# 35 Ill. Adm. Code 203.208: Section 203.208 Net Emission Determination > Illinois · Regulations · In force URL: https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_208 ## Section - **Citation:** 35 Ill. Adm. Code 203.208 - **Heading:** Section 203.208 Net Emission Determination - **Jurisdiction:** Illinois - **Kind:** Regulations - **Status:** In force - **Text as of:** August 14, 2026 - **Source:** Compiled text - **Location:** Illinois Administrative Code / Title 35 ENVIRONMENTAL PROTECTION / CHAPTER I: POLLUTION CONTROL BOARD / Part 203 MAJOR STATIONARY SOURCES CONSTRUCTION AND MODIFICATION / Section 203.208 Net Emission Determination ## Text Section 203 Section 203.208  Net Emission Determination A net emissions increase is the amount by which the sum of any increase in actual emissions from a particular physical change or change in method of operation at a source, and any other increases and decreases in actual emissions at the source that are contemporaneous with the particular change and are otherwise creditable, exceeds zero.  The following steps determine whether the increase or decrease in emissions is available. a)         Except for increases or decreases in volatile organic material and nitrogen oxide emissions in serious and severe ozone nonattainment areas which are addressed in Section 203.209(b), 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 must also occur after either April 24, 1979, or the date the area is designated by the United States Environmental Protection Agency as a nonattainment area for the pollutant, whichever is more recent. b)         An increase or decrease in actual emissions is creditable: 1)         Only if there is not in effect for the source at the time the particular change occurs a permit which relied on the same increase or decrease in actual emissions; and 2)         Only to the extent the new and old levels differ al Protection Agency as a nonattainment area for the pollutant, whichever is more recent. b)         An increase or decrease in actual emissions is creditable: 1)         Only if there is not in effect for the source at the time the particular change occurs a permit which relied on the same increase or decrease in actual emissions; and 2)         Only to the extent the new and old levels differ. c)         A decrease in actual emissions is creditable to the extent that: 1)         It is federally enforceable at and after the time that actual construction on the particular change begins; 2)         It has approximately the same qualitative significance for public health and welfare as that attributed to the increase from the particular change; 3)         The old level of actual emissions or the old level of allowable emissions, whichever is lower, exceeds the new level of actual emissions; and 4)         It is demonstrated by the Agency not to have been previously relied on in issuing any permit pursuant to this Part or 35 Ill. Adm. Code 201.142 or 201.143 or for demonstrating attainment or reasonable further progress in the nonattainment area which the particular change will impact. d)         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 replacement unit that requires shakedown becomes operational only after a shakedown period not to exceed 180 days. ## Nearby sections - [35 Ill. Adm. Code 203.201 Section 203.201 Prohibition](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_201.md) - [35 Ill. Adm. Code 203.202 Section 203.202 Coordination with Permit Requirement and Application Pursuant to 35 Ill. Adm. Code 201](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_202.md) - [35 Ill. Adm. Code 203.203 Section 203.203 Construction Permit Requirement and Application](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_203.md) - [35 Ill. Adm. Code 203.204 Section 203.204 Duration of Construction Permit (Repealed)](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_204.md) - [35 Ill. Adm. Code 203.205 Section 203.205 Effect of Permits](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_205.md) - [35 Ill. Adm. Code 203.206 Section 203.206 Major Stationary Source](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_206.md) - [35 Ill. Adm. Code 203.207 Section 203.207 Major Modification of a Source](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_207.md) - [35 Ill. Adm. Code 203.208 Section 203.208 Net Emission Determination](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_208.md) - [35 Ill. Adm. Code 203.209 Section 203.209 Significant Emissions Determination](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_209.md) - [35 Ill. Adm. Code 203.210 Section 203.210 Relaxation of a Source-Specific Limitation](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_210.md) - [35 Ill. Adm. Code 203.211 Section 203.211 Permit Exemption Based on Fugitive Emissions](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_211.md) --- Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_208. Check the current official text before relying on it. Not legal advice.