An analysis of data from a 2017 study of winter air over Salt Lake County reportedly shows that up to 25% of the Wasatch Front’s winter air pollution during inversion may be indirectly due to emissions from the US Magnesium in Tooele County.
US Magnesium officials have refuted the study’s methodology and findings.
The study was printed in February in the Journal of Environmental Science and Technology. The lead author was Carrie Womack, a research scientist with CIRES — Cooperative Institute for Research in Environmental Studies, a joint effort between the National Oceanic and Atmospheric Administration and the University of Colorado Boulder.
Womack testified in support of House Bill 220, Emission Reduction Amendments, sponsored by Rep. Andrew Stoddard, R-Sandy, during the state Legislature’s 2023 General Session.
The original version of HB 220 appeared to target US Magnesium with a requirement to measure bromine point sources in Tooele and Box Elder counties to establish a baseline and then require a 50% reduction in bromine emissions by December 2030.
Bromine is a halogen, which is emitted by the US Magnesium along with chlorine. Bromine, however, is not classified by the U.S. Environmental Agency as a pollutant.
The air around US Magnesium was reported by the study to contain 3 parts per billion of bromine but nobody could answer Rep. Tom Jimenez’s, R-Tooele, question about what level of concentration is acceptable.
The EPA and the state do not regulate bromine emissions. They do not require reporting of hormone emissions nor have they set a maximum level for bromine emissions or determined an acceptable level of bromine concentration in air.
The NOAA inspired study does not claim that bromine itself is a pollutant or part of the fine particulate matter — PM 2.5 — that is trapped by winter inversions that is said to cause health related problems.
Scientific modeling completed as part of the study showed that bromine speeds up the conversion of nitrous oxides, volatile organic compounds and ammonia in the air to ammonium nitrate, which is a major secondary pollutant contributing to PM 2.5 air pollution — especially during winter inversions.
“Modeling demonstrated that the chlorine and bromine emitted by the refinery were responsible for 10 – 25% of regional PM 2.5 during winter pollution episodes,” read a summary of the study on NOAA’s website.
Tom Tripp, former Tooele County Commissioner and technical services director for U.S. Magnesium, told the Transcript Bulletin that the study, based upon a few days of data from almost six years ago, is not accurate.
“The amount of bromine that the study says that U.S. Magnesium releases is more bromine than U.S. Magnesium has onsite or brings in and there isn’t enough bromine in the lake to account for the difference.”
Bromine exists in the Great Salt at a ratio of 1,000 parts of chlorine to 1 part bromine, according to a response to a question during a Utah House committee meeting.
Tripp also points out that due to technical reasons, U.S. Magnesium has been shut down and has not produced magnesium for six months.
“You would think if U.S. Magnesium is responsible for 25% of the air pollution on the Wasatch Front after being shut down for six months, you would see a significant improvement in air quality,” Tripp said. “But the EPA’s own data shows no significant improvement.”
EPA’s data for the PM 2.5 Air Quality Index for Salt Lake County is an indicator of how PM 2.5 concentration affects air quality.
An index of 100 marks the end of “moderate” air quality where the EPA starts to recommend groups of people sensitive to PM 2.5 start to take action.
Comparing Jan. 1, 2023 through March 12, 2023 to the same time period in 2022, the median PM 2.5 Air Quality Index for 2023 was 10 points lower than in 2022.
Out of the 71 days in the 2022 to 2023 comparison, the PM 2.5 AQI was lower in 2023 than in 2022 for 43 days and higher for 28 days.
Womack told a legislative committee that comparing one year’s data to another year’s data may not be accurate due to other environmental influences such as weather and inversions.
HB 220, as finally passed by the Legislature, requires that the state Department of Environmental Quality conduct an air emissions inventory of point sources of halogen emissions in Box Elder, Davis, Salt Lake, Tooele, Utah and Weber counties. It also requires the DEQ to recommend a state standard for halogen emissions and develop a plan for emission reduction to be implemented by December 2026.
“This will allow us to get ahead of the EPA and start to regulate emissions and improve our air quality,” Stoddard said.