Having had asthma for most of my life, I believe to be most asthma free after doing exactly the opposite of what my doctors told me. As an asthma patient I was absolutely forbidden from going scuba diving. However, being in love with the sport I took the risk and became a dive master. Diving 2-3 days everyday for 4 months, inhaling 300 - 450 bar daily of compressed air and swallowing some sea water seems to have cleared my asthma as I have had no incidences since and it has been 5 years. It might also be due to other factors but this seemed to be a changing point.