You know the difference between the putrid air of the metropolitan area and the searing sting of fresh air out in the country. But which cities are the most toxic? A new study finds out.

At the top of the list is Philadelphia. We knew all that fake cheese from cheesesteaks in the gutters couldn't be good for humanity. Up next is Bakersfield and Fresno, California, because you don't need to be in L.A. to suffer from smog. Number four is our beloved New York—it probably should have been No. 1 just based on subway smells alone—and rounding out the top five is Baton Rouge, Louisiana.

Forbes.com crunched the numbers, ranking the 50 largest metropolitan areas based on the quality of air, water, and the number of toxic Superfund cites in the area. Philly lost because of its high number of Superfund sites, and Fresno and Bakerfield were ranked high because of air pollution. New York, well, it has a little bit of everything, and that's precisely why we love its blackened (cough, cough) heart.

[Image via Getty]