Understanding the Air Quality Index and How it Affects You

Map from shows today’s air quality for the country.

Each day, the Environmental Protection Agency measures 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. Based on these measurements, air quality around the country is graded on a scale from 0-500 called the Air Quality Index (AQI). The lower the AQI number, the safer the air is to breathe. As the number gets higher, breathing the air could lead to health problems, especially if you have asthma or other respiratory illness.

The above map shows today’s air quality forecast based on AQI values across the country.

Find the daily air quality for where you live and learn more about precautions you can take if the air quality is poor.

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