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The AQI is an index for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. The AQI focuses on health effects you may experience within a few hours or days after breathing polluted air. EPA calculates the AQI for five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide. For each of these pollutants, EPA has established national air quality standards to protect public health.
Index Values |
Levels of Health Concern |
Cautionary Statements |
---|---|---|
0 to 50 - Green |
None |
|
51 to 100 - Yellow |
Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. |
|
101 to 150 - Orange |
Active children and adults, and people with lung disease, such as asthma, should reduce prolonged or heavy exertion outdoors. |
|
151 to 200 - Red |
Active children and adults, and people with lung disease, such as asthma, should avoid prolonged or heavy exertion outdoors. Everyone else, especially children, should reduce prolonged or heavy exertion outdoors. |
|
201 to 300 - Purple |
Active children and adults, and people with lung disease, such as asthma, should avoid all outdoor exertion. Everyone else, especially children, should avoid prolonged or heavy exertion outdoors. |
|
301 to 500 - Maroon |
Everyone should avoid all physical activity outdoors. |
The EPA’s AIRNOW web site contains general information about air pollution plus real-time and forecast air quality data. It also contains facts about the health and environmental effects of air pollution, steps you can take to protect your health and to reduce pollution, and links to state and local air pollution agency web sites.