If it's there, I can smell it.

I can smell a burning cigarette 3 rows away in a parking lot. Living in Arizona, there's lots of dust and I'm constantly trying to get rid of it in my house. We have a "scrubber" (not as large as in a hospital, but the same thing). I can walk from room to room in my small home and smell the dust in the room I haven't dusted much. I used to appraise houses, which were usually repos. If there was mold, I'd be sick in a couple of days. Even though I have sinus issues, asthma, and bronchitis flares, I can still pick up scents of things that affect my breathing. I used to live along the border of a state forest in Michigan - I used to get both viral and bacterial lung infections - at the same time.