3A: Progress and problems with northern Utah’s PM_2.5

Particulate matter in the air can have a noticeable impact on human health when breathed in. PM_2.5 particles are particles less than or equal to 2.5 microns (µm) that can travel deep into the respiratory system. 

The regulatory status of northern Utah counties has not changed in the past year. The Wasatch Front counties are still officially listed as “serious non-attainment,” although recent three-year
averaging periods have shown the airsheds have achieved “clean data” status. Cache County
reached “attainment” status and is listed as “maintenance” as of June 2021

For the most part, Utah’s PM_2.5 measurements indicate continued improvement of the state’s
implemented PM_2.5 reduction programs. However, some challenging inversions during
January and February 2023 resulted in several exceedances across the region (Figure 3.A.1). 

Northern Utah’s winter was characterized by frequent storms and abundant snowfall, interspersed with brief high-pressure periods that allowed for multi-day inversions. The elevated concentrations observed were also some of the highest PM_2.5 values experienced across the region within the last decade. 

Figure 3.A.2 shows that airsheds have mostly been below the NAAQs for the past three years,
suggesting that “attainment” status across the regulatory three-year averaging period can be reached.

Winter 2023 demonstrates that, although implementation protocols have resulted in recent PM_2.5 reductions, northern Utah is only a few consecutive strong winters away from once again exceeding the National Ambient Air Quality Standards