State Implementation Plans (SIPs)

The core focus of the air quality program is to implement, maintain, and enforce the National Ambient Air Quality Standards (NAAQS). Oklahoma’s SIP lays out the goals and procedures to protect the state’s air quality through the daily operations of AQD. It includes most of the Oklahoma Air Quality Rules and other strategies developed at the state level for implementing the various federal air quality programs and requirements. The federally enforceable SIP for Oklahoma is compiled in 40 CFR Part 52, Subpart LL.

The SIP covers many parts of the AQ program, such as PSD/NSR (and Minor Facility) Construction Permits and the Regional Haze Program.  Other portions of the AQ program are covered under separate but interrelated plans, such as Part 70/Title V (and Minor Facility) Operating Permits and the §111(d)/129 Plans for existing sources.  The SIP is regularly reviewed and amended as necessary to accommodate changes in State and Federal statutes, rules, policies, standards, and program requirements.

Infrastructure State Implementation Plans (I-SIPs) 

IntroductionOzone (O3)Particulate Matter (PM)Nitrogen Dioxide (NO2)Sulfur Dioxide (SO2)Lead (Pb)Carbon Monoxide (CO)

In addition to other SIP revisions, each time EPA issues or revises a NAAQS, the State is required to demonstrate that the SIP meets the “infrastructure” requirements of CAA Section 110(a)(2) (A)-(M) to attain and maintain the new NAAQS. Oklahoma’s “infrastructure SIP” (I-SIP) submittals developed under EPA guidance typically consist of a certification letter from the Oklahoma Secretary of Energy and Environment, and a §110(a)(2) checklist, along with documentation of the public notice, hearing, and comment process.

The I-SIP submittal documents and status for each NAAQS change are under the corresponding pollutant tab.

2015 Primary and Secondary Ozone NAAQS

Date Sent to EPA: October 25, 2018

EPA Action: Approved, March 30, 2020, 85 FR 17502

Docket Link: EPA–R06–OAR–2018–0786

  • Certification Letter
  • Checklist
  • Good Neighbor Support Document
  • Public Notice
  • Hearing Record: Notice of Hearing Cancellation
  • Comments: none received
2008 Primary and Secondary Ozone NAAQS

Date Sent to EPA: February 9, 2015

EPA Action: Approved, December 9, 2016, 81 FR 89008

Docket Link: EPA–R06–OAR–2012–0812

  • Certification Letter
  • Checklist
  • Public Notice
  • Hearing Record: Notice of Hearing Cancellation
  • Comments and Exhibits (Response to comments)
1997 Primary and Secondary Ozone NAAQS

Date Sent to EPA: December 5, 2007

EPA Action: Approved, January 26, 2012, 77 FR 3933

Docket Link: EPA–R06–OAR–2008–0637

  • Certification Letter
2012 Primary PM2.5 (transport only)

Date Sent to EPA: June 20, 2016

EPA Action: Approved, July 5, 2018, 83 FR 1330

Docket Link: EPA–R06–OAR–2017–0052

  • Certification Letter
  • Technical Support Document
  • Public Notice
  • Hearing Record: Notice of Hearing Cancellation
  • Comments: none received
2012 Primary PM2.5 (except transport)

Date Sent to EPA: June 20, 2016

EPA Action: Approved, June 14, 2017, 82 FR 27121

Docket Link: EPA–R06–OAR–2015–0142

  • Certification Letter
  • Checklist
  • Public Notice
  • Hearing Record: Notice of Hearing Cancellation
  • Comments: none received
2006 Primary and Secondary PM2.5

Date Sent to EPA: June 24, 2010

EPA Action: Approved, January 26, 2012, 77 FR 3933

Docket Link: EPA–R06–OAR–2008–0637

  • Certification Letter
  • Checklist
  • Comments: none received
1997 Primary and Secondary PM2.5

Date Sent to EPA: April 5, 2011

EPA Action: Approved, January 26, 2012, 77 FR 3933

Docket Link: EPA–R06–OAR–2008–0637

  • Certification Letter
  • Checklist
  • Comments: none received
2010 Primary NO2

Date Sent to EPA: February 28, 2014

EPA Action: Approved, December 9, 2016, 81 FR 89008

Docket Link: EPA–R06–OAR–2012–0812

  • Certification Letter
  • Checklist
  • Public Notice
  • Hearing Record: Notice of Hearing Cancellation
  • Comments: none received
2010 Primary SO2

Date Sent to EPA: February 10, 2015

EPA Action: Approved, December 9, 2016, 81 FR 89008

Docket Link: EPA–R06–OAR–2012–0812

  • Certification Letter
  • Checklist
  • Public Notice
  • Hearing Record: Notice of Hearing Cancellation
  • Comments and Exhibits (Response to Comments)
2008 Primary and Secondary Lead (Pb)

Date Sent to EPA: October 5, 2012

EPA Action: Approved, December 9, 2016, 81 FR 89008

Docket Link: EPA–R06–OAR–2012–0812

  • Certification Letter
  • Checklist
  • Public Notice
  • Hearing Record: Notice of Hearing Cancellation
  • Comments: none received

The Carbon Monoxide (CO) standards have not changed since 1971, before EPA began requiring formal I-SIP submittals.