An official website of the United States government.

Due to a lapse in appropriations, EPA websites will not be regularly updated. In the event of an environmental emergency imminently threatening the safety of human life or where necessary to protect certain property, the EPA website will be updated with appropriate information. Please note that all information on the EPA website may not be up to date, and transactions and inquiries submitted to the EPA website may not be processed or responded to until appropriations are enacted.

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.

Reclassification of Major Sources as Area Sources Under Section 112 of the Clean Air Act

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.