Montana State Implementation Plans (SIPs)

Although the 1990 Clean Air Act (Act) is a federal law covering the entire nation, state and local air pollution control agencies (Agency) do much of the work to fulfill the requirements of the Act. For example, an Agency would hold a local hearing on a permit application by a power or chemical plant or take the lead in assessing a penalty to a company for violating an air pollution standard. Additionally, an Agency would develop community air pollution control programs to address automobile emissions, outdoor burning, road dust, or similar sources of air pollution.

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Under the Act, the U.S. Environmental Protection Agency (EPA) sets Standards for air pollutants. These Standards ensure that all Americans have the same basic level of health and environmental protection. EPA makes regulations to control sources of air pollution. The Act allows Agencies to adopt and enforce more protective air pollution regulations than EPA. However, Agencies are not allowed to have weaker air pollution regulations than those established by EPA.

Because air pollution control problems often require special understanding of such factors as local industries, geography, housing patterns, and economic constraints, Agencies are better suited to regulate sources of air pollution than EPA. The Act recognizes this fact and confers upon Agencies the primary responsibility for assuring that air pollution never exceeds the Standards.

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Agencies develop and maintain air pollution control plans frequently referred to as State Implementation Plans, or 'SIPs'. These control plans explain how an Agency will protect against air pollution under the Act. When referring to a state's SIP in general, it is defined as the collection of programs, policies and rules that Agencies use to attain and maintain the primary and secondary National Ambient Air Quality Standards (Standards). EPA must approve each SIP, and if a SIP fails in some way to protect the Standards, EPA may reject an Agency's SIP and assume administration of any specific portion of the Act in that state and/or develop its own implementation plan for the state.