(1)

by inserting (A) before The term;

(2)

by adding at the end the following: For purposes of the preceding sentence, a change increases the amount of any air pollutant emitted by such source only if the maximum hourly emission rate of an air pollutant that is achievable by such source after the change is higher than the maximum hourly emission rate of such air pollutant that was achievable by such source during any hour in the 10-year period immediately preceding the change.; and

(3)

by adding at the end the following:

(B)

Notwithstanding subparagraph (A), the term modification does not include a change at a stationary source that is designed—

(i)

to reduce the amount of any air pollutant emitted by the source per unit of production; 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.

(a) Applicability to construction activities

Section 165 of the Clean Air Act (42 U.S.C. 7475) is amended by adding at the end the following:

(f) Applicability to construction

(1) In general

The requirements of subsection (a) that apply with respect to authorizing construction of a major emitting facility shall apply only with respect to construction that involves physical construction of the discrete parts of an emissions unit at a major emitting facility, regardless of whether the construction involves other physical on-site activities at the major emitting facility, including any such other physical on-site activity that—

(A)

may be costly;

(B)

may significantly alter the site;

(C)

is permanent in nature; or

(D)

is to accommodate an installation to an emissions unit.

(2) Definition of emissions unit

In this subsection, the term emissions unit means any part of a stationary source that emits, or has the potential to emit, any air pollutant that is regulated under this title.

(b) Definition

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.

(a) Definition

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), 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.

(b) Applicability to construction

Section 172(c)(5) of the Clean Air Act (42 U.S.C. 7502(c)(5)) is amended by adding at the end the following:

The construction for which a permit is required under this paragraph is construction that involves physical construction of the discrete parts of an emissions unit (as defined in section 165(f)(2)) at a major stationary source, regardless of whether the construction involves other physical on-site activities at the major stationary source, including any such other physical on-site activity that—

(A)

may be costly;

(B)

may significantly alter the site;

(C)

is permanent in nature; or

(D)

is to accommodate an installation to an emissions unit.