Reducing pollution can have positive impacts in unexpected places.
Air pollution has reached endemic proportions across much of the planet and it’s not just people who suffer from it. Animals do too.
It follows that cleaning up the air benefits not only people but animals as well and this is exactly what a team of researchers at Cornell University and the University of Oregon has found.
Better air quality that has followed in the wake of a federal program in the United States aimed at reducing ozone pollution, they explain in a new study, may have saved up to 1.5 billion birds in the past four decades, or a fifth of the country’s entire avian population.
Ozone is produced in large quantities by power plants, cars and other human activities. In the upper atmosphere the gas forms a protective layer that shields the biosphere from the sun’s ultraviolet rays. At ground level, however, ozone is a pollutant, which is a major component in smog.
Ozone pollution in cities can have a harmful effect on human health, which has long been known, and the team of scientists in the U.S. set out to see if there has been a relationship between air pollution and the abundance of birds by help of models that combined bird observations with ground-level pollution data and existing regulations.
In the process, they tracked monthly changes in bird abundance, air quality, and regulation status across more than 3,200 counties over a period of 15 years while focusing on the NOx Budget Trading Program, a cap-and-trade federal project whose aim has been to reduce emissions of ozone precursors from large industrial sources such as power plants.
The results indicate that ozone pollution is especially harmful to small migratory birds, such as sparrows, warblers, and finches, which make up 86% of all North American bird species on land. It harms birds by damaging their respiratory system, and it also affects them by harming their food sources.
“Not only can ozone cause direct physical damage to birds, but it also can compromise plant health and reduce numbers of the insects that birds consume,” says Prof. Amanda Rodewald, director of the Center for Avian Population Studies at the Cornell Lab of Ornithology.
“Not surprisingly, birds that cannot access high-quality habitat or food resources are less likely to survive or reproduce successfully,” Rodewald says. “The good news here is that environmental policies intended to protect human health return important benefits for birds too.”
Without air-quality regulations and ozone-reduction efforts of the Clean Air Act, up to 1.5 billion birds could have died over the past few decades, the scientists say.
“Reducing pollution has positive impacts in unexpected places and provides an additional policy lever for conservation efforts,” observes Ivan Rudik, a professor at Cornell’s Dyson School of Applied Economics and Management.