Mind, data collection agencies have up to 6 months to report their data. Twice per year in the spring and fall (late May and November). The size of the (zipped) file, the number of data rows in the file,Īnd the date the file was last modified. The annual summary files are small enough to include all data in one file.Įach group has data listed by year, in reverse order, back to 1990.Įach table entry has the file name, linked to the file,

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

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

These are the standard time aggregations EPA calculates and stores Some contain raw data (sample data as reported). Some contain data summarized on a daily basis (daily summary), and

Some contain data summarized on an annual basis (annual summary files), The data available here is also available via Understand the EPA ambient air quality monitoring program and data. This page contains large files of data intended for use by people who

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). This page contains pre-generated files of data available for download.

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