Each state only has one SIP, which is updated through revisions that are necessary. SIP revisions are required when new state or federal regulations are enacted, when an area’s attainment status changes, or when an area fails to reach attainment. Once a SIP revision is developed and adopted by the State, it is submitted to the EPA for review and approval. These revisions often take several years to complete and are developed in close collaboration with local and federal partners and other interested stakeholders. 

Each SIP revision includes:  

• Evidence that the State has adopted the plan and that the State has the legal authority necessary to adopt and implement the plan;
• A copy of the actual regulation, or issued permit, order, or consent agreement submitted for approval and incorporation by reference into the SIP;
• Evidence that the State has followed all of the procedural requirements for the adoption/issuance of the plan including holding a public comment period and hearing and formally responding to all public comments received; 
• Identification of the pollutants, sources, and geographic area impacted by the plan; 
• Quantification of the anticipated impact on emissions from the affected sources  as a result of the control measure(s) included in the plan;
• Scientific proof (often through modeling) demonstrating that the plan is protective of the NAAQS, prevention of significant deterioration (PSD) increments, reasonable further progress (RFP), and visibility requirements, as applicable;
• Evidence that the plan contains enforceable emission limitations, work practice standards, and recordkeeping / reporting requirements, where necessary, to ensure compliance with the emission levels; and
• Special economic and technological justifications required by any applicable EPA policies, or an explanation of why such justifications are not necessary. 

Learn More

• SIP Modeling | View Modeling Page >
• Control Analysis | View Control Analysis > 

ADEQ sets and enforces state-level rules and controls pertaining to sources permitted by ADEQ. Similarly, counties with local air agencies set and enforce county-level rules and controls pertaining to sources within their jurisdiction. Additionally, local air agencies are responsible for air quality permitting within their jurisdictions.  

Local air agencies within Arizona include:

• Maricopa County Air Quality Department
• Pinal County Air Quality Control District
• Pima County Department of Environmental Quality

Once revisions to Arizona’s SIP are approved by the EPA, it is incorporated into the U.S. Code of Federal Regulations (CFR), and the requirements included in the SIP become federally enforceable. All of EPA’s regulatory actions on SIPs are published in the Federal Register. SIP revisions that have been adopted by a state are only state-enforceable until approved by the EPA. Members of the public can also file citizen suits under the CAA to address violations of SIPs and other CAA requirements.

As an individual:

• The SIP is intended to provide for the protection and enhancement of air quality to promote and protect public health and welfare. Public welfare includes protection against decreased visibility and damage to animals, aquatic life, crops vegetation, and buildings. 
• Regulations included in the SIP may impose restrictions on certain types of activities in order to be protective of the NAAQS and meet other requirements of the CAA.

As a business:

• Your business may be required to ensure that enforceable emissions limitations and other control measures, means, or techniques that are included in the SIP are in place if they are applicable to your business.

Learn More

• Arizona's SIP in the Code of Federal Regulations (CFR) | View 40 CFR Part 52 Subpart D > 

Each SIP revision, rulemaking, or permitting action must provide opportunity for the public to provide comments on the proposed action. ADEQ provides notification in the newspaper, Arizona Administrative Register, and email notification, as appropriate | Subscribe to ADEQ’s Email Notifications >

When the EPA promulgates a new or revised NAAQS, the State is required to submit an infrastructure SIP (I-SIP) revision to the EPA within three years that provides for the implementation, maintenance, and enforcement of the new or revised NAAQS | View I-SIPs > 

For each NAAQS, the EPA is required to designate all areas of each state as meeting the standard (attainment), not meeting or contributing to nearby areas not meeting the standard (nonattainment), or cannot be classified on the basis of available information (unclassifiable). This process starts with ADEQ assisting the Arizona Governor in evaluating monitoring data and other factors from all areas of the state, except for Tribal lands. Based on this information, the Arizona Governor recommends boundary designations to EPA. These recommendations assist the EPA in making the final decision regarding area designations | View Area Designations for Recent NAAQS Revisions > 

Once EPA designates an area as nonattainment, ADEQ or the local air planning agency must develop a SIP revision to reduce emissions and bring the area into attainment as soon as possible, and no later than the attainment date identified in EPA’s action. 

The SIP revision must meet the nonattainment area plan requirements in Part D of the CAA, which includes the implementation of enforceable emissions limitations and other control measures, means, or techniques necessary to ensure attainment of the NAAQS no later than the attainment date while demonstrating reasonable further progress. 

The nonattainment area plan must also include:

• An accurate emission inventory
• Certain permitting requirements for new or modified major stationary sources anywhere within the nonattainment
• Enforceable schedules for compliance
• Contingency measures for failure to meet milestones. 

After the air quality in the area improves and the area meets all of the applicable CAA requirements required for redesignation, EPA can redesignate the area from nonattainment to attainment | View Arizona’s Nonattainment Areas and Areas Redesignated to Attainment > | View eMap >  

The CAA requires each SIP to contain a New Source Review (NSR) program. NSR is an umbrella term for a program that regulates the construction of new air pollutant-emitting industrial sources or major modifications to these sources. These air quality permits are issued to sources in order to improve or maintain good air quality | View New Source Review >

The CAA also requires states to develop and implement plans to reduce air pollution that causes visibility impairment in order to restore 156 designated national parks and wilderness areas, referred to as Class I areas, to natural visibility conditions by 2064 | View Regional Haze and Visibility Progress in Arizona >

When EPA establishes emissions guidelines under Section 111(d) of the CAA, each state is required to develop a State Plan that sets standards for the existing sources in the state that are covered in EPA’s emissions guidelines. These emissions guidelines apply to specific categories of existing sources and pollutants not covered by the NAAQS | View State Plans under CAA 111(d)  >