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Air Quality

Regulation and SIP Management

State Implementation Plan

The State Implementation Plan (SIP) is developed to show how a state will meet the National Ambient Air Quality Standards (NAAQS) for six common pollutants, called "criteria pollutants," as set forth by the Clean Air Act.

A SIP is the accumulated record of many documents that form a blueprint and timeline for the state's plans to assure compliance with the NAAQS for criteria pollutants (carbon monoxide, sulfur dioxide, ozone, nitrogen dioxide, lead, and particulate matter), as outlined in the Clean Air Act. SIPs include, among other things, control plans, regulations, inventories of emissions within the state, and transcripts of public involvement in the SIP-development process. Once approved, the SIP is enforceable by the state and EPA. Elements of South Carolina's SIP have been in place since 1972. Though there have been many amendments, there is only one South Carolina SIP. For more information, see EPA's SIP webpage.

Revising the SIP

DHEC revises the SIP for a variety of reasons, including complying with a new or revised federal regulation, to address an issue in a specific geographic area, or to address changes in state regulations that are part of the SIP.

The process for revising the SIP depends on whether or not the revision also changes DHEC regulations. If a SIP revision requires changes to DHEC regulations, then BAQ uses the process outlined on our Proposed and Recent Rulemaking page. If a SIP revision does not also change DHEC regulations, then DHEC uses the following process:

  1. Following a decision that the proposed change does not require changing State Regulations, DHEC publishes a Notice of Intent to Revise the SIP in the South Carolina State Register (Subscription required, documents also posted on our website) that describes the proposed change.
  2. The Notice of Intent to Revise the SIP starts a 30-day comment period during which members of the public may submit comments to DHEC on the proposed SIP revision.
  3. At the end of the 30-day comment period, DHEC may hold a public hearing on the proposed revisions to the SIP. The public hearing may be canceled if there are no public requests for a hearing during the 30-day comment period. At the public hearing, staff will explain the proposed revisions, answer questions, and take comments from the public. DHEC includes a record of the hearing in the SIP submittal.
  4. DHEC will consider public comments and may revise the proposed changes to the SIP. If the SIP change is not to be presented before the Board of Health and Environmental Control, DHEC then submits the final SIP document to EPA for approval
  5. DHEC then publishes a Final Notice of Intent to Revise the State Implementation Plan in the State Register.
  6. If EPA approves the SIP change, it will publish that approval in the Federal Register.
  7. If the SIP change is to be presented to the Board, DHEC staff submits the change to the Board for review. If the Board decides that more public involvement is appropriate, DHEC staff will repeat Steps 2 and 3, above. If the Board decides that more public involvement is not warranted, DHEC staff proceeds with the process at Step 5, above.

If a SIP revision does change DHEC regulations, then BAQ uses the process outlined on our Proposed and Recent Rulemaking page.


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