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Air Quality

Air Pollutants - Ozone - Standards & Requirements

State Implementation Plan (SIP)

The federal Clean Air Act requires each state to develop a State Implementation Plan (SIP) that outlines the state's strategy for controlling air pollution for each of the National Ambient Air Quality Standards (standard). A SIP is a plan that can include a narrative, models, regulations, programs, and other technical documentation that a state presents as evidence of its efforts to address air pollution and maintain good air quality.

The Clean Air Act requires states to involve the general public and industry through public hearings and opportunities to comment on the development of each state plan. States then submit the initial SIP or SIP revision to EPA for approval. Once approved, the SIP is enforceable by the state and EPA.

A nonattainment plan is the specific plan designed to address a particular area in the state that has been designated as nonattainment for a standard. Once nonattainment designations take effect, the state has no more than three years to develop a nonattainment SIP revision outlining how a particular area will attain and maintain the standards by reducing air pollutant emissions in that area.

Sections 172(c), 182(a), and 182(b) of the Clean Air Act define the requirements for ozone nonattainment areas. All designated nonattainment areas must comply with the general requirements mandated by Section 172(c) of the Clean Air Act. As a Subpart 2, moderate ozone nonattainment area, the Charlotte-Gastonia-Rock Hill, North Carolina-South Carolina (Metrolina) area must also meet the additional requirements of Section 182(a) and 182(b). Elements of a nonattainment plan are based on the area's classification and can include requirements such as an attainment demonstration, reasonable further progress, and new source review.

Transportation Conformity

The Clean Air Act also requires states with areas designated as nonattainment areas for Ozone(O3), carbon monoxide (CO), particulate matter (PM10 and PM2.5), or nitrogen dioxide (NO2) to demonstrate that any transportation plans, programs, and projects planned for the area are consistent with the state's air quality goals - attaining and maintaining the standards. South Carolina incorporated a Memorandum of Agreement into the SIP to satisfy the Interagency Consultation Requirements of the Federal Transportation Conformity Rule.

For more information please contact the Bureau of Air Quality at (803) 898-4123 or by email.