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PART A
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I.B. Definitions
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CONCERNING GENERAL PROVISIONS APPLICABLE TO REPORTING AND
PERMITTING
I.B.44. Subject to Regulation
For any air pollutant, that the pollutant is subject to either a provision in the Federal Act, or a nationally-applicable regulation codified by the Administrator in Subchapter C of 40 CFR Chapter
I of the Federal Act, that requires actual control of the quantity of emissions of the pollutant, and that such a control requirement has taken effect and is operative to control, limit or restrict the quantity of emissions of that pollutant released from the regulated activity, except that:
I.B.44.a. GHG shall not be subject to regulation except as provided in Sections
I.B.44.d. through f. of this Part A.
I.B.44.b. For purposes of Section I.B.44.c. through e., the term CO2e of this Part
A, shall represent an amount of GHG emitted, and shall be computed as follows:
I.B.44.b.(i) Multiplying the mass amount of emissions (tpy), for each of the six GHGs in the pollutant GHG, by the gas’s associated GWP published at Table A-1 to Subpart A of Part 98 of 40 CFR as in effect November
29, 2013, which is hereby incorporated by reference, but not including later amendments. For purposes of this paragraph, prior to July 21,
2014, the mass of the greenhouse gas carbon dioxide shall not include carbon dioxide emissions resulting from the combustion or decomposition of non-fossilized and biodegradable organic material originating from plants, animals, or micro-organisms (including products, by-products, residues and waste from agriculture, forestry and related industries as well as the non-fossilized and biodegradable organic fractions of industrial and municipal wastes, including gases and liquids recovered from the decomposition of non-fossilized and biodegradable organic material).
I.B.44.b.(ii) Sum the resultant value from Section I.B.44.b.(i) of this Part A, for each gas to compute a tpy CO2e.

I.B.44.c. The term emissions increase as used in Sections I.B.44.d. through e. of this Part A, shall mean that both a significant emissions increase (as calculated using the procedures in Section II.A.23 of Part D) and a significant net emissions increase (as defined in Sections II.A.26, and II.A.44 of Part D) occur. For the pollutant GHG, an emissions increase shall be based on tpy CO2e, and shall be calculated assuming the pollutant GHG is a regulated NSR pollutant, and significant is defined as 75,000 tpy CO2e instead of applying the value in Section
II.A.44.b. of Part D.
I.B.44.d. Beginning January 2, 2011, the pollutant GHG is subject to regulation concerning major stationary source new source review and prevention of significant deterioration if:
I.B.44.d.(i) The stationary source is a new major stationary source for a regulated NSR pollutant that is not GHG, and also will emit or will have the potential to emit 75,000 tpy CO2e or more; or
I.B.44.d.(ii) The stationary source is an existing major stationary source for a regulated NSR pollutant that is not GHG, and also will have an emissions increase of a regulated NSR pollutant, and an emissions increase of
75,000 tpy CO2e or more.
I.B.44.e. Repealed.
Repealed.I.B.44.f. If there is a change in federal law that supersedes, or the District of Columbia Circuit Court of Appeals or the United States Supreme Court directs or issues an order, which limits or renders ineffective the regulation of GHG emissions at stationary sources under the New Source Review Prevention of
Significant Deterioration(PSD) or Title V provisions of the Federal Act the regulation, GHG emissions under the corresponding programs in this Regulation
Number 3 shall be limited or rendered ineffective to the same extent.
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PART G STATEMENTS OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE
I.AAA. Adopted: January 21, 2016
Regulation Number 3, Part A, Section I.B.44. – revising GHG permitting thresholds.
This Statement of Basis, Specific Statutory Authority and Purpose complies with the requirements of the
Colorado Administrative Procedure Act Sections 24-4-103, C.R.S., the Colorado Air Pollution Prevention and Control Act Sections 25-7-110 and 25-7110.5, C.R.S. (“the Act”), and the Air Quality Control
Commission’s (“Commission”) Procedural Rules.
Basis
The Commission revised the definition of “subject to regulation” to correspond to revisions to the federal definition of subject to regulation.
Specific Statutory Authority
The Colorado Air Pollution Prevention and Control Act, Sections 25-7-105(1)(a), 25-7-201 though 25-7-
206, 25-7-210, 25-7-301, and 25-7-302, C.R.S. authorize the Commission to promulgate a comprehensive State Implementation Plan (“SIP”) which will assure attainment and maintenance of

national ambient air quality standards (“NAAQS”) and prevent significant deterioration (“PSD”) of air quality in conformance with the Federal and Colorado Acts. Section 25-7-105(1)(c) further requires the
Commission to promulgate a PSD program in conformity with federal requirements, including definitions that do not differ from the federal definitions.
Purpose
In 2014, the United States Supreme Court held that EPA could not treat GHG as a pollutant for purposes of defining a “major emitting facility” (or a “modification” thereof) for Prevention of Significant Deterioration
(“PSD”) or a “major source” for Title V, essentially invalidating the Step 2 GHG permitting thresholds in
EPA’s Tailoring Rule. (see Util. Air Regulatory Grp. v. EPA, 134 S. Ct. 2427 (2014)) In 2015, the Court of
Appeals vacated EPA regulations to the extent that they required a stationary source obtain a PSD or
Title V permit solely because the source emitted GHG in excess of applicable GHG-major source thresholds. (see Coalition for Responsible Regulation v. EPA, Nos. 09-1322, 10-073, 10-1092, 10-1167
(2015)) On August 19, 2015 (80 Fed. Reg. 50199), EPA issued a final rule that removed the Step 2 GHG permitting thresholds from the definitions of subject to regulation at 40 CFR Sections 51.166 and 52.21.
In response to the court decisions and EPA’s corresponding revisions, the Commission revised Section
I.B.44.e. to correspond to the federal definition of subject to regulation.
Further, the Commission corrected any typographical, grammatical and formatting errors found within the regulation.