Improved air quality and reduced ozone pollution that followed the 1970 passage of the U.S. Clean Air Act and later amendments have saved the lives of 1.5 billion birds across the continent, according to a team of researchers that includes the University of Oregon’s Eric Zou.
The research, Zou said, shows that pollution regulations that are nominally designed to protect human health can provide value for other species as well.
The study published online ahead of print Nov. 24 in the Proceedings of the National Academy of Sciences. Zou, now with the UO Department of Economics and National Bureau of Economic Research, worked with Cornell University colleagues as a postdoctoral researcher in the project.
“Our paper takes a first stab at this possibility by looking at the effect of a pollution regulation on birds, one of the only species whose presence and abundance have been measured systematically in the past several decades,” Zou said. “We found evidence that the regulation-induced pollution reduction has provided substantial benefits to birds abundance.”
Such benefits of environmental regulation have likely been underestimated, said the study’s lead author, Ivan Rudik, of Cornell’s Dyson School of Applied Economics and Management. Reducing pollution, such as ozone, can have positive impacts in unexpected places and provide an incentive for conservation efforts, he said.
Ozone is a gas that can be good or bad. It occurs in nature and is also produced by power plants and cars. A layer of ozone in the upper atmosphere protects the Earth from the sun’s harmful ultraviolet rays, but ground-level ozone is hazardous and a primary pollutant in smog.
To explore connections between bird abundance and air pollution, the research team used models that combined bird observations from the Cornell Lab of Ornithology’s eBird program with ground-level pollution data and existing regulations.
Zou, an environmental economist, said he was asked to join the team to help in the study’s design and statistical analyses because of expertise in using economic tools to study environmental topics.
The researchers tracked monthly changes in bird abundance, air quality and regulation status for 3,214 U.S. counties over a span of 15 years. They focused on the NOx Budget Trading Program, which was created in 2003 to reduce the regional transport of nitric oxide emissions from power plants and other large combustion sources in the Eastern U.S.
The study’s findings suggest that ozone pollution is most detrimental to small migratory land birds such as sparrows, warblers and finches, which make up 86 percent of all North American species. Ozone pollution directly harms birds by damaging their respiratory system and indirectly affects birds by harming their food sources.
Last year, a separate study published in Science by the Cornell Lab of Ornithology showed that North American bird populations declined by nearly 3 billion birds since 1970. The impacts of the Clean Air Act, as found in the new study, protected bird populations from even greater losses.
Zou, who joined the UO last year as an assistant professor, was drawn to the project, he said, by its interdisciplinary approach.
“Economists these days study a wide variety of topics, and there is a branch known as environmental economics that looks at the interaction between the environment and human society,” he said. “Economists care about the cost and benefits of policies, and we’ll go extra miles to study the unknowns of these policies.”
The data and evidence found in the new study, he said, point to a co-benefit for other species from a policy that had been designed to benefit humans with cleaner air.
Earlier this year, Zou and colleagues from Harvard University and the University of Illinois at Urbana-Champaign, where he had earned his doctorate, confirmed that hospital visits, especially by older people with respiratory illnesses, rose on the eve of thunderstorms. That study appeared in the journal JAMA Internal Medicine.