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Key Indicators for Understanding Our Region

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Sustainability / Air Quality

Small particles (“particulate matter”) less than 2.5 micrometers in diameter are referred to as PM2.5. These particles are so small that they can get deep into the lungs and cause breathing problems. PM2.5 is caused by all types of combustion, including motor vehicles, power plants, residential wood burning, forest fires, agricultural burning, and some industrial processes. PM2.5 is carried by the wind, so particulate matter generated in one state can affect PM2.5 levels in downwind areas.

The U.S. Environmental Protection Agency has established standards requiring that the maximum daily PM2.5 level at any location be no greater than 65 micrograms per cubic meter, and the annual average of the daily PM2.5 maximums at any location be no greater than 15 micrograms per cubic meter.

The Ozone reporting season lasts from April to October.

Current Air Quality - Western Pennsylvania


This map from the EPA AirNow website shows the hourly PM2.5 levels at the subset of monitoring locations that report continously on a daily basis. The colors show PM2.5 levels based on the EPA's Air Quality Index. Green means ‘Good’, Yellow means ‘Moderate’, Orange means ‘Unhealthy for Sensitive Groups’ and Red means ‘Unhealthy’. For more information, visit the EPA's AIRNow website.