16. Chico, CA
Up next in our list of most polluted cities in the US in 2017 is Chico, that is the most populous city in Butte County, California with an estimated population of 225,000. It has a nickname “City of Roses.” It is ranked 25th for high ozone days out of 228 metropolitan areas, then 38th out of 186 metropolitan areas for 24-hour particle pollution, and finally, it is on 68th place for annual particle pollution out of 184 metropolitan areas.
Pixabay/Public Domain
