Ozone is deadly for a lot of people with asthma or COPD. It's a common urban pollutant (produced from car fumes). Interesting study here:

http://www.eenews.net/stories/1060023092

(i.e. yet another way America has been deliberately turned into a death camp for black people, with, as usual, the Koch brothers as its chief gauleiters).

EPA says reducing ozone pollution to between 65 and 70 ppb would prevent between 750 and 4,300 premature deaths, between 1,400 and 4,300 asthma-related emergency room visits, and between 320,000 and 960,000 asthma attacks in children yearly by 2025.