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AQS Codes and Descriptions
Links go to HTML pages that are refreshed nightly. The pages can be downloaded as comma separated values (CSV) files. File format information here.
Click on the 
for more information on each topic.
| Valid Combinations of Parameters and Methods |
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| Parameters | not just pollutants but anything that is measurable, including meteorology measurements, i.e., wind speed. | |
| UATMP | Urban Air Toxics Monitoring Program. | |
| Qualifiers all |
Qualifiers are used when reporting data to AQS. Qualifiers further explain the
data.
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| Parameters + Qualifiers all | List of parameters and the qualifiers that are open for each. ** Null open for all parameters. QA, Inform and ReqExc open for some parameters. | |
| Collection frequencies | the amount of time between sample observations. | |
| Durations | required when reporting a measurement; the length of time used to acquire a sample measurement (can sometimes called the interval) E.g., measurements for ozone monitors that run continuously are reported as hourly average concentrations with AQS Duration Code = 1. | |
| Units | Units of measurement. Apply to both Reported and Standard Sample Values. | |
| Monitor types | Indicates the purpose of a monitor. Each monitor is required to have at least one monitor type. | |
| Pollutant Standard IDs | Every NAAQS has a unique Pollutant Standard in AQS, i.e. "2008 8-hour ozone NAAQS". | |
| AQI breakpoints | For select pollutants, the AQI transforms ambient concentrations to a scale from 0 to 500. Since AQS generates the AQI values, we also store the breakpoints for the AQI ranges ("Good", "Moderate", "Unhealthy" for sensitive groups" or "Unhealthy", "Very unhealthy", "Hazardous".). | |
| Agencies | Air pollution control agencies and other organizations reporting data to AQS. If an agency you need already exists, but is not shown for your state within AQS, contact the EPA Call Center to have your state added to the list of states that can use that agency code. | |
| State and Counties | FIPS codes for all the states and the counties contained therein. | |
| Cities | FIPS codes for cities. | |
| CBSAs | Core-Based Statistical Areas (CBSAs) - defined by OMB in June 2003; areas based around an urban center of > 10,000 people and adjacent areas; designations are made using US Census numbers. | |
| CSAs | Combined Statistical Areas (CSAs) - defined by OMB in June 2003; areas based on adjacent CBSAs; designations are made using US Census numbers. | |
| Legacy MSAs | Metropolitan Statistical Areas (MSAs) *** Informational purposes only. MSAs were replaced by CBSAs. | |
| Legacy CMSAs | Combined Metropolitan Statistical Areas (CMSAs) *** Informational purposes only. CMSAs were replaced by CSAs. | |
| Legacy Null data codes | Mapping of the old mainframe codes to the newer Null qualifier codes. *** Informational purposes only. | |
| Quality Assurance Project Plans (QAPPS) | Contains a list of all agencies that have submitted QAPPs and approval dates by EPA Region where appropriate | |
| Certifying Ageincies by Monitor | A list of criteria monitors that were active during 2012. For each monitor, the most recent Certifying agency, PQAO, Collecting Agency, and Reporting Organization is included | |
| National Performance Audit Program (NPAP) data | Independent site audits as required by the Monitoring Plan or Quality Assurance Program Plan (QAPP) for gaseous criteria monitors. These audits are usually performed by USEPA and reported to AQS as NPAP audits. | |
| Certification Flags | A list of all valid Certification Flags | |
| Information on the format of the files: |
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