5. California: Clean Air
California is ranked as one of the most polluted states in the U.S., which is surprising when you consider the state's beautiful coastlines and majestic national parks. But thanks to major metropolitan cities like Los Angeles, Fresno, and Sacramento, the state has an issue with its air quality. It's repeatedly ranked as the state with the most air pollution, but that's not only because of car emissions. It's also because of wildfires.

According to Sacramento Bee in 2020, "The researchers say climate change is responsible for more intense wildfires that produce dangerous smoke, contributing to poor air quality across western communities."