Move out of the city?
Years ago when I was working in Bangkok I was amazed at how all the traffic cops wore those gas masks and I thought all the people smoking cigarettes were probably better off than anyone just breathing the air... at least the cigarettes had filters...
Going over the 59th Street Bridge is where I get my daily commuting hill climb, it's also the place where I notice the fumes the most. I just try and keep it easy enough and keep my breathing easier and through my natural nasal filtering system... or perhaps I should augment that with some cigarette filters shoved up my nose...