EPA is proposing to clarify the process for evaluating whether the New Source Review (NSR) permitting program would apply to proposed projects at existing air pollution sources. This proposal would make it clear that both emissions increases and decreases from a major modification at an existing source are to be considered during Step 1 of the two-step NSR applicability test. This process is known as project emissions accounting (previously referred to as project netting.)You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.