Utah used faulty methodology to conclude I-15 expansion won’t exceed federal air quality standards, expert says

Utah says a plan to widen Interstate 15 can plow ahead because the mammoth project would not violate federal air quality standards.

Technically.

A new Utah Department of Transportation report shows the expansion would increase air pollution over the next quarter century but assumes that, as the Beehive State grows, more people will use transit and electric vehicles, keeping the anticipated pollution within the bounds of federal regulations.

An air quality advocate, however, called the study “a farce” because the analysis projected levels for only two pollutants, relied on data from a monitoring station more than 2 miles from the freeway, and included pollution data from 2020, when there was markedly less traffic on the roads.

“This is as nonsensical as trying to improve public health by handing out free cigarettes,” said Dr. Brian Moench, chair of Utah Physicians for a Healthy Environment, a group that has consistently opposed the project. “It’s just not going to help the community.”

The interstate-widening project has sparked pushback from those who say it will further gunk up the air and disproportionately affect Salt Lake City’s west side, which already suffers from poorer air quality than other neighborhoods in the Salt Lake Valley.

For its part, UDOT spokesperson John Gleason said the department “performed a thorough air quality analysis” and worked with federal experts to show the project falls within all air quality limits “set to protect public health for sensitive groups.” The agency contends that adding lanes to the road is necessary to keep up with population growth along the Wasatch Front.

Barely within bounds

UDOT is in the final stages of an environmental review of the $3.7 billion expansion project, which calls for adding a new travel lane in each direction from 400 South in Salt Lake City to Shepard Lane in Farmington.

In order to move forward, UDOT must show the plans meet federal air quality requirements.

Initially, state transportation officials argued the I-15 project did not automatically trigger an air quality analysis, but the Environmental Protection Agency required the department to complete one as a part of its final environmental impact study.

The new analysis, released this month, shows large particle pollution at nearly double UDOT’s initial estimate last fall.

[See more: Read the results from UDOT’s analysis.]

The level of small particle pollution, which the agency originally estimated would dramatically decrease, is now projected to increase by 10%, according to the new study. Small particle pollution is more dangerous and contributes to the haze experienced during Utah’s inversions.

Under the most recent analysis, UDOT projects large particle pollution barely scrapes by the federal standard for air quality.

According to the report, the level of pollution resulting from the project is actually expected to exceed federal standards, but the EPA allows UDOT to round down its findings.

Which pollutants were — and were not — studied

Salt Lake and Davis counties are already exceeding the federal limit for small particle pollution, so the feds required UDOT to study future levels.

Because of previously high levels of large particle pollution in Salt Lake County, the department also was required to model that pollutant.

Moench says the study is flawed because it fails to measure other pollutants like ozone and nitrogen oxides, which he contends would “certainly increase” if the interstate expands.

“They may have met federal requirements,” Moench said, “but as for protecting public health, that is another reason why this is a farce.”

UDOT says it did not study ozone because there isn’t an approved way to model the pollutant. The department says it was not required to analyze nitrogen oxides because Salt Lake and Davis counties are currently in compliance with air quality standards for those pollutants.

Still, Moench said, leaving ozone and nitrogen oxides out of the analysis is “a dereliction of the duty to protect public health” because those toxins could worsen the pollution levels the agency did model.

“It is another reason,” he said, “why UDOT cannot claim that this project is not a major public health mistake.”

Capturing current conditions

To create a final measure of future air quality in the study area, UDOT added the anticipated project-related pollution to current pollution levels, measured from 2020 through 2022.

In 2020, traffic dropped by 13% on state roads as the COVID-19 pandemic raged.

According to emails between UDOT environmental program manager Naomi Kisen and state Division of Air Quality technical analysis manager Christopher Pennell, the analysis used that three-year period because data for 2023 was not yet certified.

To measure the larger particle pollution, UDOT used data from a monitoring station at the former Hawthorne Elementary School on 1700 South and 700 East, more than 2.5 miles from the southernmost point of the study area at I-15 and 600 South.

“That’s going to affect the outcome of your modeling,” Moench said.

The ideal monitoring station, in Rose Park at 1400 West and Goodwin Avenue, does not collect data on large particle pollution.

Officials, meanwhile, rejected data collected from an air quality monitoring station closer to the study area, at roughly North Temple and Interstate 215, emails between Kisen and Pennell show.

Data there showed 10% more large particle pollution in the air compared to readings from the Hawthorne station. Pennell posited the higher levels were due to diesel traffic on Interstate 215 and high-wind dust events, which disproportionately affect the west side, and UDOT decided that the Hawthorne monitoring station was more representative of the freeway project area.

UDOT banking on greener future

Despite modeling that predicts there will be more cars on I-15, UDOT project manager Tiffany Pocock said that air quality won’t go over the standard and will be safe for those who live nearby.

“Vehicle emissions largely are decreasing,” Pocock said. “That is why it probably, [with] the additions to Utah’s growth in vehicles, does not exceed the air quality standards in the forecasted design year[s].”

She said that’s because there will be more low-emission vehicles on the road, cleaner fuels in use and more people commuting via FrontRunner and other modes of transportation.

Moench, however, says “overwhelming data” contradicts this, and that widening freeways induces more demand for drivers.

The added demand can also result in increased traffic congestion and emissions within as little as three years, Moench said, because there is the same kind of congestion as before — just with more cars across more lanes.

“If it does [reduce traffic], it will be kind of the first time it’s ever happened in the country,” Moench said. “You increase the attractiveness of driving a car, more people drive cars. They drive them more often. They drive them farther. … Expanding freeways spreads out development, and it increases overall commuting time and distances that people have to travel.”

Now that UDOT has found the project will conform to federal air quality standards, it can move forward.

The agency will release a full, final environmental impact statement this fall, formally moving the project into its funding, planning and construction phases. UDOT anticipates construction to be completed in 2035.

While the transportation agency says it has met federal requirements, Moench remains skeptical of its findings.

“UDOT is complying with the letter of the law but just barely,” he said. “They are certainly not complying with the spirit of the law, which is to protect public health.”

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