The EPA's Air Quality Index can tell you whether breathing outside air can be harmful. Here's how to read the scale to plan ...

Milwaukee, Ozaukee, Racine, Kenosha and Sheboygan are all under a poor air quality alert from noon to 11 p.m., according to ...

The building heat and humidity comes as Chicago's air quality readings early Monday morning were "unhealthy for sensitive groups," the website AirNow.gov said. The air quality ranked as a level three ...

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.” ...

The Air Quality Index (AQI) is used by various government agencies to report how clean or polluted the air is in your area. For example, you may have spotted this metric popping up in local ...