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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.

Parameters/Methods/Units/Durations General Geographic
[?]Valid Combinations - All Parameters [?]Qualifiers - all [?]Agencies - all
Met only spacer[?] QA only spacerTribal only
Criteria only spacer[?] Null only  
HAPS only spacer[?] Inform only [?] States & Counties
Core HAPS only spacer[?] ReqExc only [?] Cities
PAMS only   [?] CBSAs
PAMS VOC only [?]Parameters +  All Qualifiers [?] CSAs
Improve Carbon only spacerParameters + QA only  
Improve Speciation only spacerParameters + Null only [?] Legacy MSAs
PM10 Speciation only spacerParameters + Inform only [?] Legacy CMSAs
PM10-2.5 only spacerParameters + ReqExc only  
PM2.5 Continuous nonreference only spacerParameters  
PM2.5 Mass and QA only    
Speciation only [?] Units  
Speciation cation/anion only [?] Durations  
Speciation carbon only    
Speciation metals only [?] Collection Frequencies  
[?]UATMP Carbonyl only [?] Monitor Types  
UATMP VOC only [?] Pollutant Standard IDs  
  [?] AQI breakpoints  
  [?] Legacy Null data codes  


Parameters - Allowed combinations of parameter + sampling methodology (collection and analysis) + reported unit + duration (sometimes called "Protocols").   If you do not see the combination here, it is not allowed into AQS. If you believe that we are missing a valid combination, please contact the AQSTeam. 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 are not just pollutants but anything that is measurable, including meteorology measurements, i.e., wind speed. To make the files smaller, we also broke out selected groups of parameters and show the valid combinations for just those.

UATMP - Urban Air Toxics Monitoring Program

Qualifiers all - Qualifiers are used when reporting data to AQS. Qualifiers further explain the data

Parameters + Qualifiers all - List of parameters and the qualifiers that are open for each. ** Null open for all parameters.  QA, Informand 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 Standards - 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 AQSTeam to have your state added to the list of states that can use that agency code.

State and County - 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

MSAs - Metropolitan Statistical Areas (MSAs) - here for informational purposes only. MSAs were replaced by CBSAs.

CMSAs - Combined Metropolitan Statistical Areas (CMSAs) - here for information 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

Information on the format of the files:

AQS Frequent Questions | Technology Transfer Network | Air & Radiation

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