FAQ: Can I scuba dive with asthma?

All your asthma and diving-related questions answered by an expert

Divers with asthma should find out more about the link between the medical condition and diving before getting certified

Asthma and diving has been the subject of debate for years and until today, there is no firm consensus for recreational diving. However, it is generally agreed that asthma does present increased health risks to the diver. If you have asthma, you probably have a bunch of questions going through your head, especially if you’re a new diver, so here are some of the answers you’ve been looking for.

Q: What is asthma?

A: Asthma is a condition of hypersensitivity of the small airways within the lungs (bronchioles) to certain inspired allergens which trigger off sudden narrowing of the airways. This results in airway obstruction, making it harder for the asthmatic to breathe out. The asthmatic will have symptoms classically described as difficulty breathing, chest tightness, wheezing and cough.

Q: What might happen if I have an attack while diving?

A: Having an attack while underwater will result in serious consequences. Besides difficulty breathing through a regulator (due to the increased work required to breathe underwater), the diver can also develop pulmonary barotrauma during the ascent. Divers know this as a ‘burst lung’ or a ‘pneumothorax’. Air leaks into the blood can also result in a stroke-like condition called cerebral air-gas embolism.

Q: Would diving trigger an attack?

A: The diving environment can predispose divers who suffer from asthma to an attack in the following ways:

  • Physical exertion of diving will be a risk to a person with exercise-induced asthma
  • Breathing in the cold, dry, compressed air from the scuba tanks
  • Diving in cold waters (this may be less of an issue in tropical waters)
  • Salt water is sometimes thought to be a trigger as well

Q: So if I have asthma, can I take up recreational diving?

A: It would depend on how well the asthma is being controlled. Poorly controlled asthma is an absolute contraindication. I would also not recommend diving to someone who has a history of a serious asthma attack, where they’ve had to be intubated and required intensive care.

However, it’s important to note that the diver who appears to have well-controlled asthma (or childhood asthma) should also undergo further evaluation for exercise-induced asthma and bronchial hypersensitivity with a diving physician. You may need to get things such as a chest X-ray, lung function tests, and bronchial challenge tests done as part of the process.

Q: I passed all the medical tests and am able to dive. Now what? Is there anything I can do to look after myself during or between dive trips?

A: If you have been certified to dive after the rigorous investigations and medications – congratulations! But do be aware that you still need to monitor the asthma symptoms. Avoid diving if you have symptoms.

Another way of monitoring your condition is to bring along a Peak Expiratory Flow Rate (PEFR) metre during your dive trip. You can obtain the metre from your local pharmacy or your physician. Test your PEFR twice daily during the dive trip, and if it drops more than 10 percent from your usual PEFR, consider taking a break from diving and get a medical evaluation done.

It is also advisable to return to your diving physician on an annual basis to obtain certification for fitness to dive and to identify any changes to your medical condition.

Dr Greg Chan is a senior specialist physician at The Occupational and Diving Medicine Centre, as well as a visiting consultant at the Hyperbaric and Diving Medicine Centre, Singapore General Hospital. He was previously with the Republic of Singapore Navy, where he trained in Canada and Australia and has written two books for divers: Am I Fit to Dive? and Basic Diving Medicine.