This map shows predictions of ground level hourly Ozone (O3) concentrations for the continental US, based on a photochemical model. This is a joint NOAA-EPA product of the Air Quality Forecast System by the National Weather Service. This guidance product is for state and local air quality forecasters, but does not constitute an official air quality warning or alert from the National Weather Service. Please refer to your official current air quality forecast which is available at the EPA AIRNow web site.