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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. This is primarily due to newer vehicles that emit substantially lower pollution 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 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. The level of pollution from particulate matter, 2.5 microns in diameter or less (PM2.5), is a significant concern. Fortunately, PM2.5 emissions from transportation sources are projected to decline by 52% from 2008 through 2019, due to improvements in auto technology, increased transit utilization, and other travel choices. Despite this progress, there is still more that we can and should do.

As we work now 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 SIP, a plan for reducing and controlling emissions in the state to meet National Ambient Air Quality Standards (NAAQS). The 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 year 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 improvement 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 SIP for each regulated pollutant and each designated air quality non-attainment or maintenance area. 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), Salt Lake City and Ogden City (carbon monoxide or CO), 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

Ogden CityMaintenance AreaCarbon Monoxide (CO)
Moderate Non-Attainment AreaParticulate Matter (PM10)
Salt Lake CityMaintenance AreaCarbon Monoxide (CO)
Salt Lake CountyModerate Non-Attainment 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 other counties as PM2.5 non-attainment areas. With support from WFRC, the Utah Division of Air Quality (DAQ) has worked to develop a new section of the 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 aid in the emission reduction effort by reducing pollution from traffic congestion and improving transit service.

In June of 2005, the original one-hour ozone standard was revoked and the EPA established a new eight-hour ozone standard. Salt Lake and Davis counties are in attainment for the 2005 eight-hour standard. Therefore, the original SIP for these areas has been replaced by a plan to maintain ozone related emissions at or below 2005 levels, in an effort to comply with the new standard.

A new ozone standard of 70 ppb was approved in October of 2015. Areas of non-attainment for the new ozone standard were due to be designated by EPA in October of 2017. Any designated non-attainment areas will be required to demonstrate conformity for ozone precursor emissions beginning 12 months after the official EPA designation.

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