About the Air Quality Levels

AQI

Air Pollution Level

Health Implications

Cautionary Statement (for PM2.5)

0 to 50

Good

Air quality is considered satisfactory, and air pollution poses little or no risk

None

51 to 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.

Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.

101 to 150

Unhealthy for Sensitive Groups

Members of sensitive groups may experience health effects. The general public is not likely to be affected.

Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.

151 to 200

Unhealthy

Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects

Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion

201 to 300

Very Unhealthy

Health warnings of emergency conditions. The entire population is more likely to be affected.

Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.

300+

Hazardous

Health alert: everyone may experience more serious health effects

Everyone should avoid all outdoor exertion

Five major pollutants

EPA establishes an AQI for five major air pollutants regulated by the Clean Air Act. Each of these pollutants has a national air quality standard set by EPA to protect public health: