While Utah has made strides reducing particulate matter pollution over the Wasatch Front in recent years, local emissions reductions have had little impact on ozone levels, a less visible form of air pollution plaguing Salt Lake City and surrounding cities.
Ozone is a colorless gas that irritates sensitive lung tissues when inhaled, leaving scarring and potentially permanent damage. This pollutant can trigger coughing and shortness of breath, and lead to asthma and chronic obstructive pulmonary disease, or COPD, and other diseases.
In Salt Lake City, the ozone problem is so persistent, the U.S. Environmental Protection Agency (EPA) is about to reclassify the city’s non-attainment status to the federal ozone standard from “marginal” to “moderate,” a move that would kick in mandatory emission reductions and planning for the northern half of the Wasatch Front.
Now Utah’s elected leaders and regulators are asking the EPA to hold off because, they contend, some of Utah’s ozone concentrations—as much as 10%—can be traced to emissions emanating 7,000 miles away in Asia.
Over the last 15 years, the Wasatch Front air has seen a 40% reduction in volatile organic compounds and nitrogen oxygen emissions—the “precursors” that lead to both fine particulate, or PM2.5, and ozone pollution, according to Utah Gov. Spencer Cox. Yet despite this achievement, high levels of ozone remain unchanged over this time period, he wrote in a May 24 letter, signed by three other top elected leaders, to EPA’s acting regional administrator Debra Thomas.
Supported by a 198-page “demonstration,” the leaders say Utah’s ozone mostly comes from sources the state Division of Air Quality has no control over, such as nearby wildfires and Chinese power plants. Acknowledging that their current studies lack sufficient rigor, they are asking the EPA to give them a chance to prove it.
A higher ozone non-attainment classification would “likely result in lasting consequences for the state’s economy with negligible impacts on ozone pollution,” the letter states. “This, of course, is a lose-lose situation of the highest order for Utah and must be avoided.”
But environmentalists say Utah’s case that its ozone pollution comes from abroad is weak and speculative — and beside the point. In a rebuttal, they insisted state officials holster their request for special consideration from EPA and strengthen controls on local emission sources.
“If all cities and states, such as Los Angeles, blamed their emissions problems on international sources and the difficulty of reducing ozone concentrations, as Utah is attempting with its Demonstration, there would be no steps taken – including by states whose pollution impacts Utah – to reduce pollution,” said Joro Walker, staff attorney with Western Resource Advocates. “Millions more Americans would suffer the health consequences.”
Ozone pollution forms in the atmosphere in a photochemical reaction that combines “precursor” emissions into unstable three-atom oxygen molecules that have a corrosive effect on plants, automobile tires, human organs, almost anything they come in contact with. Salt Lake City’s ozone levels spike in the summer when ample sunlight accelerates these reactions. In numerous instances, these levels exceed the federal standard, set at 70 parts per billion, or ppb, averaged over an 8-hour period.
An area is considered out of attainment if its fourth highest annual concentration exceeds 70 ppb averaged over three years.
Children are especially at risk because repeated ozone exposure inflicts a cumulative effect. Those who train and recreate outdoors are also at risk due to an increased chance of ozone exposure on warm, sunny days.
In 2018, the EPA designated the northern Wasatch Front airshed, comprised of Salt Lake and Davis counties and parts of Tooele and Weber counties, as “marginal” non-attainment in regards to the federal 8-hour ozone standard. (The southern portion of Utah’s main population center remains in compliance.)
The designation triggered an Aug. 3, 2021, deadline for achieving attainment, which clearly won’t happen. Monitoring data over the past three years shows no progress toward reducing ozone levels, which is expected to result in a non-attainment reclassification that could complicate the state’s plans to develop a busy logistics hub in Salt Lake City.
Such a classification would require the state to develop a plan to get Salt Lake City’s air into compliance as quickly as possible, reduce precursor emissions by 15% over six years, identify contingency measures, and require “reasonably” available control technologies. Fitting Utah’s proposed Inland Port into such a regulatory mix would not be easy and would give opponents another bureaucratic cudgel in their fight against the port.
Over the past three years, monitoring stations at Rose Park and Bountiful, two of the closest to the port site, recorded the airshed’s worst ozone levels. Rose Park violated the 8-hour standard 19 times in 2018 and 13 times in 2020. In those years, Rose Park’s fourth highest reading was 80 parts per billion—10 points over the limit.
Salt Lake City’s ozone levels tend to spike in early evening on calm, clear summer days, then subside over night. Recently these levels have edged toward the unhealthy range on nearly a daily basis. On June 17, for example, ozone peaked at 77 ppb at 7 p.m, according to DAQ monitoring data. The 8-hour peak that day was 72, slightly above the federal standard.
Also that day, monitoring stations in sparsely populated towns in southern Utah recorded ozone peaks just a few points lower, according to Bryce Bird, the Division of Air Quality’s director.
To him, those high values seen in Escalante and other towns provided circumstantial evidence that ozone levels in Utah and elsewhere in the Interior West stem from sources blown in from elsewhere.
Regardless, Bird’s agency is preparing for the more onerous ozone classification and is looking for ways to cut emissions as the law requires.
“We are seeing high ozone earlier [in the year] than we have in the past. With the high temperatures, we’ve had ozone exceedances over the past couple weeks, even today,” Bird said Tuesday. “Clearly we have an ozone problem in the state. We are certainly not claiming otherwise.”
Under the Clean Air Act, a non-attainment area may avoid reclassification if regulators can demonstrate that the area would have met the ozone standard, “but for” the influence of pollution from international sources, according to Bird. Utah’s request for such consideration is the first from a non-border state.
Utah’s case is based on three technical analyses, two by the state and third by the environmental consultant Ramboll at the direction of the Utah Petroleum Association (UPA) and Utah Mining Association.
At a recent Air Quality Board meeting, UPA president Rikki Hrenko-Browning said requirements imposed under a stiffer ozone designation will do little to lower ozone concentrations in Salt Lake City, while possibly impeding efforts to better understand Utah’s ozone situation.
“A further complication is that local and state emissions contribute to only a very small part of ozone along the Wasatch Front,” Hrenko-Browning said. “Studies by EPA and others show that for the northern Wasatch Front, only 20% or less of the local ozone comes from in-state manmade emissions, the rest comes from international or natural sources.”
In other words, there is very little a federally-mandated emissions-reduction program would accomplished.
That’s just bad policy, according to Walker.
“We can control local emissions and people’s health, particularly the young and the elderly in our family friendly state, are at stake. Obviously, we should be doing everything we can to reduce air pollution along the northern Wasatch Front. I would argue it’s immoral not to address local pollution sources,” she said. “Ozone concentrations along the northern Wasatch Front could be incredibly harmful and dangerous and bad for the economy.”