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 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 ...

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.” ...