Section 203.1260  Net Emissions Increase

a)         "Net emissions increase" means, with respect to any regulated NSR pollutant emitted by a major stationary source, the amount by which the sum of the following exceeds zero:

1)         The increase in emissions from a particular physical change or change in the method of operation at a stationary source as calculated pursuant to Section 203.1410(c); and

2)         Any other increases and decreases in actual emissions at the major stationary source that are contemporaneous with the particular change and are otherwise creditable. Baseline actual emissions for calculating increases and decreases under this Section shall be determined as provided in Section 203.1070, except that Section 203.1070(a)(3) and Section 203.1070(b)(4) shall not apply.

b)         The following steps determine whether the increase or decrease in emissions is available.

1)         Except for increases or decreases in VOM and NO_X emissions in serious and severe ozone nonattainment areas which are addressed in Section 203.1370(c), an increase or decrease in actual emissions is contemporaneous only if it occurs between the date that an increase from a particular change occurs and the date five years before a timely and complete application is submitted for the particular change.  It shall also occur after either April 24, 1979, or the date the area is designated by the USEPA as a nonattainment area for the pollutant, whichever is more recent.

2)         An increase or decrease in actual emissions is creditable:

A)        Only if there is not in effect for the source at the time the particular change occurs, a permit issued under this Part which relied on the same increase or decrease in actual emissions; and

B)        Only to the extent the new and old levels differ.

3)         A decrease in actual emissions is creditable only to the extent that:

A)        It is enforceable as a practical matter at and after the time that actual construction on the particular change begins;

B)        It has approximately the same qualitative significance for public health and welfare as that attributed to the increase from the particular change;

C)        The old level of actual emissions or the old level of allowable emissions, whichever is lower, exceeds the new level of actual emissions; and

D)        The Agency has not relied on it in issuing any permit under 35 Ill.  Adm.  Code 201.142 or 201.143 or this Part or 35 Ill. Adm. Code 204 or 40 CFR 52.21 and has not relied on it for demonstrating attainment or reasonable further progress.

4)         An increase that results from a physical change at a source occurs when the emissions unit on which construction occurred becomes operational and begins to emit a particular pollutant.  Any emission unit that replaces an existing emissions unit that requires shakedown becomes operational only after a shakedown period, not to exceed 180 days.

5)         Section 203.1040(b) shall not apply for determining creditable increases and decreases after a change.

(Source:  Added at 49 Ill. Reg. 6237, effective April 23, 2025)