As of Wednesday, more than 400 wildfires were burning across Canada, leading to air quality alerts − indicators the air is unsafe to breathe for certain people − across much of the eastern U.S.

Unhealthy Air Quality Index level. Red: Indexes in the 151 to 200 range are considered "unhealthy." At this level, any member of the general public becomes susceptible to health effects.

Canadian wildfire smoke returns, bringing haze to Michigan. As of July 25, advisories are in effect for the U.P. and northern ...

Thursday: A slight chance of showers and thunderstorms after 2 p.m. Sunny, with a high near 94. Heat index values as high as ...

An air quality alert was issued by the National Weather Service in Milwaukee-Sullivan at 1:52 p.m. on Wednesday, July 23.

The EPA's AQI ranges from 0 to 500 and represents the measurement of these five different major pollutants regulated by the Clean Air Act.

A combination of high heat, poor air quality, and the threat of severe thunderstorms is bearing down on New York City this ...

MIchigan's air quality will be unhealthy for some groups Friday. Check the air quality index map to see if it's good or bad ...

As of Tuesday morning, the Air Quality Index in Milwaukee was between 115 to 120, which falls in the "unhealthy for sensitive ...

An air quality alert will be in effect across all of Minnesota until at least 11 p.m. July 25, according to the state ...

Heat advisory and air quality alert has been issued for the Lower Hudson Valley July 25 as heat index levels are predicted to ...

AirNow and PurpleAir use the Air Quality Index, or A.Q.I., a measure of air quality from 0 to 500 that is composed of six categories, from “good” to “hazardous.” ...