This measure, based on data from the Environmental Protection Agency, evaluates states on the number of days the Air Quality Index in counties was not rated “good.” U.S. News calculated a ...

UC Berkeley postdoctoral scholar Samuel Cliff (left) and professor Joshua Apte at the San Francisco Caltrain Station. Each is ...

The United States Environmental Protection Agency monitors and issues air quality standards, which measure the amount of contaminated matter in the air that may be harmful to breathe in. Air quality ...

The United States Environmental Protection Agency monitors and issues air quality standards, which measure the amount of contaminated matter in the air that may be harmful to breathe in.

On November 18 last year, the AQI in Delhi was measured at 999. IQAir, a Swiss company that measures air quality, measured Delhi's AQI on that day at 1600, according to the New York Times.

People living in the national capital New Delhi woke up on Saturday to a thick layer of smog and foggy weather after the Air ...