University of Utah: How Air Pollution Changed During COVID-19 in Park City


July 8, 2021

Throughout the pandemic, air sensors observed during closures the decrease in air pollution in residential and commercial areas, then the rise in pollution with reopening. The changing levels, the researchers found, who behaved differently in the city’s residential and commercial areas, 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 region,” said Mendoza, assistant research professor in the Department of Atmospheric Sciences and assistant professor guest at the Department of Urban and Metropolitan Planning. “The very low levels of PM2.5 [fine particulate matter] can be seen as an ambitious goal and could stimulate an increase in renewable and low-pollution energy sources. “

The study, supported by the Park City Sustainability Office, is published in Environmental Research.

Good timing

Prior to this study, neither Park City nor Summit County, Utah had a long-term record of regulatory air quality sensors. Although Park City’s population 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, who also holds positions as adjunct adjunct professor in the pulmonary division of the Faculty of Medicine and senior scientist at the NEXUS Institute, and his colleagues installed sensors in two different locations, one at the top of the building of the KPCW radio station. , in the “Old Town” district of Park City, representing a lively commercial area. The other was located at the Park City Municipal Athletic & Recreation Center, in an affluent residential area.

“We are looking to study other areas, including the Salt Lake Valley, but we wanted to focus on Park City because of the novelty of installing sensors there,” Mendoza said. Unlike the diverse set of industrial and residential emissions in Salt Lake Valley, Park City’s emissions are primarily related to heating and road traffic. It was already a fascinating study.

“However, as we all know, COVID-19 has happened and we’ve had a natural experience,” he says. As the restrictions and precautions came into effect, the research team followed the evolution of the emissions.


Emissions declined during the lockdown period across the city, but declined more in shopping areas. Many residents have stayed at home and many offices have moved to working remotely. But the broadcasts, Mendoza says, have shifted to residential areas.

“Due to exposure issues, many people have ordered food, groceries, etc. to be delivered to their homes,” he said. “In addition, many companies allow people to work from home, at least part of the week, so car trips have shifted to residential areas instead of shopping areas.”

Studying two clearly different places in the same city is an important feature of the research, says Mendoza. “Intra-urban variability has not been studied in detail and may help us understand potential future patterns of emissions and pollution, especially as teleworking becomes a more viable and accepted option.”

The results cannot be directly extrapolated to large cities, but it stands to reason, according to Mendoza, that air pollution emissions can be similarly shifted in many cities from a central city signal to a central city signal. more dispersed residential model. “While residential areas traditionally have had cleaner air, this was not necessarily the case during and after periods of lockdown,” he said.


The sensors ensured that activity largely returned to a form of normal in May and June 2020. At the end of the study period at the end of July 2020, commercial emissions had not yet returned to prior levels. pandemic, while residential emissions had rebounded completely. The researchers noted that the emissions increased over a two-month period.

“I think it’s relatively easy to lock down a place – closed businesses and activities,” Mendoza said. “However, reopening takes a lot more time and thought.”

The researchers carefully checked their data and ruled out the possibility that the changes in emissions were due to seasonal changes or the weather. They concluded that changes in human activity produced a measurable change in air quality, a finding with far-reaching implications. Pandemic level emissions could serve as a benchmark, for example, for air pollution reduction targets. The study also showed that residential heating and cooling are important parts of the air quality equation, something to be considered by decision makers in the transition to a low carbon energy economy. .

Air pollution has improved following other events in the past, such as the Great Recession of 2008, says Tabitha Benney, associate professor of political science and co-author of the article. But these past events have not been monitored from an interurban perspective. So the trends seen in Park City, with residential shows rebounding faster than commercial shows, came as a surprise.

“However, at the county level, it appears that pollution remains low over the entire study period,” she said. “It is only when we use the interurban perspective that such patterns become apparent. It also has important implications for other urban areas.”

Find the full study here.

This press release was produced by the University of Utah. The opinions expressed here are those of the author.


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