I avoid cigarette smoke outdoors by moving upwind, moving away, or holding my breath. It's generally much less of an issue in the open air where it disperses quickly.

Other air pollutants can be more of a challenge. I was visiting Denver one winter when their downtown ozone levels were high. That made it a double challenge for my lungs as Denver's elevation is nearly five thousand feet above my home's elevation. We took our grandchildren to the downtown art museum. I don't remember having an asthma attack there, but I felt a moderate, stabbing pain with each inhalation the whole time I was downtown. I think ozone was responsible for that. I endured it and enjoyed visiting the museum with my grandkids.

I rule out visiting places with severe air pollution altogether. I'll never visit Beijing or Fairbanks (in the winter, anyway).

Just yesterday I was finishing my lunch on the mezzanine of an upscale supermarket near my office when a woman drenched in perfume sat at the next table. I'm very sensitive to some perfumes, and hers was one of them. I was hit by an asthma attack after only a few breaths. Luckily I had only a little unfinished soup left. I gathered my trash, stood up, and did something really unusual for me: not sure which of the three women at nearby tables was the perfume-bomb, I spoke up and said "I don't know who's wearing all that perfume, but you should be aware how it affects some people."

Not the most eloquent speech perhaps but it was composed under duress.

I've asked an FA to seat me further from a perfume-drenched fellow pax. I asked her to relay my request to tone down the perfume to the passenger, if she could, but I don't think she did. That particular perfume didn't set me off, as it happened, but it's completely unpredictable so I have to err on the side of caution.