Add datasets for Community Multiscale Air Quality (CMAQ) Ozone and PM 2.5

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What type of need does this dataset address?
Local air quality data indexed by census tract (not zip code)

If there is a specific dataset that meets this need, please specify it.
Describe the name, provider, license location, and IRI of the dataset. If the dataset does not have a specific license, please indicate why you think it is publicly available, and who is the authority publishing the dataset.

From Andrew Lawson: The EPA stores CMAQ estimates for daily Ozone and PM 2.5 at various scales. They have data files at https://www.epa.gov/hesc/rsig-related-downloadable-data-files#faqsd. Most of the files are for 12 Km grids but they also have (or had) census tract (CT) estimates.

Looks like the best site per first comment below will be https://www.caces.us/data.

Generally speaking EPA and other US government data is freely available.

Describe other options for this kind of data
If you don't have a specific data set in mind, provide a clear and concise description of any alternative datasets or sources you've considered.

If these are not now available then they can be reconstructed from gridded data. I am checking on the availability currently.

Additional context
Add any other context about the dataset request here. In particular, if you are an expert on this dataset, or can recommend someone who is, please make that clear.

Virtually all our spatial work is at CT or block group (BG) level. Zipcodes can change quite a lot and so they are not used. In the 2010 census the zipcodes were matched to the CTs and ZCTAs were produced. However it is simpler to stick with CTs and BGs in general. FIPS codes can be used to locate the CTS or BGs

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Additional information from Andrew via Melissa:

I have made further checks at EPA and the best resolution for the CMAQ data is 12 km grid. However the CACES site has CT and BG level estimates for a range of chemicals for a range of years based on land us regression (LUR). The site address is https://www.caces.us/data This means we can get a range of pollutants for AACES1 and AACES2 based on these data.
More accurate estimates could also be obtained. A former PhD student of mine (Matt Bozigar) has offered to supply his R code to process the 12 km grid data for CTs from CMAQ if we need that accuracy.