Last
year: #5
Ozone
pollution rank: #24
What's surprising about Pittsburgh's #7 ranking this year is how a city so famous for its pollution from massive steel plants isn't closer to the top of the list like it has been in recent years. Regulations by the Clean Air Act, pollution-reducing renovations to steel plants and a slower economy are all reasons for Pittsburgh's improving air quality. However, U.S. Steel's Clairton Coke Works, the largest steel plant in the nation, is still the biggest source of particle pollution in the city.
