I don't disagree with you on this....but if you put down on a pre-dive/pre-dive instruction medical questionnaire that you have a history of asthma, it is unlikely the instructor or operation is going to take your word for it that you are a low enough risk for them to take you in the water without a signature from competent medical authority. I experienced this myself as I put on my paperwork back in 1995 that I had exercise induced asthma as a child. I took my OW class as a university course that included NAUI certification. Two days before the open water checkout dives, my instructor pulled me aside and mentioned that he let me participate in the course in the pool but was not comfortable with taking me in open water due to my history of asthma. He said he would do it if I had a statement signed by a DAN affiliated doctor....unfortunately at the time there were no DAN affiliated docs that were apart of my parents HMO. Once I graduated and had my own medical insurance I found a DAN affiliated doc that accepted my insurance and he evaluated me and signed that I was ok to dive despite the previous history of asthma. Unfortunately my instructor was down in the Caribbean for the spring/summer and since I had graduated there was little to no chance that I would ever meet up with him again without significant effort on my part. I still dove in the interim, but without a c-card it was always a huge pain in the arse to rent equipment and get gas fills. Fast forward to 1998 and I was stationed at a medical clinic in Mountain View California as a Hospital Corpsman (Navy medic)...I had taken care of an older gentleman who gave me his business card, mentioned he was a retired Marine Corps Sergeant Major and had lived through multiple combat tours in Vietnam, specifically due to the efforts of the Hospital Corpsmen assigned to the units he was a member of (the Marines don't have their own medics or doctors, they rely on the Navy for this). He said if there was anything he could do for me to just ask. I looked down at his business card and noticed he was the owner of the dive shop down the road from the base. I told him my story and he invited me to his shop to meet one of his instructors who was wrapping up an OW class and was going to be doing the checkout dives in Monterey Bay that weekend. The instructor gave me the written exam, which I had no problems passing, and then invited me to do the checkout dives with his class. I received my OW cert card a couple of weeks later in the mail from SSI.
All this to say that I am very familiar with Asthma, as I grew up playing sports and carrying both a ventolin and intal inhalers. With a background in Athletic Training (sports therapy), trained EMT, and background as a Hospital Corpsman with a specialty as an aerospace med tech, I understand the physiological mechanism and response, as well as the triggers of asthma fairly well. I also understand that, like me and you, there are plenty of people out there who have a history of asthma and dive. I can fully appreciate your assessment that you are low risk, and would not disagree with you...but that being said, there is nothing untrue about my sentiment that if you have recently been symptomatic due to certain precursors that you might go your whole life without having an episode without those specific precursors being present or you may have one unexpectedly without those specific precursors being present. For instance the typical precursor for you is dust...but a high index of pollen can spur an attack as it can have an affect similar to dust but in smaller quantities in the air due to an autoimmune stimulating effect it can cause. Your doctor obviously was comfortable signing off that the risk of an asthmatic episode while diving was unlikely...again I don't disagree, but the reality is that if you have a recent history of being symptomatic it is a risk...the risk may be calculated, but its still a risk.
-Z
