Completed Rulemakings | Air Quality Division: Page 3 of 3

New Source Review—Ammonia

ADEQ accepted comments on the proposed rulemaking for the addition of a significant emission rate for ammonia, as a precursor in the formation of secondary fine particulate matter (PM2.5), in PM2.5 nonattainment areas in the State.


ADEQ proposed a definition of "significant" that varies from the Notice of Proposed Rulemaking (NPRM).  The definition of "significant" in the NPRM would have required minor sources of ammonia in PM2.5 nonattainment areas to obtain a Class II permit.  The definition of "significant" in the Rulemaking clarifies the rule language so that only major sources of ammonia in PM2.5 nonattainment areas will be required to obtain a permit.

Additionally, based on public comments received during the NPRM’s comment period, ADEQ updated incorporations by reference of 40 C.F.R. Part 51, Appendix W (“Appendix W”), which governs modeling, to incorporate the most current version. Additional proposed technical corrections were made to existing Articles 3 and 4 to improve clarity and consistency.

The rule amendment was submitted to the US Environmental Protection Agency (EPA) as a revision the Arizona State Implementation Plan pursuant to Clean Air Act § 110 (42 U.S.C. § 7410).


  • Current Rules | View>
  • Notice of Docket Opening | View >
  • Notice of Proposed Rulemaking | View >
  • Arizona State Implementation Plan Revision: Determination of a Significant Emission Rate for Ammonia | View >
  • Notice of Supplemental Proposed Rulemaking | Go to Secretary of State's Page >
  • SIP Revision: New Source Review -- Significant Emission Rate for Ammonia in PM2.5 Nonattainment Areas | View >
  • Notice of Final Rulemaking | View >
  • Effective Date: Feb. 1, 2020 

Additional Information

Governor’s Regulatory Review Council (GRRC) Study Session and Council Meeting Agendas, Meeting Documents, including PDF copies of materials provided to GRRC for rulemakings, and Minutes | Visit GRRC Page >