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 EPA's air-quality index (AQI) measures how safe, unhealthy, or hazardous the air is outside. Here's a guide on how to read AQI.

AirNow.gov Air Quality Index (AQI) Basics for Ozone and Particle Pollution. airnow.gov Ways To Protect Yourself When AQI Is Above 150. Even small amounts of exposure to poor air can be harmful to ...

The AQI complication on an Apple Watch measures the Air Quality Index in your area. Here's how the EPA calculates it, and how to use it on your watch.