As the high temperature in D.C. is expected to hit 100°, with a heat index as high as 110°, the Washington Monument is closed ...

An air quality alert has been issued by DC Homeland Security & Emergency Management for the District Saturday. The alert was ...

A hot and humid Thursday will bring a Code Orange Air Quality Alert for parts of the Washington, D.C., area, as temperatures climb into the 90s.

The air quality index is based on concentrations of PM2.5, or fine particulate matter less than 2.5 microns (0.0025 millimeters) in diameter. (For comparison, a human hair is about 20 to 30 times ...

According to the air quality tracking site IQAir, Chicago’s Air Quality Index (AQI) reading of 160 — down from a peak of 166 earlier in the morning — was worse than any major world city ...

Thursday will likely be our first 90+ day of the year. The D.C. area is also under a Code Orange Air Quality Alert.

Tens of millions of Americans sweltered outside or sought air-conditioned refuge as an "extremely dangerous" heat wave ...

Baltimore braces for extreme heat with temperatures potentially breaking records and an Extreme Heat Watch in effect.

Tens of millions of Americans sweltered outside or sought air-conditioned refuge as an "extremely dangerous" heat wave ...

The air quality index, or AQI, measures the air quality and level of health concern it presents as measured by the Environmental Protection Agency. The AQI is measured on a scale of 0 to 500 .