Air quality as it relates to transportation is an important concern among citizens and policy makers in Utah’s metropolitan areas where population growth has placed an increased demand on our transportation system.  

A construction zone on Bangerter Highway

Utah is one of the fastest growing states in the nation.  Our transportation system will need to be made as efficient as possible to support that growth. Projects planned through year 2030 will improve mobility – will building those projects necessarily contribute to a decline in air quality?

UDOT works with other state agencies in “a continual consultation process to make sure we’re in compliance with federal air quality standards,” according to Elden Bingham, Air Quality Programs Coordinator for UDOT. Bingham participates in the compliance conformity process along with representatives from federal and state regulatory agencies and local Metropolitan Planning Organizations.

The federal government requires states to monitor and comply with National Ambient Air Quality Standards, and the Utah Division of Air Quality monitors air quality in Utah.  The EPA has designated six pollutants that are monitored by DAQ throughout the state – the pollutant of concern to transportation planners are ozone and its precursors hydrocarbons (HC) and nitrogen oxides (NOx), carbon monoxides (CO), and particulates (PM-10 or PM-2.5). These pollutants cannot exceed specified levels. When air quality does not meet federal standards, a non-attainment area can be designated. States with non-attainment areas are required to develop a Statewide Improvement Plan.

SIPs, which are approved by the federal government, must contain air quality goals and strategies to meet those goals. UDOT works with the DAQ to develop transportation strategies that meet the air quality improvement goals in the SIP. All transportation projects must conform to the SIP in order to receive federal funding.

Conformity to Utah SIP goals takes place on the regional and project level. Metropolitan Planning Agencies manage regional transportation conformity of projects on the Transportation Improvement Plan, a list of proposed projects. After modeling future traffic demand and determining the level of emissions expected to be produced, the MPOs issue an Air Quality Memorandum that confirms that the projects in the TIP won’t exceed goals of the SIP.

Project level conformity is the responsibility of sponsors, like UDOT, who build transportation projects.  Projects that receive federal funding or those that are regionally significant (including primary arterial roads, freeways or fixed guide-ways) must conform to goals in the SIP. On the project level,  sponsors conduct a Hot Spot Analysis to show that transportation projects don’t contribute adversely to the air quality in the area.

Planning studies done by the Wasatch Front Regional Council show that improved mobility can actually have a beneficial impact on local air quality. Idling and excessive stop and go traffic puts strain on automobile engines causing increased emissions. WFRC compared future transportation conditions in 2030 with and without planned projects. By eliminating traffic delay, vehicle emissions will be reduced by 285,000 vehicle hours per day – that equals 1.2 tons of the precursor pollutant nitrogen oxide.

Precursor pollutants contribute to the formation of other pollutants; nitrogen oxide produces ozone along with light and heat. Air quality standards are expected to be reconsidered in 2013.


Utah’s emissions inspection program and cleaner running cars have also helped improve air quality.

To learn more about air quality conformity, visit the Air Quality Planning page on the UDOT website.

UDOT’s TravelWise website suggests option for drivers who want to save energy and help roadways operate more efficiently.

The Hot Spot Manual gives project managers air quality analysis guidance.

WFRC has posted the 2012-2014 TIP and and Air Quality Memorandum.

The Federal Highways Administration produces a brochure that summarizes the air quality conformity process.
The Utah Division of Air Quality website shows current conditions.

The Utah Department of Environmental Quality lists tips for individuals:  What You Can Do.

Tribune story: Salt Lake City and County officials ask parents to cut back on idling.

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