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TDEC Air Quality Forecasting



Air Quality Forecasts

What is an air quality forecast?

An air quality forecast is much like a weather forecast-it predicts the air quality for the next day. The weather plays an important role in air quality. Hot, dry, stagnant weather allows pollutants to accumulate in an area. For example, ozone pollution is formed when certain air pollutants (oxides of nitrogen and volatile organic compounds) mix and react in hot, sunny weather. When the air is stagnant, pollutants may be suspended in the air over extended periods.

How does the air quality forecast work?

The Tennessee Department of Environment and Conservation (TDEC) issues forecasts in cooperation with the Tennessee Valley Authority and local air quality control programs. Daily air quality forecasts are issued for urban centers of the state, including Tri-Cities, Chattanooga, Knoxville, Nashville and Memphis. Forecasts are reported using the Air Quality Index or AQI, which uses a color-coded system to help you understand quickly if the air quality is expected to be healthy or unhealthy in your community. The U.S. Environmental Protection Agency (EPA) developed this national rating scale based on federal air quality health standards. EPA has assigned a specific color to each AQI category (click to view table).