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AQS Code List

AQS Codes and Descriptions

Methods Allowed combinations of parameter + sampling methodology (collection and analysis). This list also includes other information, such as the standard unit, the summary scale and the minimum sample value that is allowed into AQS.
Parameters Not just pollutants but anything that is measurable, including meteorology measurements, i.e., wind speed.
Qualifiers Qualifiers are used when reporting data to AQS. Qualifiers further explain the data.
  • "Null" qualifiers
    • required when submitting a null (i.e., nothing was collected) sample measurement; All Null qualifiers are available for every parameter
  • "QA" qualifiers - optional
    • quality assurance qualifiers are used when data is valid but you want to note something. i.e. measurement was "Below lowest calibration level"
  • "Inform" qualifiers - optional
    • informational qualifiers are used in place of a REQuest EXClusion qualifier; use only when an exclusion of the data will not be requested
  • "ReqExc" qualifiers
    • required when submitting data that is affected by an Exceptional Event and for which an exclusion will be requested
Parameters - Disallowed Qualifiers all List of disallowed qualifiers for each parameter.
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 a 24 hour sample are reportedwith AQS Duration Code = 7.
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 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. 
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.
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. For each monitor, the most recent Certifying agency, PQAO, Collecting Agency, and Reporting Organization is included
Certification Flags A list of all valid Certification Flags
Information on the format of the files:

You can download the full CSV (Comma Separated Values) file from any page that you are on. The CSV files have been designed to import into MS Excel with minimal effort