The AQI focuses on what you might experience if exposed within a few hours or days after breathing polluted air.
The Environmental Protection Agency calculates the AQI using 5 major air pollutants regulated by the Clean Air Act:
- Ground-level ozone
- Particle pollution (also known as particle matter)
- Carbon monoxide
- Sulfur Dioxide
- Nitrogen Dioxide
AQI BY THE NUMBERS
The AQI runs from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern.
The index is divided into six categories, each corresponding to a different level of health concern.
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An AQI of over 100 triggers an alert for vulnerable groups.
Levels over 300 signal a health emergency and everyone is more likely to be affected.
Full breakdown:
Green - Good: 0 to 50. Air quality is satisfactory, and air pollution poses little or no risk.
Yellow - Moderate: 51 to 100. Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
Orange - Sensitive Groups: 101 to 150. Members of sensitive groups may experience health effects. The general public is less likely to be affected.
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Red - Unhealthy: 151 to 200. Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.
Purple - Very Unhealthy: 201 to 300. Health alert: The risk of health effects is increased for everyone.
Maroon - Hazardous: 301+. Health warning of emergency conditions: everyone is more likely to be affected.
Learn more about the index from the EPA at AirNow.gov.
6abc Air Quality Tracker