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High school science project reiterates what experts have been telling us for years

Pandemic offers detailed look at how fewer cars has helped Utah’s air

SHARE High school science project reiterates what experts have been telling us for years

Lighter-than-normal traffic is pictured on I-15 in Salt Lake City during the coronavirus pandemic on Monday, April 13, 2020.

Scott G Winterton, Deseret News

A high school student who tackled a science project for both his academic requirements and on behalf of Envision Utah is reiterating a message air quality regulators have been telling us for years: Turn off the ignition and leave your vehicle in the garage.

Caleb Grow’s study looked at traffic patterns in Salt Lake City for a year in 2020 amid the coronavirus pandemic and found that a 40% reduction in vehicles on the road led to dramatic declines in nitrogen dioxide, a group of gasses that are a precursor to the formation of PM2.5, or fine particulate pollution.

Ozone, the summertime pollution culprit, also was reduced, with Grow theorizing that a 10% to 15% reduction in driving over the course of the hottest time of year led to significant declines in that pollutant that leads to unhealthy smog.

Grow is on the youth council of Envision Utah and examined traffic patterns when Utah and other states were suddenly thrust into a dramatic lockdown to prevent the spread of the novel coronavirus.


Caleb Grow

Envision Utah


The lockdowns gave researchers a unique, real-time opportunity to examine the link between vehicles and poor air quality in the Salt Lake Valley. The shutdown’s 40% reduction in cars on the road correlated with a decrease of 25% in nitrogen dioxide in the air. Nitrogen dioxide helps drive both winter and summer pollution that leads to adverse health effects, especially with sensitive populations suffering from respiratory problems.

Regulators with the Utah Division of Air Quality have already mapped tailpipe exhaust’s contribution to poor air quality, blaming it for roughly half the fine particulate pollution that haunts the area during the winter.

Poor air quality is a recurring issue for Utah’s elected leaders as they fund research to provide more definitive pollution-tackling tools and ways to educate the public on its harmful effects.

Grow’s paper points out that regulators have tried to fight the pollution problem through emission standards, new rules and regulations and aggressive public information campaigns encouraging people to take transit, telecommute, combine trips or to carpool.

The state has also seen the introduction of cleaner burning Tier 3 fuel being produced at local refineries, which in new model cars can provide up to an 85% reduction in tailpipe exhaust — the equivalent of taking four out of every five cars off the road.

But COVID-19 and its correlating lockdowns spread the message of how fewer cars on the road improves our health in a way no one could have anticipated, and the results of this research and other bodies of study will inform pollution-cutting campaigns for years to come.

“In the past, scientists have only been able to estimate the effects that a reduction in driving would have on air pollution,” Grow writes. “The COVID-19 pandemic and subsequent lockdown provide a unique opportunity to study how air quality was actually affected by a temporary traffic reduction of up to 40%.”

Grow notes that his analysis is not the first to probe the effects of COVID-19 on air quality. A previous study from the University of Utah looked at hour-by-hour pollution levels for the specific period of March 15-31, 2020, seeing the decreases in nitrogen oxide, nitrogen dioxide and PM2.5 pollutants.

A team of researchers in China concluded there was a statistically significant link between the COVID-19 lockdown, including restrictions on traffic, and a decrease in air pollution levels, which helped form the methodology Grow says he used in his study.

Lawmakers are already taking notice of how lessons learned from the pandemic might shape the future of workplace habits and correspondingly deliver impacts that help clean up the Wasatch Front’s air pollution problem.

In this legislative session, Sen. Daniel McKay, R-Riverton, plans to push SB15, which encourages state agencies to meet a goal of 40% of employees teleworking on certain bad air days or even as high as 70% if pollution conditions are really bad.

The measure comes with reporting requirements from state agencies related to how many of its employees are able to telework under those conditions and builds on a pilot program on telework the state instituted a few years ago.