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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.

An area that was once designated as nonattainment, but has been redesignated as attainment, must submit a maintenance plan, as required by section 175A of the Clean Air Act. In addition, the 1997 8-hour Ozone Early Action Compact (EAC) process included maintenance provisions.

Cherokee County

On November 6, 1991, Cherokee County was designated by EPA as nonattainment for the 1979 one-hour ozone standard. On December 15, 1992, Cherokee County was redesignated as attainment for the 1979 ozone NAAQS and was required to submit a maintenance plan. On April 26, 2002, EPA approved the Revisions to the 1-Hour Ozone Maintenance SIP for Cherokee County.

On April 30, 2004, after release of the 1997 8-hour ozone NAAQS, EPA announced that Cherokee County was designated as attainment for the 1997 primary ozone NAAQS. EPA also published the final Phase 1 rule for implementation of the 8-hour ozone standard (69 FR 23951). This regulation established 110(a)(1) Maintenance Plan "anti-backsliding requirements" for areas designated attainment for the 8-hour ozone standard. These requirements mean that affected areas have to submit a ten-year maintenance plan if they were a nonattainment area, or an attainment/unclassifiable area with a section 175A maintenance plan, under the 1979 one-hour ozone standard. This requirement applied to Cherokee County.

On June 1, 2009, EPA approved the section 110(a)(1) Maintenance Plan for the 1997 8-Hour Ozone Standard for Cherokee County submitted on December 13, 2007.

York County Portion of the Metrolina Nonattainment Area

On April 30, 2004, a portion of York County, South Carolina within the Rock Hill Fort Mill Area Transportation Study (RFATS) Metropolitan Planning Organization (MPO) was designation by EPA as a moderate nonattainment area for the 1997 8-hour ozone standard as part of the Charlotte-Gastonia-Rock Hill NC-SC Nonattainment Area. On August 31, 2007, DHEC submitted its required attainment plan.

On June 1, 2011, based on air quality monitoring data from 2008 to 2010, DHEC submitted a Redesignation Demonstration and Maintenance Plan for the York County Portion of the Charlotte-Gastonia-Rock Hill NC-SC Nonattainment Area. This request also provided a maintenance plan which fulfills the requirements of Section 175A of the Clean Air Act as amended, that will ensure the area maintains the 1997 8-hour ozone standard through 2022.

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