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