This page contains pre-generated files of data available for download. The files are updated twice per year: once in June to capture the complete data for the prior year and once in December to capture the data for the summer (ozone season).

Site and Monitor Descriptions

Table of Annual Summary Data

Tables of Daily and Daily Summary Data

Tables of Daily AQI

Tables of Hourly Data

Tables of 8-Hour Average Data

Table of Blanks Data

About the data

Description of data and formats

This page contains large files of data intended for use by people who understand the EPA ambient air quality monitoring program and data. Other sources of data are available.

The data available here is also available via an API.

Some contain data summarized on an annual basis (annual summary files), some contain data summarized on a daily basis (daily summary), and some contain raw data (sample data as reported). These are the standard time aggregations EPA calculates and stores (we do not have monthly data). All but the annual summary have data files grouped by parameter:

Criteria Gases

Particulates

Meteorological

Toxics (see "Notes on Toxics" below), Ozone Precursors, and Lead

Blanks (Blanks are empty cannisters that are measured for speciation quality assurance reasons)

The annual summary files are small enough to include all data in one file.

Each group has data listed by year, in reverse order, back to 1990.

Each table entry has the file name, linked to the file, the size of the (zipped) file, the number of data rows in the file, and the date the file was last modified. EPA will update these files twice per year; in the spring and fall (late May and November). Keep in mind, data collection agencies have up to 6 months to report their data.

The files are all comma separated text with a header. Each aggregate level has a different format.

Notes on Toxics.

1. While this page contains information on toxics, it is suggested you get toxics data from the EPA toxics archive. It is a value added product that includes additional data quality assurance and reduction. The toxics data is included on this page for those needed it in a consistent format with other AQS data.

2. EPA has several ways of grouping parameters. For the parameters listed here as toxics we have included two groups of parameters: Core HAPS (Hazardous Air Pollutants) and VOCs ( Volatile Organic Compounds). The VOC list was expanded with the December 2015 update. These lists include the parameters as defined in the EPA AQS system as "CORE HAPS" or "VOC". You can view the list of parameters included in either catagory by visiting the AQS Code Tables page for Parameter Classes and searching for CORE_HAPS or VOC.

The Air Quality Index (AQI) values are presented in several files. AQI is calculated each day for each monitor for the Criteria Gases and PM10 and PM2.5 (FRM and non FRM). The AQI values are on the respective records in those Daily Summary files. There are also annual summary AQI files that show by CBSA (metro area) or county the annual statistics for AQI (max, number of values in each category, etc.). This file has one record per year per CBSA or county. There are also daily summary files that show the AQI by CBSA or county. These have one record per day per CBSA or county.

For reference, there is also a file listing all of the files on this page and the date they were modified. Each file also includes the last change date of each record in the file.



Annual Summary Data