Unhealthy PM2.5 exposure in the U.S.

An estimated 63.7 million Americans are living in places with failing grades (F) for unhealthy daily levels of particle pollution (PM2.5). Nearly 20 million Americans live in counties where year-round particle pollution levels are worse than the national air quality limit, and that receive a failing grade. People who live in areas with high exposure to PM2.5 are at risk of harm to their health.

Number of Americans at risk of unhealthy levels of particle pollution in the United States between 2019 and 2021 (in millions)

Characteristic	A	B	C	D	F	Pass	Fail
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-

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Release date

April 2023

More information

Region

United States

Survey time period

2019 to 2021

Special properties

Data from 922 counties

Supplementary notes

The majority of U.S. counties don’t have monitors — which means that many communities, especially rural ones, don’t have official monitored information on their air quality. Please note that the population figures in this statistic are only for those places that collect air pollution data, and do not reflect the entire population of these groups in the U.S. PM2.5 concentration information is for the three-year period for 2019-2021 for each monitoring site.

Grades are assigned based on the weighted averages as follows: A=0.0, B=0.3-0.9, C=1.0-2.0, D=2.1-3.2, F=3.3+. The concentration of a pollutant is based on the National Ambient Air Quality Standard for PM2.5, which is 12 µg/m3. Counties with design values of 12 or lower received a grade of “Pass” for Annual PM2.5. Counties with design values of 12.1 or higher received a grade of “Fail.”

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