Coronavirus shutdown means fewer cars on the road across NC. Will better air quality follow?
As coronavirus has closed many businesses and grounded flights, traffic on highways and rural roads has plummeted, leaving transportation experts and environmental advocates wondering what North Carolina will look like in recovery.
According to the N.C. Department of Transportation, the number of cars on roads with stoplights and signal systems is down 31% in Charlotte, compared to just before the coronavirus closures took place.
Those drops are even greater elsewhere in North Carolina.
In Cary and Raleigh — where NCDOT State Traffic Engineer Kevin Lacy suspects there are more people who are able to work remotely — road traffic is down 50% and 43%, respectively. Road traffic in Concord, Greensboro and Wilmington is down 35%, 27% and 26%.
Since traffic from cars, trucks and other vehicles contributes toward a good share of air pollution — around 40%, according to Mecklenburg County — Lacy said he expects an improvement to air quality.
“I think it’s going to be obvious. … It’s pretty much a direct relationship,” he said.
Additionally, with fewer people on the roads, people’s driving times have shrunk, Lacy said, so cars idle less, use gas more efficiently and pollute less, he said.
Traffic has plummeted on the busiest sections of the highways — such as Interstate 77 near Charlotte or Interstate 40 near Raleigh and Durham — according to data from NCDOT. During the first week of March, those sections of the highway saw around 100,000 drivers a day. Recently, there are fewer than 60,000 a day.
The number of people on other roads — everything from state and local roads to less trafficked sections of highways — has also decreased significantly.
On less busy sections of highways — such as the section of Interstate 77 north of Statesville — daily weekday volume has decreased around 40%, Lacy said.
However, the number of cars on state and local roads has dropped the most — more than 50% — from around 15,000 drivers a day before coronavirus-related closures to just over 6,000 a day last week.
Activity to businesses, stores and workplaces is also down in the county, according to recently released mobility reports by Google.
The reports come from “aggregated, anonymized sets of data from users who have turned on the Location History setting, which is off by default,” the company said. People with location history turned on can also choose to turn it off and delete data directly from their account.
The information is a sample, according to Google, and “may or may not represent the exact behavior of a wider population.”
According to the reports, visits related to workplace, retail, recreation and transit locations have declined compared to the first five weeks of 2020.
As of April 11, bus and train station visits decreased 68%, visits to places such as restaurants, shopping centers, museums and libraries decreased 52% and visits to “places of work” decreased 43%. Visits to grocery stores and parks also decreased, but by only 9% and 17% respectively. Only the residential category increased by 15% in Mecklenburg County.
The county trends roughly reflect changes in activity across the state.
Is air quality better?
Cities across the U.S. are reporting that air quality has improved from the traffic reduction, but the jury is still out on how much that trend will hold for Mecklenburg County.
In the region between Washington, D.C., and Boston, NASA estimated that nitrogen dioxide levels fell around 30%. Air quality has also improved in Los Angeles, according to reporting by Cal Matters.
Mecklenburg County’s Air Quality division said they are waiting for the coronavirus pandemic to abate before doing a robust analysis.
In the meantime, there’s some preliminary evidence that air quality has improved modestly but less so than in more industrial cities, said Calvin Cupini, who manages the citizen science program at Clean Air Carolina.
“What we’re finding is that especially during weekdays, our sensors closest to the highways are not as high during rush hour times,” he said.
Clean Air Carolina manages a little over a dozen of low-cost sensors in Charlotte to monitor air quality at the neighborhood level. The sensors, Cupini said, are an additional source of information to the state’s particle pollution monitors.
The change — 10% or less, Cupini estimated — is not that dramatic because Charlotte’s air pollution is already low compared to other major metropolitan cities and countries such as China, where there have been more dramatic air quality improvements due to the pandemic.
According to Mecklenburg County Air Quality, around 40% of nitrogen oxide emissions comes from vehicles on roads. The rest of the emissions come from a mix of sources including planes, industrial facilities and vehicles such as construction equipment.
“I wish this wasn’t happening,” said Terry Lansdell, director of BikeWalk N.C., an advocacy group. The improvement to air quality is “not a silver lining issue” when lives are being lost and shutdowns have disrupted business, he said.
However, Lansdell said he is hoping to focus on how transportation choices might change in the recovery: “Will we have business as usual? Will we have a different philosophy about how we get around and have a better understanding of the impacts of our daily transportation choices?”
Cupini emphasized that air pollution has health impacts outside a pandemic and that early research shows that exposure to fine particulate matter is associated with higher death rates from COVID-19.
In the immediate recovery, Lacy doesn’t expect commuter traffic to diminish. But now that companies have gotten a taste for remote work, he said, perhaps there will be fewer people on the roads in the long-run
This story was originally published April 22, 2020 at 7:15 AM.
