An official website of the United States government.

We've made some changes to EPA.gov. 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.

Clean Air Status and Trends Network (CASTNET)

Contact Us

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.

Clean Air Status and Trends Network (CASTNET)

Monitoring

Download Data

Maps & Charts

Publications

What's New

  • COVID-19 Update: We are working closely with CASTNET operators, calibrators, and laboratory personnel to protect their safety and the health of their families. During an emergency or COOP, ambient air monitoring programs are a mission essential function and should continue, but we may experience gaps in the data record as local directives prohibit operators from visiting the sites. Currently, most CASTNET sites are continuing to operate following standard procedures and schedules. Data will continue to be flagged following the procedures in the QAPP and completeness criteria applied to aggregate data products. Updates will be provided if we experience a degradation in service.

  • The 2018 CASTNET Annual Report is now available. Read about the significant decreases in sulfur and nitrogen pollutant concentrations since 1990. Ozone concentrations measured by CASTNET in the Eastern and Western U.S. were slightly higher in 2018 than 2017.
  • Recent Network Updates:
    • In November 2019, a monitoring site at Crater's of the Moon National Monument and Preserve (CRM435) joined CASTNET.
    • In July 2019, Grand Teton National Park (GRT434) joined CASTNET.
    • In April 2019, Death Valley National Monument (DEV412) was added to CASTNET. This site was also operated by the National Park Service from 1995-2007.

Contact Us to ask a question, provide feedback, or report a problem.