Fresh Air

I've often wondered when I'm outside how much pollution I am actually inhaling. Just walking down 2 blocks at work in downtown Ottawa and all I can smell is fumes from busses and cigarettes. I've always been very sensitive to smell, and that triggers something inside me to try and get as far away from that smell as possible. I guess it's kind of hard when someone sits next to you on the bus wearing strong cologne/perfume. Even smokers who come on the bus, I can smell it throughout the whole bus. I find it the worst, however, when I am waiting for the bus. I have to stand closer to the street because I am so short that I cannot see the bus numbers any other way, so everytime a bus is stopped to pick up/drop off passengers, I get this strong smell somehow always directed right at me and I feel like I can't breathe. Also, waiting for the bus, there are smokers everywhere and I cannot get away from them. Which makes me wonder, as much as I want to step outside to get away from the circulated, dry air to get "fresh" air, how fresh is it??