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Complying with Air Emissions Standards for Stationary Sources

  • Compliance and Applicability under CAA 111, 112, and 129

    Access EPA responses issued after May 2019. 

  • Applicability Determination Index

    Access EPA responses issued before May 2019.

About the Applicability and Compliance Dashboard

The Applicability and Compliance dashboard contains EPA responses to applicability and compliance issues associated with certain stationary source programs under Clean Air Act CAA sections 111, 112, and 129, such as New Source Performance Standards and National Emissions Standards.

Users can search by a particular facility or requestor name, a specific regulation, or by keywords. 

The dashboard houses EPA determinations signed since May 2019.

About the Applicability Determination Index

To ensure national consistency in implementing the NSPS and NESHAP programs, EPA maintains a compilation of such letters and memoranda since they were first issued in the Applicability Determination Index (ADI).

The ADI contains "regulatory interpretations" which are written responses that apply to the broad range of NSPS and NESHAP regulatory requirements as they pertain to a whole source category. Users can search by date, office of issuance, subpart, citation, control number, or keyword searches.

The ADI houses EPA determinations signed before May 2019. 

Regional Office Contact

To find more information about CAA permitting authorities, focus topics, and current actions, please contact your EPA Regional Office. 

Contact Us to ask a question, provide feedback, or report a problem.
Last updated on March 10, 2025
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