Air Data - Frequent Questions
- How do I cite data or graphics obtained from the AirData website?
- I used to be able to get emissions data from the AirData website, but the site has changed. Where can I find that information now?
- I used to be able to generate nonattainment area maps on the AirData website, but the site has changed. Where can I get that information now?
- What is an exceptional event?
- Does the exclude exceptional events option exclude only EPA regionally-concurred exceptional events or all flagged events?
- In the CSV files, are the exceptional events data indicated?
- How do the reports handle co-located PM2.5 monitors?
- Does a PM2.5 query pull only data from monitors with a parameter code of 88101 or does it include others such as 88501?
- Do the AQI calculations include Non-FEM/FRM continuous PM2.5 data?
- If there's more than one monitor in a county, does the tile plot take the max AQI value among all the monitors in the county?
- Can you get design values from AirData?
- What is the AQS Data Mart?
- Do all AQI plots use the most current AQI breakpoints - regardless of what year you request?
- What is the lag between the data being posted on AQS and it being used in AirData?
- Are the chemical speciation data parameters available from AirData?
- How do AirData and AirNow differ?
Please use the following citation:
US Environmental Protection Agency. Air Quality System Data Mart [internet database] available via https://19january2021snapshot.epa.gov/airdata. Accessed Month DD, YYYY.
At this time, the best sources for emissions data are:
- Air Emissions Inventories website - all National Emissions Inventory data, including facility-level HAP data
- Air Emission Sources website - criteria pollutant summaries
At this time, the best source for nonattainment area maps is the EPA Greenbook Website.
Exceptional Events are unusual or naturally occurring events that can affect air quality but are not reasonably controllable using techniques that tribal, state or local air agencies may implement in order to attain and maintain the National Ambient Air Quality Standards. For more information, see Treatment of Data Influenced by Exceptional Events.
Choosing the “Exclude exceptional events data” option excludes all flagged exceptional events, regardless of concurrence. Longer answer – States can flag data that may have been influenced by an exceptional event (e.g. high winds, wildfire). As a user of AirData, you can choose to exclude these flagged data. This option is available in the Air Quality Statistics Report and Monitor Values Report. In the Air Quality Statistics Report, there is not a way to tell which, if any, statistics are affected by including/excluding exceptional events. However, in the Monitor Values Report, there is a column that indicates whether there were any flagged data ('NONE'), whether flagged data were included ('INCLUDED') or excluded ('EXCLUDED').
In the Air Quality Statistics Report, there is not a way to tell which, if any, statistics are affected by including/excluding exceptional events. However, in the Monitor Values Report, there is a column that indicates whether there were any flagged data ('NONE'), whether flagged data were included ('INCLUDED') or excluded ('EXCLUDED'). This field is in the CSV file also.
Each site-poc is treated as a separate monitor. To see an example of this, you can use the Concentration Plot tool for PM2.5.
Reports providing annual summary statistics the Air Quality Statistics Report and Monitor Values Report use only PM2.5 data reported as parameter code 88101 (PM2.5 LOCAL CONDITIONS). Reports and visualization tools providing AQI data use both 88101 and 88502 (ACCEPTABLE PM2.5 AQI & SPECIATION MASS). This methodology is consistent with the AQI and how standard AQS reports are generated. The Concentration Plot also pulls both 88101 and 88502, and the data for each parameter are plotted separately.
Yes, PM2.5 data reported as parameter code 88101 (PM2.5 LOCAL CONDITIONS) and 88502 (ACCEPTABLE PM2.5 AQI & SPECIATION MASS) are used in the AQI summaries on AirData.
Yes. AQI displays/reports always use the maximum daily AQI value in the geographic region represented.
At this time, design values are not available from AirData. Design values can be obtained from AQS.
The AQS Data Mart is a database containing all of the information from the AQS system. The AQS Data Mart was built as a storehouse of air quality information that allows users to make queries of unlimited quantities of data while not affecting the primary AQS database. For more information, see the AQS Data Mart page.
Yes. Every AQI summary (report, graph, etc.) from AirData is based on the current AQI breakpoints regardless of year. See 40 CFR Part 58 Appendix G Exit and the Technical Assistance Document for the Reporting of Daily Air Quality – the Air Quality Index (AQI) for details.
The AQS Data Mart is updated every Sunday night. So the data provided via AirData never lags AQS by more than a week.
Note regarding timeliness of data submitted to AQS: AQS contains ambient air pollution data collected by EPA, state, local, and tribal air pollution control agencies. Most data in AQS is required to be submitted by the end of the calendar quarter after the quarter in which it was collected. However, AQS is updated practically every day as reporting agencies have data ready to submit. A key milestone in reporting is May 1st, by which all data for the prior year should be complete and correct.
Currently, you can access daily and annual summary chemical speciation data from the Chemical Speciation Network layer in the Interactive Map of Air Quality Monitors. There are also pre-pulled files of speciation data available on the Download Data Files page and by using the query tool on the Download Raw Data page.
AirData provides monitoring data from AQS which can date back to 1980 depending on the pollutant, so you can do retrospective analyses with a number of pollutants. AirNow reports real-time and forecast air quality data with respect to the Air Quality Index, mostly based on ozone and PM2.5 concentrations. While there is some archive data available on the AirNow website, its primary purpose is to report what’s happening now and what is forecast to happen tomorrow.