Download Detailed AQS Data

¹ parmcodesbyclasscode.xls (9/27/07, 84K) Look in spreadsheet for "Volatile Organic Compound subset of the PAMS Parameters"

² parmcodesbyclasscode.xls (9/27/07, 84K) Look in spreadsheet for "PM2.5 Speciation"

³ Current speciation data files contain the "raw" speciation data from the national PM2.5 network. The organic carbon data are reported as measured and have not been blank-corrected. The EPA is currently exploring options for correcting carbon data.  Guidance will be posted when available.  Please review the attached technical note from Phil Lorang.

⁴ "RD_501_88101_LC_Daily_yyyy.ZIP" - These data files on the AQS web site contain the data collected by EPA approved reference and equivalent methods for sampling for PM2.5. This is the highest quality data . These samples are collected for 24-hrs from midnight to midnight local standard time either every day, every 3rd day or every 6th day. This is the data that is used by EPA to determine whether an area is in attainment or nonattainment of the National Ambient Air Quality standards.   Hourly PM2.5 samples are no longer provided here, though they are available upon request. These data have more uncertainty associated with them which the user should be aware of. For example, these data are not collected with approved referenced or equivalent methods so the data should not be compared with the standards for attainment determinations or other regulatory purposes. These samplers are more variable in the data quality with the dependency including more variation dependent on the particulate composition. Also, some of this data has been corrected for sampler variation by the submitting agencies while other data submitted by other agencies has not been.  (The sampling method code can provide some insight into what correction has been applied.) The continuous PM2.5 samplers report hourly averages which must be summarized to compute a midnight to midnight average.

⁵ "RD_501_SPEC_yyyy.ZIP" - These files contain the PM2.5 data concentrations as well as analysis of the particulate for metals, sulfate, nitrate, carbon, etc. that helps to determine what is the main cause of the particulate concentrations. These data (including the different chemical analysis that are performed) are not collected with EPA approved reference or equivalent methods, but rather methods designed specifically for this type of analyses and as such for PM2.5.  There is more uncertainty associated with these data. These data are generally not used for regulatory purposes but more for research and to assist in control strategy development. These samples are collected with 24-hr samplers midnight to midnight local standard time with different sampling frequencies depending on the site location.

⁶ "RD_503_Blanks_yyyy.ZIP" (PM Fine Speciation-Blanks) - The Blanks data files are for the PM2.5 speciation sites and parameters, and reflect the concentrations of the individual species determined for both “TRIP” and “FIELD”.   These data values are reported to AQS beginning in 2003.  These files use a different format - "RB" instead of RD.  The "503" in the file names also indicates this different format.

⁷ "RD_501_IMPROVE_yyyy.ZIP" (PM Fine Speciation–IMPROVE) - The “Interagency Monitoring of Protected Visual Environments” data for 1988 to 2004 (also available from http://vista.cira.colostate.edu/IMPROVE/) are available here in AQS format to simplify the combined analysis with the PM2.5 speciation data.  Data for earlier years not included in the table above are available upon request.

More information about PM2.5 monitoring methods can be found on EPA's Ambient Monitoring Technology Center web site at www.epa.gov/ttn/amtic. Information about the new PM rule is available at http://epa.gov/pm/actions.html.