jackie seghrari-sabet is here. >> green is good. yellow, orange, be careful. red.hen there's purple. not a human should be outside. >> what is in the air? >> what that what you need to worry about is this chemical reaction between oxygen and pollution. heat puts it all together and you get this thing called ozone, a caustic chemical. >> i see people jogging on the memorial bridge at noon on these nasty days. what's it doing to your lungs? >> it literally burns. >> really? >> people will have worse reactions to that burning. anybody who breathes needs to worry but certainlyasthmatics, young, old. >> hot and nasty one day and we have this rain and it's good the next day and then the heat returning, is it actually clearing out the atmosphere? >> no. remember, we're talking about a chemical reaction. that chemical reaction is burning. where you really see the results of that inflammation is usually prolonged exposure will give you prolonged inflammation. it doesn't get better the next day. in fact, you're not going to see it for two days. >> will you feel it? if you're