| 0 – 50 |
Good |
0.0 – 12.0 |
Air quality is satisfactory; poses little or no health risk. |
| 51 – 100 |
Moderate |
12.1 – 35.4 |
Acceptable air quality. Unusually sensitive people may have mild symptoms. |
| 101 – 150 |
Unhealthy (Sensitive) |
35.5 – 55.4 |
Sensitive groups (asthma, elderly) may experience health effects. |
| 151 – 200 |
Unhealthy |
55.5 – 150.4 |
Everyone may begin to experience adverse health effects. |
| 201 – 300 |
Very Unhealthy |
150.5 – 250.4 |
Health alert: risk of health effects for the entire population. |
| 301+ |
Hazardous |
250.5+ |
Emergency conditions. Everyone is likely to be affected. |