On December 19, 2024, the U.S. Environmental Protection Agency (EPA) reclassified the Las Vegas Valley (Hydrographic Area 212) to “serious” nonattainment under the 2015 ozone National Ambient Air Quality Standards (NAAQS). This reclassification, effective January 21, 2025, brings updated regulatory implications for stationary sources operating in the area. Facilities that emit ozone precursors including volatile organic compounds (VOCs) and nitrogen oxides (NOX) are now subject to stricter permitting requirements.
One of the outcomes of this redesignation is the requirement for major sources to complete a Reasonably Available Control Technology (RACT) review. As of early April, Clark County Department of Environment and Sustainability, Division of Air Quality (DAQ), has begun notifying owners and operators of major stationary sources of NOX and VOC in the Las Vegas Valley of their obligation to comply with these new requirements. RACT determinations are required as part of the County’s updated State Implementation Plan (SIP) to reduce ozone pollution.
The notifications, issued in early April, trigger a 120-day timeline for affected sources to submit a RACT demonstration in accordance with Section 120 of the Clark County Air Quality Regulations (CCAQRs). All required applications must be submitted within 120 days of being notified.
Regulatory Context
The new requirements stem from Section 182(b)(2) of the Clean Air Act (42 U.S.C. § 7511a), which mandates that areas designated as “serious” nonattainment for ozone must implement RACT for all major sources of NOX and VOCs, which are precursors to ground-level ozone. Clark County’s reclassification to serious nonattainment has led to the development of updated RACT rules, which are now being enforced through formal notifications to source operators.
A major stationary source is any facility with the potential to emit 50 tons or more of VOC or NOX, or 100 tons per year (tpy) or more of any other criteria pollutant, in alignment with federal nonattainment area definitions. For purposes of RACT applicability in Clark County, DAQ has set the threshold at 5 tpy per emissions unit for major sources, meaning any unit with a potential to emit at least 5 tpy of either pollutant is subject.
What Affected Sources Must Do
All owners and operators who have received a notice from DAQ must submit a major source RACT demonstration for each affected emissions unit. This must be done by applying for either a new stationary source permit or a significant permit revision under AQR Sections 12.4 or 12.5. Notably, a submission is still required even if no additional control requirements are expected to result from the analysis.
DAQ has clarified that prior RACT determinations may be accepted in lieu of a new demonstration, provided the determination was completed within the last 36 months and continues to represent current RACT. To qualify, facilities must provide a sworn certification stating that no material changes have occurred since the prior RACT analysis, specifically regarding available control technologies, technical feasibility, cost-effectiveness, and related environmental or energy impacts.
Reminder that with the lower 50 tpy NOX/VOC threshold, many sources with VOC units >5 tpy did not have to complete RACT previously as part of the moderate nonattainment RACT review. Now, any units with VOC emissions 5 tpy or greater will need to be evaluated.
Options for Sources Seeking to Avoid RACT
DAQ has also noted that facilities can avoid the requirement altogether by modifying their permits to accept
synthetic minor limits, which would be achieved by lowering their allowable emissions of NO
X and/or VOC to below the major source thresholds or lowering the allowable emissions from individually subject units to under 5 tpy. Facilities interested in this option are encouraged to reach out to
DAQ’s Permitting Section to discuss feasibility and permitting implications.
Additional resources on the RACT requirements, including guidance documents and application forms, are expected to be made available on the DAQ website in the coming weeks. Facilities are encouraged to begin reviewing their emissions inventories and preparing their permit strategies as soon as possible to avoid a last-minute rush before the upcoming deadline.
