I saw another make of these units in the US a few weeks ago in a studio where lots of cigars were being smoked and couldn't believe how fresh the air was a few minutes after the smoking had stopped. I also live fairly close to the airport and the air is filthy. I came back and did quite a bit of research before settling on the Bionaire. When it arrived I sat it in the corner of the room and switched it on and for quite few minutes it revved away while it gave the air a good clean.
My house has two smokers and has always smelled of old smoke but not any more. The big test came when a friend who is an asthmatic and has never smoked came around the following week and I asked him what he could smell. Fresh and clean was the answer.
The unit is a bit noisy when a cigarette is being smoked near it as it detects the smoke and runs faster but when it is in "background mode" it is very quiet.
Two of my sisters have since bought them.