When EPA establishes a new or revised National Ambient Air Quality Standard (NAAQS) under Clean Air Act (CAA) sections 108 and 109, all states are required to develop and submit to EPA a plan that provides for the implementation, maintenance, and enforcement of the new or revised air quality standard. This type of submission is referred to as an infrastructure state implementation plan, or I-SIP.
These plans have several required parts to them that are commonly referred to as “I-SIP elements.” An I-SIP submission meets these required elements by demonstrating that the state laws, rules, governmental structure, and other resources—or the “infrastructure” of the state—are sufficient to implement, maintain, and enforce the air quality standards statewide.
I-SIP elements include provisions for:
- Authority to implement control measures
- Ambient air quality monitoring
- Prevention of emissions transport outside the state
- Source monitoring
- Emergency power
- Visibility protection
- Air quality modeling
- SIP revisions