About AQS

The Air Quality System (AQS) is a computer-based information management system for handling the storage and retrieval of information pertaining to ambient outdoor airborne pollutants, other substances, and related meteorological data. The AQS database uses Oracle database software and access to the database is provided via web browser. AQS is administered by the U.S. Environmental Protection Agency (USEPA), Office of Air Quality Planning and Standards (OAQPS) in Research Triangle Park, North Carolina.

The collection and maintenance of air quality data is required to establish and enforce the standards set by the following Federal Acts and Amendments:

  • 1955: Air Pollution Control Act - “An Act to provide research and technical assistance relating to air pollution control” Reserved for Congress the right to control pollution.

  • 1963: Clean Air Act - Emissions standards for stationary sources and compliance deadlines for States

  • 1965: Motor Vehicle Air Pollution Control Act - Emissions standards for vehicles

  • 1967: Air Quality Act - Created Air Quality Control Regions (AQCR) and timetables for State Implementation Plans (SIP)

  • 1970: Amendments to the Clean Air Act - National Ambient Air Quality Standards (NAAQS), New Source Performance Standards(NSPS), New motor vehicle standards, and compliance timetable

  • 1990: Amendments to the Clean Air Act - Modification of standards and timetables

The monitoring data in AQS are the result of the various Clean Air Act requirements to provide a national database of ambient air pollution data: Criteria pollutant (SO2, NO2, O3, CO, PM10, PM2.5 and Pb) data, air toxic data, photochemical assessment data, and meteorological data. Individual observations, as well as summarized data are provided. The database contains values from 1957 through the present day. AQS contains hundreds of millions of observations, coming from tens of thousands of monitors.

As regulations broaden to include more pollutants, the AQS system expands. For hazardous air pollutants (HAPS) the USEPA is currently gathering data and has proposed baselines for limiting emissions. There are currently over 1500 substances that AQS is prepared to track and additions are made as needed.

In addition to the ambient pollutant concentration data, AQS contains descriptive information about the location of the monitoring site (e.g., address, latitude/longitude, local site name, etc.) where the ambient data are collected as well as information about the types of monitors used to collect the ambient measurements. Quality assurance information is also contained in the AQS.

The air pollution monitoring data residing in the AQS database is submitted directly to the database by many different groups. The State, Tribal and Local air pollution agencies throughout the United States routinely submit monitoring data from the air monitors that they manage. Some Federal agencies, including USEPA and private companies also supply data directly. The data submitted by these various groups are “owned” by those groups. In other words only the agency responsible for a monitor at a site can maintain that monitor’s data. USEPA will only change data as a last resort. USEPA’s OAQPS maintains the administrative data in AQS (e.g. reference tables and codes, security tables, and overall software maintenance).

AQS data are not real time, because observation data are quality assured by the submitting agencies before loading into the database. Agencies generally have 3 months to collect, analyse, compute, and quality assure the values prior to loading the data into AQS. Each year, the monitoring agencies certify to USEPA that the criteria pollutant data values for that year are correctly stored in the database. This data serves as the basis for area designations (e.g. non-attainment designations), among many other uses. In addition to providing data for evaluating conformance to Federal regulations, data from the AQS is used to fulfil air quality information requests from the public.

Air quality data is available on AQS from 1957 onward. Only State, Local, Tribal, and Federal air pollution control agency staff are allowed to access AQS directly. See the AirData website for details on how anyone access the data from outside of AQS.