The Air Quality Index (AQI) was designed by the EPA to provided a standardized, national method of measuring air quality. It classifies air quality concentrations as good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy and hazardous, based on a scale of 0-500. Each category is color-coded to help make the categories easy to understand.
The U. S. Environmental Protection Agency's color-coded scale for rating air quality1:
|Air Quality Rating||Air Quality Index Number||
|Good||0-50||Green||Air quality is good and poses little to no health risks.|
Air quality is acceptable. It may cause a moderate health concern
|Unhealthy for Sensitive Groups||101-150||Orange||
Members of sensitive groups may experience health effects.
|Unhealthy for General Population||151-200||Red||
Everyone may experience health effects. Sensitive groups may
Health warnings of emergency conditions. The entire populations is
|Hazardous||>300||Maroon||Health alert. Everyone is likely to experience serious health effects.|
1Information from airnow.gov