Data source: United States Environmental Protection Agency (EPA). <aqs.epa.gov/aqsweb/airdata.download_files.html>
The file returned will have a column for each pollutant; the value will be an average of monthly estimates over the specified time period.
Choose .csv file with Latitude and Longitude columns. A sample input file can be downloaded here.
Greenblatt RE, Himes BE. Facilitating Inclusion of Geocoded Pollution Data into Health Studies. AMIA Jt Summits Transl Sci Proc. 2019;2019:553–561.(PMID: 31259010 ). GITHUB repository.