The U.S. Environmental Protection Agency (EPA) develops National Ambient Air Quality Standards (NAAQS) to protect human health and the environment. DAQ is required to develop long-term planning documents such as State Implementation Plans (SIPs) to demonstrate how the NAAQS will be achieved, maintained, and enforced. After an area reaches attainment, a Redesignation Request and Maintenance Plan is developed to demonstrate maintenance for at least the next 10-year period. These SIPs and Maintenance Plans become the Clark County portion of the Nevada SIP. DAQ also develops Transportation Conformity Plans, in collaboration with the Regional Transportation Commission of Southern Nevada (RTC), the MPO for Clark County, to address transportation conformity issues in Southern Nevada.

Currently, the Las Vegas Valley (Hydrographic Area 212) is classified as moderate nonattainment for the 2015 Ozone (O₃) NAAQS. Hydrographic Area 212 is an attainment area subject to a maintenance plan for the CO and PM₁₀ NAAQS. Hydrographic Areas 164A, 164B, 165, 166, 167, 212, 213, 214, 216, 217, and 218 (excluding the Moapa River Indian Reservation and the Fort Mohave Indian Reservation) are attainment areas subject to a maintenance plan for the 1997 O₃ NAAQS. Click here for a map detailing Clark County's area designations.

The Las Vegas Valley (HA 212) within Clark County is a maintenance area for PM₁₀. DAQ submitted a Redesignation Request and Maintenance Plan in August 2012. On October 6, 2014, EPA approved our request and designated Clark County as an attainment area, effective November 5, 2014.

DAQ submitted a SIP in 2001, which explains how the area will attain the NAAQS for PM₁₀.  The plan is the cumulative program of all pollution control strategies, control measures, emission inventories, attainment demonstration, and state statute and local rules implemented. Final EPA approval of the plan was effective July, 2004.

Subsequently, DAQ submitted a Milestone Achievement Report (MAR) in June 2007. The MAR documents Clark County’s attainment of the 24-hour PM₁₀ NAAQS. On August 3, 2010, EPA made the determination that the Las Vegas Valley was in attainment with the PM₁₀ NAAQS (75 FR 45485), and the area was redesignated to attainment with the approval of the maintenance plan and designation request in October 2014.

The Las Vegas Valley (HA 212) within Clark County is a maintenance area for CO.  DAQ submitted a Redesignation Request and Maintenance Plan in 2008. On September 27, 2010, EPA approved our request and designated Clark County as an attainment area, effective September 27, 2010 (75 FR 59090).

DAQ submitted a SIP in 2000, describing the control measures and technologies to bring the Las Vegas Valley into compliance with the CO NAAQS. This plan was approved by EPA, effective October 21, 2004 (69 FR 56351). On June 1, 2005, EPA issued a determination of attainment for the Las Vegas Valley CO nonattainment area (70 FR 31353). A revision of the SIP was submitted in 2005 to update the CO emissions budgets using the latest model approved by EPA for transportation conformity determinations (MOBILE6). This revision was approved by EPA on August 7, 2006 (71 FR 44587).   

In September 2016, Clark County submitted its Area Designation Recommendations for the 2015 O₃ NAAQS recommending portions of the County be designated nonattainment. On December 20, 2017, EPA issued its 120-day 2015 O₃ designations letter identifying portions of the County that would be designated nonattainment. Based on the availability of more recent monitoring data, on February 23, 2018, Clark County/NDEP revised its recommendation and submitted a response to EPA's proposed designations requesting that only the Las Vegas Valley (HA 212) be designated nonattainment.  

On June 4, 2018, EPA designated the Las Vegas Valley (HA 212) as a marginal nonattainment area for the 2015 O₃ NAAQS, effective August 3, 2018 (83 FR 25776). On January 5, 2023, EPA issued its final rule determining that the Las Vegas Valley failed to attain the 2015 O₃ NAAQS by the applicable marginal nonattainment date and reclassifying the area as a moderate nonattainment area (88 FR 775).

In November 2024, DAQ submitted an attainment SIP to address the planning requirements for areas classified as moderate nonattainment and resolve EPA's finding of failure to submit. The SIP includes the following elements: emission inventories, an attainment demonstration, nonattainment new source review, a 15% rate of progress, reasonably available control measures (RACM), reasonably available control technology (RACT), motor vehicle inspection and maintenance, contingency measures, and a motor vehicle emissions budget to ensure transportation conformity.

On May 21, 2012, EPA designated Clark County as attainment/unclassifiable for the 2008 O₃ NAAQS, effective July 20, 2012 (77 FR 30088).

On June 12, 2013, DAQ enrolled in EPA's O₃ Advance program, a collaborative effort between EPA and air agencies aimed at preserving air quality in ozone attainment areas. Participating agencies work with EPA to identify, evaluate, and implement measures and programs to reduce ozone and continue making improvements in air quality. Progress reports detailing program activities, achievements, and identifying future program goals are submitted on an annual basis.

An O₃ Early Progress Plan that provides the basis for establishing early transportation conformity budgets for the Clark County 8-hour O₃ nonattainment area was submitted to EPA in 2008, and approved in 2009. A Redesignation Request and Maintenance Plan for the 1997 8-hour O₃ NAAQS was submitted in April 2011. On January 8, 2013, EPA approved our request and the Clark County nonattainment area was redesignated to attainment for the 1997 8-hour O₃ NAAQS, effective February 7, 2013.   

The Federal Clean Air Act requires States to prepare Infrastructure SIPs (I-SIP) any time EPA promulgates a new or revises an existing NAAQS and is required whether or not an area is in compliance with a new standard. In accordance with this requirement, Clark County prepares its portion of the I-SIP to demonstrate it has the programs in place to implement, maintain, and enforce the NAAQS. These I-SIPs become part of the Nevada I-SIP. The I-SIP addresses the following air quality program elements: permitting; air quality modeling; enforcement; ambient air monitoring; and, confirmation of adequate personnel, resources, and legal authorities.  

The Sulfur Dioxide (SO₂) NAAQS was revised in 2010 and the I-SIP was submitted to NDEP in May 2013 for inclusion as a revision to the Nevada SIP.

The Ozone (O₃) NAAQS was revised in 2008 and the I-SIP was submitted to NDEP in February 2013 for inclusion as a revision to the NV SIP. The O₃ NAAQS was revised in 2015 and the I-SIP was submitted to NDEP in September 2018 for inclusion as a revision to the Nevada SIP.

The Nitrogen Dioxide (NO₂) NAAQS was revised in 2010 and the I-SIP was submitted to NDEP in December 2012 for inclusion as a revision to the Nevada SIP. 

The Lead (Pb) NAAQS was revised in 2008 and the I-SIP was submitted to NDEP in July 2012 for inclusion as a revision to the Nevada SIP. 

In 2008, the Nevada Department of Environmental Protection (NDEP) submitted a consolidated I-SIP for the 1997 8-hour O₃ NAAQS, and the 1997 and 2006 NAAQS for PM_2.5. This was a joint effort between NDEP, Washoe County Health District, and DAQ.  EPA published a proposed rule for approval of the I-SIP on August 3, 2012. The final rule was promulgated on October 23, 2012.

The Transportation Conformity Plan details consultation criteria, policies, and procedures that applicable local, state and federal agencies must follow when addressing transportation conformity issues within Clark County. DAQ updated the plan in 2008. In July 2008, EPA issued a finding that the Transportation Conformity Plan fulfilled the requirements in 40 CFR Part 51, Appendix V. Subsequently, EPA issued a direct final rule in November 2008.