• CAA requires the EPA to examine requirements of the federally enforceable SIPs in each state every three years.
• The EPA will impose a federal implementation plan whenever it finds a state plan to be inadequate or if the state is not able to create its own plan.

The Clean Air Act (CAA) requires the Environmental Protection Agency (EPA) to examine the requirements of the federally enforceable State Implementation Plans (SIPs) in each state every three years, and to make its findings available to the public. SIPs are a state’s plan for attaining and/or maintaining the primary and secondary national ambient air quality standards (NAAQS). They are developed through a public process, formally adopted by the state, and submitted by a governor’s designee to the EPA.

The elements of SIPs include:

• 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 the NAAQS.

The regulatory requirements for preparing, adopting, and submitting SIPs and SIP revisions are found in 40 CFR Part 51, and the EPA’s action on each state’s SIP is listed at 40 CFR Part 52.

The EPA will impose a federal implementation plan whenever it finds a state plan to be inadequate or if the state is not able to create its own plan.

In addition to addressing NAAQS, states in nonattainment areas must include a New Source Review (NSR) permitting program. States that are in attainment must submit Prevention of Significant Deterioration (PSD) permitting programs.

Most SIPs are available for viewing on state websites. They can also be accessed by searching the state name in the Federal Register archives.