View Rule

Under the New Source Review (NSR) pre-construction permitting program, sources undergoing modifications need to determine whether their modification is considered a major modification and thus subject to the major NSR pre-construction permitting program. A source owner determines if its source is undergoing a major modification under NSR using a two-step applicability test. The first step is to determine if there is a significant emission increase” of a regulated NSR pollutant from the proposed modification (Step 1) and the second step is to determine if there is a 'significant net emission increase’ of that pollutant (Step 2). EPA proposed revisions that clarify that emissions increases and decreases from a modification are considered as part of Step 1 of the NSR major modification applicability test.