The Air Quality System (AQS) contains ambient air pollution data collected by EPA, state, local, and tribal air pollution control agencies from thousands of monitors, along with meteorological data, descriptive information about each monitoring station including geographic location and operator, and data quality assurance/quality control information. AQS stores data from over 10,000 monitors, 5,000 of which are currently active, and contains measurements of criteria air pollutants and hazardous air pollutants throughout the country.
The AQS Data Mart contains approximately 3.4 billion rows of data including measurements, National Ambient Air Quality Standards (NAAQS) averages, daily and annual summaries, site and monitor descriptions, and quality assurance results. EPA regulations require state environmental agencies to report air monitoring data at least quarterly, with data for a given calendar quarter due by the end of the following quarter, and a key milestone of May 1st by which all data for the prior year should be complete. Data is available back to 1990 with files summarized on annual, daily, and hourly bases.
The Office of Air Quality Planning and Standards and other AQS users rely on the system data to assess air quality, assist in Attainment and Non-Attainment designations, evaluate State Implementation Plans for Non-Attainment Areas, perform modeling for permit review analysis, and other air quality management functions. Researchers, public health officials, environmental agencies, and the public use AQS data to track pollution trends, identify areas exceeding air quality standards, study health impacts of air pollution, support epidemiological research, and inform regulatory decisions aimed at protecting public health and the environment across the United States, Puerto Rico, and the U.S. Virgin Islands.