1 Air Quality System (AQS)

1.1 Organization

US Environmental Protection Agency (EPA)

1.2 Website

https://aqs.epa.gov/aqsweb/documents/data_mart_welcome.html

1.3 Description

AQS Data Mart contains all information from AQS
Collects data as part of the national ambient air monitoring program
- Air pollution data from over thousands of monitors
- Meteorological data, descriptive information about each monitoring station, data quality assurance and quality control information
The most commonly requested aggregation levels of data (and key metrics) are:
- Sample values as standard units (e.g. 1-hour or 24-hour averages)
- NAAQS average values (8-hour for ozone and CO, 24-hour for PM2.5)
- Daily summary values (e.g. observation count, percent, mean, max and time of max, air quality index, number of observations greater than standard)
- Annual summary values (e.g. observation count and percent, valid days, required/null/exceptional observation counts, mean and standard deviation, maximum observations, percentiles, number of observations greater than standard)
- Site and monitor information (FIPS state code, FIPS county code, site number, parameter code, parameter occurrence code, latitude, longitude, measurement method information, owner/operator/data submitter, monitoring network, exemptions from regulatory requirements, operational dates, city and CBSA
- Quality assurance information (for 19 possible QA assessments)

1.4 Vintage/Release Frequency

Database started in 1957, but national consistency begins in 1980. There are weekly updates, however, data is not real time and usually within 6-9 months of collection.

1.5 Observational Unit

Varies (measurements, averages, summaries, etc.)

1.6 Collection Methodology

Data submitted by tribal, state, and local agencies
Data subjected to several quality control tests

1.7 Available at

Pre-generated data files containing 1.5 billion rows of data updated twice a year are available at https://aqs.epa.gov/aqsweb/airdata/download_files.html
Aggregated or visual data from AQS or large files of pre-extracted data available at https://www.epa.gov/outdoor-air-quality-data
Row-level data from the AQS database is available with sign up. Single queries must be limited 20 2 million rows. https://aqs.epa.gov/aqsweb/documents/data_api.html.

1.8 User Guide/Data Dictionary

https://www.epa.gov/aqs/aqs-manuals-and-guides

1.9 Cost

Free

1.10 Proposal or Application required?

1.11 DUA required?

1.12 Special Notes

No restrictions on data use
Suggested citation: US Environmental Protection Agency. Air quality System Data Mart [internet database] available at http://www.epa.gov/ttn/airs/aqsdatamart. Accessed Month DD, YYYY