| 0-50 |
Good |
Air quality is considered satisfactory, and air pollution poses little or no risk. |
| 51-100 |
Moderate |
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. |
| 101-150 |
Unhealthy for Sensitive Groups |
Members of sensitive groups may experience health effects. The general public is not likely to be affected. |
| 151-200 |
Unhealthy |
Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects. |
| 201-300 |
Very Unhealthy |
Health warnings of emergency conditions. The entire population is more likely to be affected. |
| 300+ |
Hazardous |
Health alert: everyone may experience more serious health effects. |
