Under the Clean Air Act, the U.S. Environmental Protection Agency (EPA) is required to establish a nationally uniform Air Quality Index (AQI) for reporting air quality. The index provides clear and consistent information regarding air quality and associated health risks.
Below are cautionary statements for each AQI category (index value) for ozone and fine particulate matter.
Pollutant-Specific Guidance by Air Quality Index Category
|
GOOD (0-50) |
None | None |
|
MODERATE (51-100) |
Unusually sensitive people should consider reducing prolonged or heavy outdoor exertion | Unusually sensitive people should consider reducing prolonged or heavy exertion. |
|
UNHEALTHY FOR SENSITIVE GROUPS (101-150) |
People with lung disease, such as asthma, children, older adults, and outdoor workers should reduce prolonged or heavy outdoor exertion. | People with heart or lung disease, older adults, children, and people of lower socioeconomic status should reduce prolonged or heavy exertion. |
|
UNHEALTHY (151-200) |
People with lung disease, such as asthma, children, older adults, and outdoor workers should avoid prolonged or heavy outdoor exertion; everyone else should reduce prolonged or heavy outdoor exertion. | People with heart or lung disease, older adults, children, and people of lower socioeconomic status should avoid prolonged or heavy exertion; everyone else should reduce prolonged or heavy exertion. |
|
VERY UNHEALTHY (201-300) |
People with lung disease, such as asthma, children, older adults, and outdoor workers should avoid prolonged or heavy outdoor exertion; everyone else should reduce prolonged or heavy outdoor exertion. | People with heart or lung disease, older adults, children, and people of lower socioeconomic status should avoid prolonged or heavy exertion; everyone else should reduce prolonged or heavy exertion. |
|
HAZARDOUS (301-500) |
Everyone should avoid all outdoor exertion | Everyone should avoid all physical activity outdoors; people with heart or lung disease, older adults, children, and people of lower socioeconomic status should remain indoors and keep activity levels low. |