MSD Manual

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Air Quality Index*

Air Quality Index*

AQI Values

Level of Health Concern (Air Quality Condition)

0–50

Good

51–100

Moderate

101–150

Unhealthy for members of sensitive groups†

151–200

Unhealthy

201–300

Very unhealthy

301–500

Hazardous

* The AQI is based on the levels of 5 pollutants regulated by the U.S. Environmental Protection Agency under the Clean Air Act. The pollutants are ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide.

† Members of sensitive groups include people with lung or heart disease, children, and older adults.

AQI = air quality index.

Adapted from US Environmental Protection Agency: Air quality index: A guide to air quality and your health. Research Triangle Park, NC, 2009.