An official website of the United States government.

We've made some changes to If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.


Data Use and Citation

CASTNET data is available in many formats on this website. Data is updated daily so you should note the date that data was accessed. Data tables include Quality Rating codes to identify validation status (e.g., Levels 1 through 3) and will also be subject to changes or updates.

We encourage the use and publication of CASTNET data in scientific, policy-related, or educational activities. Any published use of CASTNET data or information must acknowledge CASTNET as the source. A suggested citation is:

U.S. Environmental Protection Agency Clean Air Markets Division
Clean Air Status and Trends Network (CASTNET)
[Data table(s) accessed (i.e., Hourly Ozone, Annual Total Deposition)]
Available at
Date accessed: [month day, year]

We request that the author provide EPA (puchalski.melissa(at) the URL or the PDF for publications using CASTNET data. We also encourage educators to send the EPA a brief description of how they use the CASTNET data in their curriculum.