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Basic Information

The Air Quality System (AQS) contains ambient air pollution data collected by EPA, state, local, and tribal air pollution control agencies from thousands of monitoring stations.  AQS also contains meteorological data, descriptive information about each monitoring station (including its geographic location and its operator), and data quality assurance/quality control information.  The Office of Air Quality Planning and Standards (OAQPS) and other AQS users rely upon the system data to assess air quality, assist in Attainment/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.

Today, States, Local and Tribal agencies submit their data directly to AQS via this web application.  Registered users may also retrieve data through the AQS application and through the use of third party software such as the Discoverer tool from Oracle Corporation.  Data from AQS is also available via the AQS Data Mart.

User Support is provided through the EPA Call Center. The toll free number is 866-411-4EPA Select 9.

Timeliness and Accuracy of Data

EPA regulations require state environmental agencies to report air monitoring data at least quarterly. Data for one calendar quarter are due to EPA by the end of the following quarter. However, some values may be absent due to incomplete reporting, and some values may be subsequently changed due to quality assurance activities.

If you find an error in AQS, we hope you will let us know so that we may correct it. You may use the Contact Us link or you may contact directly the people responsible for the data.  Air monitoring: state environmental agencies

AQS Frequent Questions | Technology Transfer Network | Air & Radiation

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