Here's a look at which countries and regions are the most polluted and which are the least, including in the United States. Which US cities are the most polluted? While Ontario, California was the ...

According to IQAir, the most polluted major city in the country last year was Los Angeles. Wildfires in 2024 burned nearly 9 million acres across the United States, roughly equivalent to the size ...

Most cities in the United States had between 5.1 and 15 micrograms of pollution per cubic meter of air, according to IQAir. A number of cities, especially along the West Coast, New England and in ...

Don't let the soft, sepia tones fool you — the United States used to be dangerously ... North Birmingham was the most polluted area of the city. In Cleveland, in 1973, billowing smoke casts ...