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Note: EPA no longer updates this information, but it may be useful as a reference or resource.

Please see www.epa.gov/nsr/ for the latest information on EPA's New Source Review program.

June 12, 1984 Significance Levels for Air Quality Impact as Outlined in Section III.A. of 40 CFR 51, Appendix S 7.6

Letter discusses when significance levels could be used such as in determining whether new source impacts are existing NAAQS or increment violation, or in cases where the impact of the new source is the first incremental impact that carries the total air quality above the increment or standard.

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