University of Utah researcher Daniel Mendoza and his colleagues have air quality sensors installed around Park City with the purpose of monitoring pollution during the ski season and the Sundance Film Festival. What they have discovered is that the COVID-19 pandemic also had a significant impact on the area’s air quality.

Throughout the pandemic, the air sensors watched during lockdowns as air pollution fell in residential and commercial areas, and then as pollution rose again with re-openings. The changing levels, the researchers found, which behaved differently in residential and commercial parts of the city, show where pollution is coming from and how it might change in the future under different policies.

“The lockdown period demonstrated how low pollution levels can be and showed what the background pollution is in the area,” said Mendoza, a research assistant professor in the Department of Atmospheric Sciences and visiting assistant professor in the Department of City & Metropolitan Planning. “The very low levels of PM2.5 can be considered an aspirational target and could spur increases in renewable and low-polluting energy sources.”

Before this study, neither Park City nor Summit County had any regulatory air quality sensors. Although the population of Park City is much smaller than the Salt Lake Valley, its geography still creates temperature inversions that can trap and concentrate emissions from cars, businesses and other sources. Mendoza and his colleagues set up sensors at two different locations, one atop the building of the KPCW radio station, in Park City’s “Old Town” district, representing a bustling commercial area. The other was located at the Park City Municipal Athletic & Recreation Center, in an affluent residential area.

“As we all know, COVID-19 happened and we had a natural experiment,” Mendoza said. As restrictions and precautions went into effect, the research team discovered a significant effect on the atmosphere.