Hi
@Boston Breakwater ,
People with asthma can be cleared to dive, though criteria varies slightly across practitioners and regions. We will clear a diver with well-controlled asthma as long as he/she has normal lung function with a provocative (dry air) exercise test and doesn't need a rescue inhaler regularly.
Here are the UK guidelines, which are a little more lenient with respect to rescue inhalers but more stringent with respect to monitoring one's own peak flow prior to diving.
A history of spontaneous pneumothorax is typically an absolute contraindication to diving. Recently the diving community has been re-examining this with an eye toward considering those with a single, resolved spontaneous pneumothorax in the distant past for clearance to dive, but most practitioners are understandably still reluctant. If a diver has had a
pleurodesis, it decreases the likelihood of recurrence in that lung significantly and so may work in the prospective diver's favor with respect to recreational diving, but probably not commercial diving.
A diver with a history of traumatic pneumothorax can be cleared to dive provided that radiographic examination (usually a high-resolution CT scan) shows no evidence of scarring or potential for air trapping.
You mentioned the possibility of his pneumothoraces being related to pulmonary overinflation during a dive. That can happen with air trapping on ascent, as you probably know. If we go down that rabbit hole, asthma can cause air trapping, but so can holding the breath during a decrease in ambient pressure.
All that said, if you didn't have any details about this diver's medical history, then I personally think you made a prudent decision. If you have any influence on this gentleman, you may want to consider recommending that he see a diving medical practitioner.
Best regards,
DDM
