Unlike many places, we don't even have screens on our windows, so the air gets filtered many times by the HVAC units before some of it changes when we come and go. Of course, the house is not actually air-tight.
In our area, most of that kind of 'pollution' is from pollen. We do get 'health advisories' often issued in the extreme heat days during the Summer. In that case, the 'pollution' comes as reely, reeeely tiny infrared particles from the Sun!
BTW, is '
pollen' the root word/cause for creating the word '
pollution' or is that a mere coincidence (or main irritation!)?