As the pandemic shut down factories and offices across the country, and more people worked from home, air quality experts kept a close eye on environmental impacts. Did the changes make a difference?

Yes and no. Local officials with the Missouri Department of Natural Resources, the Mid-America Regional Council and other groups that regularly monitor the region’s air quality have been tracking changes before, during and after the pandemic. 

Although some air quality metrics saw a momentary improvement during last spring’s shutdowns, the effects were short-lived. The more noteworthy change to air quality in recent years instead seems to be the gradual decrease in levels of pollutants like nitrous oxide, ozone and particulate matter (PM2.5) pollution.

Here’s a breakdown.

How did shutdown affect car emissions?

The Missouri Department of Natural Resources reported last October that levels of nitrogen dioxide, a pollutant formed in the atmosphere from the nitric  oxide found in vehicle exhaust and industrial emissions, took a dip during last year’s stay-at-home orders from March 24 to May 4 when compared to the same period in 2019. 

By June and July, though, nitric oxide and nitrogen dioxide levels (collectively, NOx) were closer to normal — especially on weekdays, when people were likely returning to work. 

“I think it’s hard to say we’re back to normal per se since the pandemic’s such an interesting situation,” said Stephen Hall, air quality analysis section chief with the Missouri Department of Natural Resources. “It’s going to take some time to really understand how emissions are going to trend over time as a result of this.”

Daily traffic on Interstate 70 in Kansas City, Missouri, near Blue Ridge air monitoring site, 2020 during COVID-19 pandemic shutdowns. Traffic had nearly returned to previous-year levels by June. (Credit: Missouri Department of Natural Resources)

Good news about Kansas City’s ozone levels

Another pollutant on experts’ radar is ozone. It’s not directly emitted by polluters, but its precursors, nitrogen dioxide and volatile organic compounds, are. When they’re exposed to sunlight, the two compounds undergo a reaction to form molecules of ozone. 

Although it is the same molecule that forms the ozone layer in the stratosphere that protects us from the sun’s harmful ultraviolet rays, down here in the troposphere, ozone — the main component of smog — is harmful to human health. People most at risk from ozone exposure include young children, the elderly, people with asthma and people who work outside for prolonged periods. It’s primarily harmful to throat and lung tissues.

The Environmental Protection Agency strengthened national ozone standards in 2008 and again in 2015. The Kansas City area has met the current standards since 2019. A few areas near St. Louis have been having more trouble, but the Missouri Department of Natural Resources reports that preliminary data suggests they’ll meet their goals starting this year as well.

Maximum monitor design values for ozone, 1999-2000, Kansas City area (Credit: The Mid-America Regional Council). Compliance with ozone quality standards is measured with an index called a design value, which is the three-year average of the fourth-highest ozone reading from that year (in parts per billion).

Ozone levels have been steadily declining in the Kansas City area for the past few decades. 

“We weren’t keeping up with the ozone standards back in the ’90s, but for the last 20 years we’ve been under a maintenance plan to get back in attainment,” said Karen Clawson, air quality program manager with the Mid-America Regional Council. “We’re starting to see our ozone levels decrease over time.”

Clawson said the primary reason for this decline is that a few power plants in the area have been decommissioned. But it’s also been helpful that vehicles have become more fuel efficient, and Evergy has “invested quite a bit in renewable energy,” Clawson said. 

As for any changes during shutdowns, Clawson said, “we could see a little bit of a drop compared to normal, but there’s just so many other influencing variables that it’s hard to tease out what’s really going on.”

Beware of particle pollution from fires, dust storms

Another major air quality issue is particulate pollution, which experts classify into two major groups based on their particle size: PM2.5 and PM10. 

The former, the smaller of the two, has been gaining attention as more comes to light about its detrimental health effects. A 2020 study published in the journal Science Advances found that tightening PM2.5 standards in the U.S. to meet the World Health Organization’s recommendations would save over 143,000 lives in a decade. Luckily, PM2.5 levels have been on the decline nationally since 2000. PM2.5 pollution comes from a wide variety of sources, from construction sites to smokestacks to fires.

These particles are particularly harmful to humans because they’re small enough to get into the bloodstream. In addition to potential respiratory effects, exposure to this type of pollution can cause heart problems including premature death in people with heart disease. Recent evidence also suggests exposure to particulate pollution increases mortality from COVID-19.

In 2020, the Kansas City area had three PM2.5 events, Clawson said — days when PM2.5 levels were high enough to be considered harmful. The first occurred after the prescribed burns in the Flint Hills in Kansas. Management with fire is a critical component to some ecosystems like prairies, though the smoke can be an irritant. 

The managers in that area coordinate to reduce adverse impacts of burning and to address the public health impact. 

“The (land managers) need to be able to burn, and it’s good for the ecosystem, but it’s also bad for public health. So it’s a balance,” Clawson said. “They’ve done a really good job of balancing that, I think.”

The second PM2.5 event was caused by a giant cloud of dust that blew from the Sahara Desert; the third was smoke from Fourth of July fireworks

Though these events are often detectable by community members, it’s important to remember that not all pollution is so overt.

“Most folks will think about air quality when they see or smell something going on in the environment,” Hall said. “But the interesting thing about certain air pollutants is that there are some, such as carbon monoxide, that are colorless and odorless. … (That’s why) we should always be monitoring air quality conditions to make sure we’re all doing what we need to do to improve air quality in our state and local areas.”

Multiple sources like the EPA, state-level Department of Natural Resources, local meteorologists and groups like the Mid-America Regional Council work in tandem to issue alerts to the community when air pollution levels are dangerously high. Many sources will communicate a daily air quality index, rating the day’s air on a scale from healthy (green), through moderate (yellow and orange) to the most unhealthy (red). 

Different organizations use different scales and may focus on different pollutants, but the general idea is the same: On a high-alert day, people should stay home and stay inside if possible to reduce their exposure — especially those at high risk, like people with asthma. Multiple sources are available online to check current air quality levels, like the Missouri DNR, AirNow, the Mid-America Regional Council’s AirQKC and many weather apps.

Overall, Clawson said, Kansas City has fairly decent air. 

“Our air quality has gotten a lot better. It can always be improved, just like other areas of the country,” she said. “But it’s a good place to live, here, definitely.”

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Anna Funk is a freelance writer and editor based in Kansas City. After earning a Ph.D. in plant biology, she started her journalism career as a AAAS Mass Media fellow at the Milwaukee Journal Sentinel,...