The Clean Air Act helps ensure that human health and the environment are protected from adverse effects of air pollution. Much of the responsibility for preventing and controlling air pollution is delegated at the state level. In order for a state to administer certain air quality programs, the state must adopt state implementation plans that limits air pollution by setting standards for six criteria pollutants and those plans must be approved at the federal level. The federal review and approval process provides for some consistency among state programs and ensures that each complies with the requirements of the Clean Air Act and federal rules.
The department's Air Pollution Control Program develops multiple plans to meet the federal standards for the following pollutants: lead, ozone, particulate matter, carbon monoxide, nitrogen dioxide and sulfur dioxide. These plans constitute one main state implementation plan (SIP). The EPA codifies all of Missouri’s federally approved SIP at 40 CFR 51.1320.
The EPA reviews pollutant standards every five years. Sometimes, a review results in a tightened standard. When this happens, the department must develop boundary area recommendations based on technical analysis of emissions and air quality information. These recommendations include the boundaries for areas that are complying with the standard (attainment), areas that are not complying with the standard (nonattainment), and areas where the analysis is unable to determine whether the area is complying with the standard or not (unclassifiable).
The tightening of criteria pollutant standard also sets off the multi-step process to develop new SIP elements. The elements required for areas that are not meeting the new standards are far more prescriptive and involved than the general SIP elements needed for areas that are already in compliance with the standard. It's not uncommon for work on the old and new standards to overlap. The department considers input from all stakeholders when developing any new or revised SIP element.
When EPA releases a new criteria pollutant standard, it triggers the need for each state to develop new SIP elements for the relevant standard. These include SIP elements that demonstrate the states authority and infrastructure necessary to enforce and protect against the new standard. These types of SIP are referred to as infrastructure SIPs and they apply statewide regardless of the designation status for areas across the state.
For any area that is designated nonattainment, the required state planning elements include many additional elements and are much more prescriptive. These SIP elements must explain the state’s emission control programs and demonstrate that those programs will bring the area into compliance with the relevant standard. Once a nonattainment area comes into compliance with the relevant standard, the state may develop a maintenance plan to demonstrate that the area will remain in compliance with the standard going forward. After a maintenance plan is approved for a nonattainment area, the area may be redesignated back to attainment for the relevant standard.
In addition to criteria pollutant SIP elements, the Clean Air Act also requires other types of state plans. Examples of these other types of plans include plans necessary to protect against visibility impairment in federal class I areas (Regional Haze) and plans to comply with federal emission guidelines for designated facilities under Clean Act Section 111(d).
The criteria pollutant pages linked below include the SIP elements associated with the relevant criteria pollutant standards. The other links provide the plan elements associated with other types of state plans.
Criteria Pollutant SIP Elements
Nonattainment Area Plans and 111(d) plans for CO2 Emissions
When EPA releases a new criteria pollutant standard, the department is responsible for developing recommendations for area boundary designations (attainment, nonattainment, and unclassifiable areas). Once the recommendations are adopted by the Missouri Air Conservation Commission, the department submits them to EPA. The recommendations are typically due within one year of the date when EPA establishes the new standard.
EPA then reviews the recommendations the department submits. If the EPA intends to make any final designations that differ from the state recommendations, then EPA will send a notice to the state 120-days prior to finalizing such designations. The state then has the opportunity to submit additional analysis to defend the state’s recommendations. EPA then finalizes the boundary designations for all areas of the country, typically within two years after EPA has established the new standard.
The map below depicts all areas of the state that are currently designated nonattainment for any of the criteria pollutant standards.
The criteria pollutant pages linked below include the files associated with the boundary designations process for the applicable pollutants.