Hi, My friend had a spontaneous pneumothorax about 3 years back. It was a mild one. The doctor said he will be ok after sometime. There was no pain after about 2 years. He is a smoker. Is there a chance he might get again.  Also he was advised not to fly for a while. Can he take airtravel now. It has been about 3 years since this happened

Summarized question: What are the changes of a relapse of spontaneous pneumothorax?