; or (ii) to restore, maintain, or improve the reliability of operations at, or the safety of, the source, except, with respect to either clause (i) or (ii), when the change would be a modification as defined in subparagraph (A) and the Administrator determines that the increase in the maximum achievable hourly emission rate of a pollutant from such change would cause an adverse effect on human health or the environment. . (b) Clarification of definition of construction for prevention of significant deterioration Section 169(2) of the Clean Air Act ( 42 U.S.C. 7479(2) ) is amended by striking subparagraph (C) and inserting the following: (C) The term construction , when used in connection with a major emitting facility, includes a modification (as defined in section 111(a)) at such facility, except that for purposes of this subparagraph a modification does not include a change at a major emitting facility that does not result in a significant emissions increase, or a significant net emissions increase, in annual actual emissions at such facility. . (c) Clarification of definition of modifications and modified for nonattainment areas Section 171 of the Clean Air Act ( 42 U.S.C. 7501 ) is amended by striking paragraph (4) and inserting the following: (4) The terms modifications and modified mean a modification as defined in section 111(a)(4), except that such terms do not include a change at a major emitting facility that does not result in a significant emissions increase, or a significant net emissions increase, in annual actual emissions at such facility. . (d) Rule of construction Nothing in this section or the amendments made by this section shall be construed to treat any change as a modification for purposes of any provision of the Clean Air Act ( 42 U.S.C. 7401 et seq. ) if such change would not have been so treated as of the day before the date of enactment of this Act. 9. Prohibitions on use of social cost of greenhouse gas estimates (a) In general In promulgating regulations, issuing guidance, or taking