Hazardous is 301 to 500. The entire population is more likely to experience serious health effects and should avoid all outdoor exertion.

Very Unhealthy is 201 to 300. Everyone may experience more serious health effects and should avoid all outdoor exertion.

Unhealthy is 151 to 200. Everyone may begin to experience some adverse health effects and should limit prolonged outdoor exertion. Members of the sensitive groups should avoid prolonged outdoor exertion.

Unhealthy for Sensitive Groups is 101 to 150. People with heart and lung disease, older adults and children are at a greater risk and should limit prolonged outdoor exertion.

Moderate is 51 to 100. People who have a unique sensitivity to air pollution should consider limiting prolonged outdoor exertion.

Good is 0 to 50. No health impacts are expected when air quality is in this range.