Scientists are examining whether the unique shifts in air pollution during the coronavirus pandemic could validate or challenge the public science used to regulate vehicle emissions.
A team of institutions led by George Washington University thinks the variability among those shifts could reveal a more accurate picture on how much cars and trucks pollute, and eventually influence emissions rulemaking.
Most emission tests are done in laboratories. Regulators then use that data to estimate how much nitric oxide and nitrogen dioxide, for example, are released into the atmosphere by vehicle type, said Dan Goldberg, research scientist at George Washington.
“This is giving us a real-world example of how we can test it,” Goldberg said in an interview.
The research focuses on the significant variability in pollution levels around the world during the pandemic, as seen from satellites. That could be due to differences in which emissions sources have been most affected by economic shutdowns.
To get a more precise reading, researchers will examine pollution levels near U.S. highways, and compare that with high-resolution data on traffic changes over the same period, Goldberg said.
Scientists in Canada and the U.S. have noticed a 30% drop on average in nitrogen dioxide in major cities, while passenger vehicle use has fallen roughly 50% in most U.S. cities in recent months, he said.
The research is backed by a one-year grant from NASA.
Any impact on policy is at least at least two to three years away, Goldberg said. But key industry players are skeptical that data gathered during the pandemic will one day influence policy.
One program Goldberg said could be affected is the EPA’s nitric oxide and nitrogen dioxide limits for heavy-duty trucks, which are currently being updated for models in 2025 and beyond.
There is appetite among industry for more real-world testing because engines are tested in laboratories separate from the actual vehicle, said Allen Schaeffer, executive director of the Diesel Technology Forum, which represents truck and carmakers that use diesel engines.
But data drawn from the atmosphere now is “a snapshot in time” that would only reveal what happens under the pandemic’s unique conditions, and shouldn’t influence air quality policy, he said.
Many variables also need to be controlled, including the role of reduced congestion, less truck idling, and shorter wait times at international borders, said Glen Kedzie, vice president of energy and environmental counsel at American Trucking Associations, an industry group.
Any solid model for estimates needs a combination of lab tests and real-world measurements, Kedzie added in the interview.
Greater Falls in China, Italy
The team will look at similar data from China and Italy, and then try to determine if specific policies or technologies, like filters on diesel engines, may be responsible for some of the differences in pollution, Ray Minjares, program director at the International Council on Clean Transportation, a partner group, said in an interview.
Chinese and Italian cities have shown a greater decrease in nitrogen dioxide than cities in the U.S.
In Canada, pandemic data could one day change short-term air quality forecasts and improve policy proposals, like those touting zero-emission vehicles as beneficial to human health, Mike Moran, research scientist at Environment and Climate Change Canada, another partner group, said in an interview.
The U.S. Environmental Protection Agency is independently collecting air quality data during the pandemic. But a comprehensive and systematic analysis needs to take place before it would update any models or draw any conclusions, a spokesperson said on background on Friday.
“In time, however, data, analysis, and research on this period will be vetted and folded into” the agency’s processes, which inform its policies and regulations, the spokesperson wrote in an email.
Minjares, from the International Council on Clean Transportation, noted that a link between pollution and traffic variations may not be found. Or the changes in atmospheric chemistry could be due to something else in the end, like naturally occurring changes in the weather, he said.
If fruitful, atmospheric research today could also improve modeling for a range of industries, including coal power plants, since their estimates are based on the same information and approaches as those for vehicles, said Vijay Limaye, a former EPA scientist and climate change and science fellow at the Natural Resources Defense Council, a nonprofit environmental advocacy group.
“When you can subtract part of the contributions from transportation, you’re better able to isolate the contributions from other sectors,” Limaye said.