The coronavirus pandemic upended commuting patterns in the Pittsburgh region. In the early months of Pennsylvania’s shutdown, traffic dropped by as much as 50 percent in Allegheny County, according to Streetlight Data. On average, PennDOT officials say vehicular traffic remains about 20 percent lower than normal.
In a recent paper, a Carnegie Mellon University research group documented a drop in air pollutants. Their work showed that less driving meant lower concentrations of emissions such as carbon monoxide and nitrogen dioxide. Professor Albert Presto said more surprising was the decrease in fine particulate matter, which are really small particles that can cause big health problems.
“That was the same whether we were in a high-traffic place or a low-traffic place,” he said.
Air pollution can be thought about in three chunks, Presto said: the first chunk is the sort of background level of pollutants that exist essentially no matter where you go. Draw closer to a city, “with a bunch of people doing stuff,” and there’s an increase in pollutants. “If I draw it like a cartoon it’s a sort of hump over the city," Presto said. The third chunk is when you move right next to a source of pollutants such as a highway or an industrial facility.
Presto said the uniform drop in fine particulate matter they measured points to the importance of improving air quality across the region: you don’t necessarily have to live next to a highway to feel the benefits of less traffic.
Presto said on one hand the paper tells the story of what happens when a lot of people can’t go to work because of a pandemic. But another way to look at is “this is what a potential future atmosphere could look like,” he said. If half of the region’s vehicles became plug-in electric cars -- setting aside for the moment how that electricity is produced -- Pittsburgh could see pollution drop.
For PennDOT, the drop in traffic provided more time to repair roads. The District 11 office, which covers Allegheny, Beaver and Lawrence counties, was able to pave Route 8 during the day, something they never would have allowed before, said executive director Cheryl Moon-Sirianni. However, the decrease in vehicle miles traveled could shrink the agency’s budget.
“That’s 20 percent less of funding we’re getting because our funding is obviously from the gas tax,” she said.
What that means for next year’s budget remains uncertain. For the moment, Moon-Sirianni’s district will temporarily delay seeking bids on $120 million worth of work for next year in order to prioritize critical work such as bridge repairs.