I recently made plans to take an open-water course with my fiancé, but I have asthma and am worried about whether it is safe for me to dive. I do a great job managing my condition in my daily life, but I know that scuba diving carries its own medical considerations. What should I know before I start scuba diving with asthma?

Asthma
You’re not alone. A huge percentage of the questions we receive at DAN concern scuba diving with asthma. As a chronic lung disease in which the breathing tubes (bronchi) narrow in response to various stimuli — including cold air, exercise and other atmospheric irritants common to divers — asthma understandably poses a risk for people wanting to breathe compressed gas underwater. The primary concern for asthmatic divers is suffering an asthma attack while diving.

Dangers to Divers
All divers experience reductions in breathing capacity due to the effects of immersion and higher gas density in the water. At 33 feet below the surface, for example, the maximum breathing capacity for a healthy diver is only 70 percent of what it is at the surface; at 100 feet, breathing capacity drops to approximately 50 percent. Having asthma further decreases the amount of air you can move through your lungs. Therefore, divers with asthma may not be able to accommodate the increased breathing requirements demanded by exertion.

It is also possible for gas to become trapped in the lungs during ascent, which can result in lung rupture and cause arterial gas embolism (AGE) or pneumothorax (collapsed lung). Still, divers with well-controlled and properly treated asthma are not necessarily at increased risk for AGE.

You should also be aware that factors underwater can trigger or worsen attacks (exercise, cold air, sea water, etc.), and it can be difficult or impossible to stop exercise to catch your breath during a dive — similar to how it feels during a cold, early-morning run.

Recommendations
Historically, diving medicine physicians advised against any diving with asthma. However, in 1995, the Undersea Hyperbaric Medical Society (UHMS) proposed more liberal guidelines in which the risk of diving could be considered acceptable for certain divers under certain conditions. Two key qualifications for diving candidates with asthma include ensuring that the asthma is of a mild nature and that treatment is working well enough to prevent an acute attack while underwater or on the surface. Following that, it is crucial that anyone with asthma consults with a doctor trained in diving medicine prior to diving.

Precautions
Every individual and every case is different. When you find a doctor trained in dive medicine, you will need to work together to tailor your asthma action plan to the demands of diving. Certain anti-inflammatories, bronchodilators and other beta-agonists may relax your bronchial muscles, reduce swelling and mucus production and open up airways enough for you to dive with relative safety. People whose asthma is well controlled may lead normal lives that include exercise, and they are less likely to experience an asthma attack while diving.

Additional Considerations
You mentioned that you will be learning to dive with your fiancé, who should be trained to recognize and respond to an attack. You must also notify your divemaster and your group about your condition and explain what to do in case of emergency. Lastly, you need to prepare yourself for the possibility that you may need to call off a dive if you are having any problems. By the time you get in the water, you should be able to assure your fellow divers that they can breathe easy knowing you’ve taken the proper precautions.

For more dive-training and safety recommendations and tips, visit the Training, Safety and Health section of our website.

For more information, visit DAN.org/Health.