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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.

September 18, 1989 Request for Clarification of Policy Regarding the "Net Emissions Increase" 4.41 4.39

Memo provides general guidance on four questions of net emissions increases:

(a) If an emissions increase from a proposed modification is less than significant, the Agency need not consider whether a contemporaneous net emissions increase has occurred. The 1983 memo that discussed this, entitled "Net Emission Increases under PSD," is still an appropriate resource (No. 4.24).

(b) The criteria used to determine if a significant net emissions increase has occurred from a proposed modification at an existing major source are applied on a pollutant-by-pollutant basis.

(c) When determining PSD applicability, the comparison of prior "actual" versus new "potential" emissions (or "allowable" where appropriate) is the correct methodology to use.

(d) Except for emissions changes considered in issuing a PSD permit, all emissions points at the source are reviewed in terms of actual emissions changes to determine the contemporaneous emissions changes at a source, including those emissions points that have not had emissions changes incorporated into State permits.

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