On January 25, 2018, EPA issued a guidance memorandum withdrawing the “once in always in” policy for the classification of major sources of hazardous air pollutants under section 112 of the Clean Air Act. With the new guidance, sources of hazardous air pollutants previously classified as “major sources” may be reclassified as “area” sources at any time, provided the facility limits its potential to emit below major source thresholds.You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.
Memorandum: Reclassification of Major Sources as Area Sources under Section 112 of the Clean Air Act (PDF)(4 pp, 4 MB,
January 25, 2018)
This memorandum withdraws the “once in always in” policy.
Potential to Emit for MACT Standards -- Guidance on Timing Issues (PDF)(6 pp, 67 K,
May 16, 1995)
This document is part of the Title V Policy and Guidance Database