Baltimore-Columbia-Towson, MD
- High ozone days per year: 39
- No. of days with unhealthy particle pollution: 1
- People with asthma: 263,684
- Population: 2,808,175
Like Salt Lake City, Baltimore is another region prone to thermal inversions, areas where pockets of pollution become trapped under cold air. Because that pollution largely blows in from Midwestern states and settles in the Baltimore region, the state of Maryland sued the EPA in 2017, demanding that the agency apply more regulations to the power plants responsible for the bulk of the air pollution.