AIR QUALITY GUIDE
What Do AQI Colors Mean?
A green day, a yellow day, a smoky horizon. The AQI uses colors to make outdoor air information easier to understand.
SIX COLORS, ONE USEFUL START
What the AQI colors mean
The U.S. Air Quality Index groups monitored outdoor pollution into color-coded categories that help communicate possible health concerns. The AQI is a scale from 0 to 500 with no units: the higher the number, the more polluted the air.
Air quality is considered satisfactory; air pollution poses little or no risk.
Air quality is acceptable; there may be a concern for a small number of unusually sensitive people.
Some groups may experience health effects; the general public is less likely to be affected.
Some members of the general public may experience health effects; sensitive groups may experience more serious effects.
Health alert: the risk of health effects increases for everyone.
Health warning of emergency conditions; everyone is more likely to be affected.
BEYOND THE NUMBER
Three details worth checking
Ask which pollutant drives the AQI, when it was measured or forecast, and which reporting area is represented. Air can differ from street to street and indoors.