According to the ranking in IQAir's 2024 World Air Quality Report, these are the 10 U.S. cities with the worst pollution in North America: While eight of the most polluted U.S. cities in North America were in California, with the remaining two in Texas, the two least polluted regional cities were both located in Hawaii: Waimea and Ocean View.

Chad, in central Africa, is the world’s most polluted country, while California has the worst air pollution in North America, according to an IQAir report.