Increases ‘entirely offset’ are no longer increases.

Finally, as noted above, the PSD and NSR provisions of the statute reference the definition of "modification" in the NSPS provision. 42 U.S.C. § § 7479(2)(C), 7501(4). That provision defines "modification" as "any physical [*33] change in, or change in the method of operation of a stationary source which increases the amount of any air pollutant emitted by such source or which results in the emission of any air pollutant not previously emitted." 42 U.S.C. § 7411(a)(4). The 1978 PSD regulations defined "modification" as a "major modification," that is, a change that resulted in an emissions increase of 100 or 250 tons per year (depending on the pollutant). This threshold was incorporated from the statutory definition of "major emitting facility." This Court rejected that approach. 606 F.2d at 1081. Instead, the Court said that a "modification" occurs whenever there is an increase "in Any amount" [sic] of the pollutants emitted. Id. 5Link to the text of the note The Court also held that any emissions increase that is entirely offset by contemporaneous emission reductions at the source would not be considered a modification. Id.