Clean Air Status and Trends Network (CASTNET)
CASTNET is a national monitoring network established to assess trends in pollutant concentrations, atmospheric deposition, and ecological effects due to changes in air pollutant emissions. See the CASTNET overview fact sheet and the CASTNET Ozone Monitoring page for more information.
What's New
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The NPS-sponsored CASTNET site at Petrified Forest National Park (PET427), AZ will be decommissioned due to recently discovered artifacts near the monitoring site. Sampling was discontinued on 12/31/2023.
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Due to budget challenges, the National Park Service discontinued SO2 measurements at the NPS-sponsored CASTNET sites on August 1, 2023. The recent change in the filter pack suite of measurements at the NPS sites will impact trend analyses and map products.
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EPA suspended operations at a number of CASTNET locations throughout the country in May, 2022 due to budget constraints. These sites included: ASH135, UND002, WST109 (sampling resumed in late 2023), HWF187, CDR119, PSU106 (ozone continues), CDZ171, PNF126, ANA115 (ozone continues), and DCP114. The CASTNET program currently is undergoing an independent scientific review.