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On Jan. 25, 2018, U.S. EPA issued a guidance memo regarding the applicability of U.S. EPA’s maximum achievable control technology (MACT) standards. This guidance supersedes the May 1995 Seitz Memorandum, and pursuant to the Federal Register notice, became effective on Feb. 8, 2018.

Under the new guidance, if you historically reduced your emissions to below the major source MACT standard’s applicability thresholds, you are no longer required to comply with the major source MACT standard. Depending on your reduced emission levels, this means you can now comply with the less stringent area source MACT standard; or, in some cases, no MACT standard would apply.

The new guidance also means that facilities/sources that accepted operational restrictions to avoid being subject to a major source MACT standard may no longer be subject to Title V permitting or may be able to discontinue using MACT-required HAP controls.

More information about the withdraw of the Once in Always In policy, along with guidance on how to take advantage of the change, can be found at:

This fact sheet explains the new guidance and will help you determine if it applies to your operations. It also outlines the next steps and other considerations for you to determine if your Title V permit requirements can be reduced under the new guidance.

For more information, please contact Briana Mastriana, Division of Air Pollution Control, MACT Coordinator, at or (614) 644-3698.