I guess it isn't hard to figure out pollution is bad for you, but it takes a study of half a million to figure out that the public needs to know about it (heh)
LittleBigMan, you have the right idea but the wrong word. Carbonmonoxide (part of the many gasses expelled from automobile exhaust) creats the smog seen over most cities... hmm kidna like Las Vegas
ozone is by defition - A colorless gas (O3) soluble in alkalis and cold water; a strong oxidizing agent; can be produced by electric discharge in oxygen or by the action of ultraviolet radiation on oxygen in the stratosphere (where it acts as a screen for ultraviolet radiation)
it is a highly unstable form of oxygen which is being destroyed by greenhouse gasses and such. anyhow it's not what is bad.
well that's it for the chemistry lesson for today hehe