Utah’s air pollution mitigation efforts may be making wintertime smog worse

A new study conducted by researchers at the University of Utah, in collaboration with the University of Colorado Boulder and NOAA, has found that efforts to limit emissions of nitrogen oxides from cars and power plants may in fact be contributing to heightened wintertime air pollution. The research is contrary to what was previously understood by experts, and could outline new guidelines for better mitigating winter cool air inversions.

Ammonium nitrate aerosol pollution, NH4NO3, often comprises a sizable portion of total particulate matter (PM) in the air, particularly in winter months.

By analyzing pollution measurements in Salt Lake Valley, Utah - an area which commonly experiences high particulate counts in the winter - researchers of a recent field campaign were able to discover that controlling Nitrogen Oxide, a precursor to NH4NO3, was not effective at reducing overall NH4NO3 levels in the Valley. Contrarily, the initial control of volatile organic compounds (VOCs), which is neither a precursor to nitrate or ammonium, was effective in mitigating NH4NO3 levels, as a result of effecting the chemical’s oxidation cycles.

These findings later led researchers to discover that the “total add oxygen” chemical process that creates summertime ozone, also creates wintertime NH4NO3. As a result, it's thought that more effective measures of mitigating ozone will also reduce the effects of winter cool air inversions.

According to the research press release, an approved expansion of the study will apply the same research methods across the entire U.S. West, offering new strategies for tackling wintertime pollution.