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What is a State Implementation Plan (SIP)?

What is a SIP?

The State Implementation Plan (SIP) is a plan for each State which identifies how that State will attain and/or maintain the primary and secondary National Ambient Air Quality Standards (NAAQS) set forth in section 109 of the Clean Air Act ("the Act") and 40 Code of Federal Regulations 50.4 through 50.12 and which includes federally-enforceable requirements. Each State is required to have a SIP which contains control measures and strategies which demonstrate how each area will attain and maintain the NAAQS. These plans are developed through a public process, formally adopted by the State, and submitted by the Governor's designee to EPA. The Clean Air Act requires EPA to review each plan and any plan revisions and to approve the plan or plan revisions if consistent with the Clean Air Act.

SIP requirements applicable to all areas are provided in section 110 of the Act. Part D of title I of the Act specifies additional requirements applicable to nonattainment areas. Section 110 and part D describe the elements of a SIP and include, among other things, emission inventories, a monitoring network, an air quality analysis, modeling, attainment demonstrations, enforcement mechanisms, and regulations which have been adopted by the State to attain or maintain NAAQS. EPA has adopted regulatory requirements which spell out the procedures for preparing, adopting and submitting SIPs and SIP revisions that are codified in 40 CFR part 51.

EPA's action on each State's SIP is promulgated in 40 CFR part 52 Exit EPA Click for disclaimer. The first section in the subpart in 40 CFR part 52 for each State is generally the "Identification of plan" section which provides chronological development of the State SIP.

The contents of a typical SIP fall into several categories: (1) State-adopted control measures which consists of either rules/regulations or source-specific requirements (e.g., orders and consent decrees); (2) State-submitted comprehensive air quality plans, such as attainment plans, maintenance plans rate of progress plans, and transportation control plans demonstrating how these state regulatory and source-specific controls, in conjunction with federal programs, will bring and/or keep air quality in compliance with federal air quality standards; (3) State- submitted "non-regulatory" requirements, such as emission inventories, small business compliance assistance programs; statutes demonstrating legal authority, monitoring networks, etc.); and (4) additional requirements promulgated by EPA (in the absence of a commensurate State provision) to satisfy a mandatory section 110 or part D (Clean Air Act) requirement.

Section 110(h) SIP Compilation Requirements

Section 110(h)(1) of the Clean Air Act mandates that not later than 5 years after the date of enactment of the Clean Air Act Amendments of 1990, and every three years thereafter, the Administrator shall assemble and publish a comprehensive document for each State setting forth all requirements of the applicable implementation plan for such State and shall publish notice in the Federal Register of the availability of such documents. Section 110(h) recognizes the fluidity of a given State SIP. The SIP is a living document which can be revised by the State with EPA approval as necessary to address the unique air pollution problems in the State. Therefore, EPA from time to time must take action on SIP revisions containing new and/or revised regulations and air quality plans.

In support of the Section 110(h) SIP compilation requirements, EPA now intends to publish the following SIP requirements for each EPA Region III State on EPA Region III's Air Protection Division (APD) website: (1) EPA-approved state rules, regulations and support documents such as technical memoranda associated with compliance testing; (2) EPA-approved source-specific requirements submitted by the States for inclusion into the SIP; and (3) comprehensive air quality plans, such as attainment plans, maintenance plans rate of progress plans, and transportation control plans demonstrating how these state regulatory and source-specific controls, in conjunction with federal programs, will bring and/or keep air quality in compliance with federal air quality standards. In order to best serve the public, EPA Region III intends to update the aforementioned SIP elements on the APD website every time that a revised SIP requirement becomes Federally effective.

Relationship of National Ambient Air Quality Standards (NAAQS) to SIPs

EPA has established National Ambient Air Quality Standards (NAAQS) for six criteria pollutants, which are widespread common pollutants known to be harmful to human health and welfare. The present criteria pollutants are: carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter, and sulfur oxides. See 40 CFR part 50 Exit EPA Click for disclaimer for a technical description of how the levels of these standards are measured and attained. State Implementation Plans provide for implementation, maintenance, and enforcement of the NAAQS in each state. Areas within each state that are designated nonattainment are subject to additional planning and control requirements. Accordingly, different regulations or programs in the SIP will apply to different areas. EPA lists the designation of each area at 40 CFR part 81 Exit EPA Click for disclaimer.

What Is Federally-Enforceable

Enforcement of the state regulation before and after it is incorporated into the Federally- approved SIP is primarily a state responsibility. However, after the regulation is Federally approved, EPA is authorized to take enforcement action against violators. Citizens are also offered legal recourse to address violations as described in section 304 of the Clean Air Act.

The user should be aware that the SIP-approved provisions may differ from the current State-effective air pollution control provisions for the following reasons:

  1. The State has amended its provisions, but they have not been submitted to EPA for SIP review.
  2. The State has amended its provisions, but they are currently undergoing SIP review by EPA.
  3. The SIP contains certain provisions that are no longer State-enforceable.
  4. The State provisions govern subject matter not covered by the SIP, i.e., they do not support a statutory requirement of the Clean Air Act.

However, the user should also be aware that when States have submitted their most current State regulations for inclusion into Federally-enforceable SIPs, EPA will begin its review process of submittals as soon as possible. Until EPA approves a submittal by rulemaking action, State-submitted regulations will be State-enforceable only. As EPA approves these State- submitted regulations, the regional offices will continue to update the SIP compilations to include these applicable requirements.

Glossary of Terms

State Effective Date: Describes the date that a requirement initiated by a State becomes State-enforceable.

Final FR Date: The publication date of EPA's final rulemaking notice, published in the Federal Register. EPA's approval generally becomes effective 30 to 60 days after publication.

FR Citation: References the volume (corresponding to the year of publication) and page number of the rulemaking notice in the Federal Register.

Superseded/Rescinded Date: Indicates the Federal Register publication date when a SIP requirement has been superseded or rescinded by subsequent EPA action.

Please direct questions and comments about Mid-Atlantic SIPs to Sharon McCauley at 215-814-3376 or via email at mccauley.sharon@epa.gov.


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