A long while back, I came across some figures on air quality in different cities... I can't remember if it was around the world or specifically for the USA. Anyways, I have googled for a long while on this subject, and can't seem to get anything decent.
I am interested in how air quality (amounts of pollutants -- NOT natural things like pollen) ranks around the world. I live in Japan, so a study that has lots of Japan-specific info would be really nice.
I just want to compare where I am living now (Toyota) to where I used to live (Detroit) and then figure out where I WANT to live in the future. Air quality is a reasonably important factor as to where I choose to live.
You might poke around here. No idea if Japan has their own version of the EPA (probably do) but that would be the best place to find out. Anyway, on this link you enter a zip code and it has a lot of info on that location. The air quality according to this map is very bad in my area.