Air Quality Index
Levels of Health Concern
Numerical
Value
Meaning
Good
0-50
Air quality is considered satisfactory, and air pollution poses little or no risk.
Moderate
51-100
Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
Unhealthy for
Sensitive Groups
101-150
Members of sensitive groups may experience health effects. The general public is not likely to be affected.
Unhealthy
151-200
Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.
Very Unhealthy
201-300
Health alert: everyone may experience more serious health effects.
Hazardous
> 300
Health warnings of emergency conditions. The entire population is more likely to be affected.