| 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. |
