11.No. 1: Los Angeles
2021’s smog capital is the Los Angeles-Long Beach metro area, home to 18.7 million people. The city’s crowded freeways definitely play a role in creating ozone levels, but LA’s famous sunny weather doesn’t help. Sunshine ramps up smog levels, aggravating symptoms for the 1.5 million residents who have some form of asthma.
12.Bakersfield, CA, and Year-Round Particle Pollution
This California city once again claims the No. 1 spot when it comes to year-round particle pollution, or soot. High rankings are nothing new for Bakersfield, which led this category from 2016 to 2018. Locals point to oil and gas production facilities, along with its location in the San Joaquin Valley, which traps pollution and holds it in. Wildfires also raised soot levels across the Western U.S.
