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Air Quality

Photo courtesy of the Utah Transit Authority.

Air quality along the Wasatch Front has improved markedly over the past two decades. Salt Lake City was recently designated by the Environmental Protection Agency (EPA) to be free of carbon monoxide (CO) pollution after being designated as a CO non-attainment area 42 years ago in 1978. This is primarily due to newer vehicles that substantially reduced emissions and increasing options for residents to walk, bike, or use transit. Continuing to improve air quality along the Wasatch Front, however, remains a challenge now and in the future.

Air quality is central to the Wasatch Front Regional Council’s (WFRC) work and responsibilities. WFRC considers air quality impacts when developing the Wasatch Choice 2050 (WC2050) Vision and the Regional Transportation Plan (RTP). The RTP must meet the air quality standards identified in the Utah State Implementation Plan (SIP), which implements the federal air quality standards for the State of Utah. This means that the vehicle emissions resulting from the transportation projects proposed in the RTP may not exceed the level set for them in the SIP.

Portions of the WFRC region have been designated as a non-attainment area for fine particulate matter (PM2.5) and for ozone; and Salt Lake County and Ogden City are also designated as non-attainment for coarse particulate matter (PM10). Fortunately, emissions from transportation sources are projected to decline by 52% from 2019 to 2050 due to improvements in car and truck emission technology, increased transit utilization, and other travel choices. Despite this progress, there is still more that we need to do.

As we work to provide transportation choices and plan our communities in a way that is consistent with the regional growth principles of the WC2050 Vision, our air quality will benefit from cleaner vehicles, more transit choices, shorter and fewer auto trips, and reduced congestion.

For additional information regarding air quality, please contact Kip Billings.

Air quality conformity is a federal requirement in the context of transportation plans and air quality goals. Emissions from vehicles may not exceed limits defined in the State Implementation Plan (SIP), a plan for reducing and controlling emissions in the state to meet National Ambient Air Quality Standards (NAAQS). The Regional Transportation Plan (RTP) and the Transportation Improvement Program (TIP) developed by WFRC must meet this air quality conformity requirement for all of the years defined in these plans. This means that vehicle emissions estimated for the last year of the RTP (2050) may not exceed the budget identified in the SIP. Failure to meet conformity requirements restricts spending of federal and local transportation funds to safety, maintenance, or projects on minor roads only. If conformity requirements are not met, transportation funds may not be used to add capacity to principal arterials and freeways or to expand fixed guideway transit facilities.

All current transportation plans and programs for the Wasatch Front region conform to the established SIP and its various sections. Changes will likely continue to be made to federal air quality standards, which will require corresponding changes to the SIP. The attainment (or “maintenance”) status for the Wasatch Front region may be found in the “What is a SIP?” section.

There is a separate section in the State Implementation Plan (SIP) for air quality for each regulated pollutant and each designated area of air quality non-attainment or maintenance. Within the Wasatch Front region, there are five areas that are addressed in separate sections of the SIP: Salt Lake County and Ogden City (PM10 or coarse particulate matter), Ogden City (carbon monoxide or CO), Northern Wasatch Front ozone non-attainment area (including Salt Lake and Davis Counties, as well as portions of Weber and Tooele Counties), and the Salt Lake PM2.5 non-attainment area (fine particulate matter pollution control area including Salt Lake and Davis counties, as well as portions of Weber, Box Elder, and Tooele counties).

Wasatch Front Region Non-Attainment Designations

Northern Wasatch Front (including Salt Lake and Davis Counties, as well as portions of Weber and Tooele Counties)Marginal Non-Attainment AreaOzone
Ogden CityMaintenance AreaCarbon Monoxide (CO)
Moderate Non-Attainment AreaParticulate Matter (PM10)
Salt Lake CountyMaintenance AreaParticulate Matter (PM10)
Salt Lake (including Davis and Salt Lake counties, as well as portions of Weber, Box Elder, and Tooele counties)Serious Non-Attainment AreaParticulate Matter (PM2.5)

In September of 2006, the US Environmental Protection Agency (EPA) implemented a more stringent national standard for PM2.5 of 35 μg/m3 (micrograms per cubic meter) replacing the former 65 μg/m3 standard. Effective in April of 2009, the EPA designated Weber, Davis, Salt Lake, and portions of Weber, Box Elder, and Tooele counties as a PM2.5 non-attainment area. With support from WFRC, the Utah Division of Air Quality (DAQ) has worked to develop a new section of the State Implementation Plan (SIP) to reduce PM2.5 related emissions to a level that will enable the Wasatch Front region to once again be in compliance with national PM2.5 standards. The improved vehicle emission technology and national standards enacted in 2004, 2007, and 2017 will be instrumental in the DAQ’s plan to achieve the new PM2.5 standard. WFRC’s RTP will also contribute to the emission reduction effort by reducing pollution from traffic congestion and improving transit service.

A new ozone standard of 70 ppb was approved in October of 2015 and the Northern Wasatch Front was designated by the Environmental Protection Agency (EPA) as a marginal non-attainment area for ozone in October of 2017. The Northern Wasatch Front ozone area consists of Salt Lake and Davis Counties, as well as portions of Weber and Tooele Counties. After experiencing continued levels of ozone above the 70 ppb standard in 2020, the Northern Wasatch Front is expected to be designated in 2021 by EPA as a moderate non-attainment area for ozone. With assistance from WFRC and other stakeholders, the State Division of Air Quality will be required to prepare a State Implementation Plan for ozone in the Northern Wasatch Front area, and WFRC will need to include ozone emissions in the conformity analysis of the Regional Transportation Plan and the Transportation Improvement Program.

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