St. Louis, MO-IL
- High ozone days per year: 26
- No. of days with unhealthy particle pollution: 3
- People with asthma: 231,907
- Population: 2,807,216
St. Louis and the surrounding areas have a long history of industrial pollution, mostly due to coal burning for electricity. An ongoing EPA lawsuit initiated over eight years ago alleges that an area power plant has been emitting dangerous levels of sulfur dioxide, in violation of the Clean Air Act.