Asthma and Diving Risk

What Does the Science Show?

Asthma and Diving Risk
Asthma and Diving Risk. Getty Images

The topic of asthma and diving risk has been debated for some time without any definitive answers for doctors or patients.

There is certainly some risk. DAN statistics reveal that several diving related deaths involved patients with asthma. However, examination of the accident reports did not allow a conclusion as to whether asthma played a role or was merely a coincidental finding.

There is a concern that the compressed air you breathe in underwater might act as a trigger for an asthma attack.

It might be the cold, compressed air coming from the tank acting as a trigger or some other allergen that makes its way into your air system from inside the tank. Additionally, there is a concern about what might happen to the asthmatic if the regulator comes out and you aspirate some amount of sea water.

Additionally, breathing at depth causes two other changes related to the pathophysiology of asthma. Increased resistance from breathing through the regulator or mouth piece and external pressure placed on the chest under water theoretically may increase narrowing of the airways. Airway narrowing could cause retention of gas as you ascend from depth and result in a collapsed lung or pulmonary embolism.

If asthma is not optimally controlled there is a concern that expanding gases will be trapped in the lungs and possibly lead to a ruptured lung.

Self Reported Divers Experience

An older survey of 104 asthmatic divers found this group preformed more than 12,000 dives and 2 cases of decompression sickness was reported from one diver.

Neuman et al. reported on the experience of nearly 700 divers and more than 6000 dives. In the 5% of divers in this cohort with asthma, there were no reports of decompression sickness or other serous diving complications.

Asthma Diving Complications

After drowning, arterial gas embolism or AGE is the next most common injury associated with diving.

AGE is when air gets into the blood system and travels to an organ like the brain and causes symptoms and damage similar to a stroke. AGE results from small tears in the lung from expansion as you ascend and the volume of gas increases.

Deaths have been reported in about 1 in 100,000 dives and injuries at a rate of 10–20 per 100,000 dives. In the DAN database, the risk of AGE among current asthmatic divers for AGE is twice that of non asthmatics, but does not reach statistical significance.

Recommendations Vary By Country And Organizations

In England, there are no restrictions of well controlled asthmatics provided bronchodilators have not been needed in the 24 hours before a dive and you do not have cold, exercise, or emotional induced asthma.

Australia is at the other end of the spectrum and requires divers to have a spirometry test to exclude asthma before becoming certified.

Most organizations in the United States require you to complete a medical clearance form and may require medical clearance from your doctor.


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  2. Tetzlaff K, Muth CM, Waldhauser LK. A review of asthma and SCUBA diving. Journal of Asthma 2002; 39(70: 557–566.
  3. Ivkovic D, Markovic M, Todorovic BS et al. Effect of a single pool dive on pulmonary function in asthmatic and non-asthmatic divers. Diving and Hyperbaric Medicine 2012; 42 (2): 72–77.
  4. Davies MJ, Fisher LH, Chegini S, Craog TJ. Asthma and the Diver.Clinical Reviews in Allergy & Immunology 2005; 29:131–138.

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