What’s behind northern Utah’s ‘brown clouds’? New study pinpoints a major source

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SALT LAKE CITY — A magnesium plant near the Great Salt Lake is a major producer of chemical elements behind the “dense brown winter clouds” that sometimes hang over Salt Lake City and other parts of Utah’s northern half in winter, a new federal study finds.

The study, led by the Cooperative Institute for Research in Environmental Sciences, finds that the U.S. magnesium plant in Tooele County produced high levels of chlorine and bromine during a 2017 study. Researchers say the chemicals made a “significant contribution” to cloud formation and an increase in particulate matter levels by 10-25% in the Wasatch Front area during a winter inversion period.

“[The plant]is known to give off a lot of chlorine, but what was really interesting about this study was that we found a lot of bromine species,” said Carrie Womack, a scientist with the National Oceanic and Atmospheric Administration, the lead author of the Study said in an interview with KSL NewsRadio on Thursday.

“The interesting reason is that the (Environmental Protection Agency) requires facilities to report their chlorine emissions, but they don’t require them to report their bromine emissions,” she added. “Bromine plays a big role in this buildup of PM 2.5.”

Womack also said her team also found a “complete disappearance of all ozone” in the region, which typically occurs in Earth’s polar regions and had not previously been observed “this far south.”

Her team’s findings were published Wednesday in Environmental Science and Technology.

Understanding pollution during winter inversions

The study itself provides an analysis of plume samples collected during NOAA research flights in January and February 2017 on the Great Salt Lake.

The researchers wanted to study the area because some valleys between the mountains to the west have levels of particulate matter that exceed federal standards more often than other areas of the country. In the Salt Lake Valley, for example, there is an average of 18 days of poor air quality each year, particularly during the winter inversion period.

“Our goal was to try and understand how these emissions become particulate matter,” Womack said.

High levels of particulate matter can affect lung and heart health. A 2012 study led by the University of North Carolina’s Gillings School of Global Public Health found that there was a surge in asthma-related emergency room visits in the Salt Lake Valley during winter inversions, based on data collected from 2003 to 2007 were collected.

Womack and researchers from the University of Utah, the University of Toronto, the University of Washington and the EPA began sifting through the data and found many known sources of particulate matter: pollution from industrial, agricultural and transportation sources. All of these are important factors in the creation of pollution that have been warned about for years.

A previously unknown player

However, the US magnesium plant also stood out in the data, Womack said. The researchers flew by the facility when they flew over the Great Salt Lake on their first flight because it was already a “known source of pollutants in the area,” she said, adding that the air in the area even smelled of bleach smelled

However, the high bromine levels surprised them as they had never been reported. While state and federal agencies track chlorine and nitrogen oxide emissions, they don’t track bromine, an element found naturally in the earth’s crust and seawater that can cause health problems when transmitted in high enough doses.

The team’s modeling showed that chlorine and bromine levels, which were high near the facility, significantly increased the number of special substances in the area. Womack explained this is because the two chemicals are “very effective” at converting other pollutants into particulate matter, which local residents see in the form of “brown clouds” during an inversion.

“It surprised us how much this one facility contributed to PM 2.5, but there are many other sources in the area,” Womack said, adding that the facility may be the largest emitter of chlorine in the United States, but it’s so unclear how it ranks in bromine since this chemical isn’t tracked federally.

Researchers also noted an ozone deficiency near the plant due to the halogenated compounds. This is because sunlight activates the halogenated compounds “to become these very reactive chemical species,” Womack said.

Update pollution tracking?

It is unclear what the finding means for health. The researchers say this could be something that could be studied more in the future. They also believe further studies could be conducted to better understand the role of bromine or the magnesium plant in the region’s air quality.

Meanwhile, a spokesman for the Utah Department of Environmental Quality wrote in an email to KSL.com that the study could help the Utah Division of Air Quality improve its quality monitoring practices in the future.

“Halogen emissions such as chlorine and bromine could affect summer ozone and winter PM2.5 pollution along the northern Wasatch Front. Being able to accurately estimate chlorine and bromine emissions in northern Utah could help (the department) refine its regulatory air quality modeling and better inform policy decisions,” the agency wrote.

US Magnesium LLC did not respond to KSL’s request for comment as of press time. It is the largest magnesium producer in North America. According to the Royal Society of Chemistry, magnesium is commonly used in all sorts of products like car seats, laptops, power tools and even firecrackers.

The company also made headlines last month after the Utah Division of Water Quality rejected US Magnesium’s application for a project to continue the Great Salt Lake canal, citing “insufficient information” from the company.

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Carter Williams is an award-winning reporter covering general news, nature, history and sports for KSL.com. He previously worked for the Deseret News. He is a Utah transplant next to Rochester, New York.

Adam Klein

Adam Small is a reporter for KSL NewsRadio.