Air Quality System (AQS)

Years Available
1990 to present
Mode of Collection
Surveillance data: active data collection.
The Air Quality System (AQS), formerly the Aerometric Information Retrieval System (AIRS), is the U.S. Environmental Protection Agency's (EPA) repository of ambient air quality data. AQS stores data from over 10,000 monitors, 5,000 of which are currently active. The system contains ambient air pollution data collected by EPA, state, local, and tribal air pollution control agencies. AQS also contains meteorological data, descriptive information about each monitoring station (including its geographic location and its operator), and data quality assurance and quality control information. The Office of Air Quality Planning and Standards (OAQPS) 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. AQS information is also used to prepare reports for Congress as mandated by the Clean Air Act. Air quality data from the AQS system is consolidated at the AirData website. That site has pre-generated files of extracted AQS data at the annual, daily, and hourly level. It also has reports, graphs, and maps that can be generated based on specific selections.
Selected Content
The AQS system contains data on numerous air pollutants measured throughout the country. The Air Quality Index (AQI), a summary measure derived from these data, is an indicator of overall air quality, because it takes into account all of the criteria air pollutants measured within a geographic area.
Population Covered
Air quality measures taken in the 50 states, the District of Columbia, Puerto Rico and the U.S. Virgin Islands.
EPA regulations require state environmental agencies to report air monitoring data at least quarterly. The monitoring agencies must report the measured data, along with metadata about the site, monitoring equipment, and associated quality assurance data to the AQS. Data for a given calendar quarter are due to EPA by the end of the following quarter.
Interpretation Issues
Some values may be absent due to incomplete reporting, and some values may be subsequently changed due to quality assurance activities.