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 ...

The DEC has issued an air quality health advisory for most of upstate New York due to elevated levels of fine particulate ...

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

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.” ...