanded by exertion.
  • Both narrowing of the bronchi and excessive mucus production can inhibit exhalation of air during ascent, and could predispose the diver to pulmonary barotrauma leading to pneumothorax, pneumo-mediastinum and/or arterial gas embolism.
For these reasons, physicians trained in diving medicine have traditionally recommended that people with asthma should never dive. However, a consensus of experts at a 1995 workshop held under the auspices of the Undersea and Hyperbaric Medical Society (UHMS) proposed more liberal guidelines. Essentially, the UHMS workshop panel felt that the risk of diving is probably acceptable if, the diving candidate with some asthmatic ‘history’ demonstrates normal pulmonary function at rest (FVC, mid-expiratory flow, FEV1, FEF 25-75) and then again after strenuous exercise. It was also concluded that the degree of competency in making a medical assessment of diving fitness is enhanced if the examining doctor has relevant knowledge or experience of the diving environment and its associated hazards.

It is important to note that asthma severity can wax and wane. Symptoms may worsen for 4-6 weeks after a "cold" or during certain seasons (for example in response to high levels of pollen in the air.) Therefore, even if a person with asthma fulfils the criteria listed above, diving is not recommended unless the diver is free of respiratory symptoms before each dive. 

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Rachelle - October 15th, 2016 at 1:43 AM
Hi. I was diagnosed with asthma when i was very young and have lived with it for many years. I am not medically trained at all and the severity of asthma will obviously differ for people. I have been diving for approximately 6 years now and am happy to say that my asthma has never limited me in this. I have no idea what it's called (again, no medical training) but when i did my medical before obtaining my diving certification i was given a device that i can use before a dive to test my own lung capacity at that point in time. It's simply a device that you blow into with a marker moving up and down on a gauge indicating lung capacity. The doctor recommended a minimum level of capacity that, if not reached, to refrain from diving on the day but, if above, to go ahead. I have never had any challenges diving.
I don't want you to endanger your daughter because of one opinion but i know there are people suffering from asthma that dive and have done so safely. I always brief my buddy about my condition and if my breathing feels strained i abort my dive.
I hope this helped :)
Dr. Jack Meintjes - October 20th, 2016 at 1:46 AM
Rachelle, thanks for this valuable comment. You are indeed correct that a number of people with asthma are diving without problems. We currently know enough about asthma that we can with reasonable probability predict whether you would be able to dive safely or not. The device you are referring to is called a "Peak Flow Meter", and is very useful in managing asthma in general (not only for diving). There is a specific procedure to use a Peak Flow Meter correctly, and I am going to write an article that explains this in detail for one of the next installments of the Alert Diver magazine. It should highlight the procedure to determine (1) whether your asthma is well controlled or not and (2) how to determine what your "minimum value" should be and (3) how to use the device in relation to diving...
Rudi - October 15th, 2016 at 12:57 PM
I also suffer from asthma, more specifically exercise induced asthma. With my doctor's help, we have been keeping it under control up to the extent where I cycle and dive without any issues. Off course each patient has his or her own unique situation, so you need to work closely with your doctor and more importantly you ahould know your body. As stated by Rachelle, brief your buddy about your asthma and also the dm and skipper. As an additional safety precaution, I take my inhaler along and leave it with the skipper.

I have also heard about underwater inhalers, but I have not done any research on them.
The DAN team - October 17th, 2016 at 4:59 AM
Rachelle & Rudi we are pleased that you took the time to comment on the blog post. However we feel that your comments will be best addressed in person via our hotline. You can contact the DAN hotline toll-free in South Africa on 0800 020 111 or internationally on 27 828 10 60. Alternatively you can email your contact phone number to the DAN medic on call to In the meantime you can listen to the Asthma & Diving audio podcast via the DAN You Tube channel. You can use this link to access the podcast - You can also view the video podcast using the following link -
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