SC NOx Rules: EPA Half-Approves the Haze
Published Date: 8/19/2026
Proposed Rule
Summary
The U.S. Environmental Protection Agency (EPA or Agency) is proposing to partially approve and partially conditionally approve changes to South Carolina's State Implementation Plan (SIP) to revise source testing requirements and regulations prescribing control requirements for certain stationary sources of nitrogen oxides (NO<INF>X</INF>) submitted by the State of South Carolina, through the South Carolina Department of Environmental Services (SC DES), on October 1, 2007; July 27, 2016; September 5, 2017; April 24, 2020; and February 4, 2022. This action is being proposed pursuant to the Clean Air Act (CAA or Act).
Analyzed Economic Effects
3 provisions identified: 1 benefits, 2 costs, 0 mixed.
Moved Sources Treated as New Affected Sources
The State clarified that any existing source moved from in- or out-of-state into a permitted in-state facility after June 25, 2004, is considered a "new affected source." New affected sources are subject to the emission limits and control requirements in Section III of Standard No. 5.2.
Conditional Approval of Monitoring and MRR Rules
The EPA is proposing to conditionally approve parts of Standard No. 5.2 Section IV (monitoring, recordkeeping, and reporting for new affected sources), including specific paragraphs such as IV(A)(1)(a)-(d), IV(A)(2)(a)-(c), IV(C)(1)(a)-(d), and parts of IV(D). South Carolina committed in a May 13, 2026 letter to adopt corrective enforceable changes no later than one year after the EPA's conditional approval, as allowed under CAA section 110(k)(4).
Expanded Exemption for Emergency Generators
If you own or operate emergency power generators in South Carolina, the State's rule exempts generators that are 150 kW or smaller. The rule also exempts generators larger than 150 kW that are designated for emergency use only and that operate 500 hours per year or less for testing and maintenance.
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Key Dates
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Previous / Next Documents
Previous: 2026-16930, Air Plan Approval; South Carolina; Minor Source Permit Program Revisions
The U.S. Environmental Protection Agency (EPA or Agency) is proposing action on changes to South Carolina's State Implementation Plan (SIP) to revise regulations prescribing minor source permitting program requirements, including minor new source review (NSR) requirements, involving, in part, minor source permitting public participation, in SIP revisions submitted by the State of South Carolina through the South Carolina Department of Health and Environmental Control (SC DHEC) on October 1, 2007; July 18, 2011; August 8, 2014; July 27, 2016; and April 24, 2020. This proposal supplements previous proposals the EPA published on August 17, 2017, and January 21, 2025. This proposal is being issued pursuant to the Clean Air Act (CAA or Act).
Next: 2026-16937, Air Plan Approval; South Carolina; Minor Source Permit Program Revisions
The U.S. Environmental Protection Agency (EPA or Agency) is proposing to approve changes to South Carolina's State Implementation Plan (SIP) to revise regulations prescribing minor source permit program requirements, including minor new source review (NSR) requirements, in SIP revisions submitted by the State of South Carolina on October 1, 2007, July 18, 2011, August 8, 2014, April 24, 2020, and July 23, 2025. This action is being proposed pursuant to the Clean Air Act (CAA or Act).