The colors are used on air quality forecast maps. No city had a worse sustained reading in 2021 than Salem, Ore., where the index almost reached 500 — the top of the scale — according to ...

A hazardous cloud of toxic air has engulfed a major US city, reportedly causing an emergency alert for toxic chemicals, with ...

Not everyone was reporting the dangerous air quality levels, though. The Environmental Protection Agency’s AirNow is a go-to ...

Good afternoon, Chicago. Readings from several popular weather apps had people across the Chicago area spending much of yesterday wondering whether their air was safe to breathe — until the ...

Man-made air pollution is decreasing, but overall air pollution is worse due in part of wildfire smoke, according to a new ...

AirNow said its air quality index determines the level of air pollution ... The scale goes from 0 to 500, with 500 being the worst.

The National Weather Service has issued an air quality alert for City, Long Island, Westchester and Rockland counties as the ...