China’s export industry is responsible for dirty emissions that are blowing across the Pacific Ocean and contributing to smog in the United States, a new scientific study says.
About one-fifth of the pollution China spews into the atmosphere comes from producing goods for export to the United States and other countries, according to the paper by a group of scientists that was published Monday in the Proceedings of the National Academy of Sciences. Winds blow pollutants from Chinese power plants and factories across the Pacific in about six days, where they boost levels of smog in the United States.
Los Angeles and parts of the eastern U.S. experienced at least one extra day of smog that exceeded federal health standards for ozone in 2006 as a result of emissions from export manufacturing in China, the study found.
"Rising emissions produced in China are a key reason global emissions of air pollutants have remained at a high level during 2000–2009 even as emissions produced in the United States, Europe, and Japan have decreased," the scientists wrote. "Outsourcing production to China does not always relieve consumers in the United States — or, for that matter, many countries in the Northern Hemisphere — from the environmental impacts of air pollution."
Nine scientists in the United States, China and the United Kingdom used data from 2006 to quantify how much of the air pollution reaching the U.S. West Coast from China is from the production goods for export to the United States and other countries. Scientists followed the path of air pollutants, including sulfur dioxide, nitrogen oxides carbon monoxide and black carbon, through the atmosphere to gauge their effects on air quality in the United States.
While the United States has reaped some of the benefits of outsourcing -- cheaper cellphones, televisions and appliances and big declines in air pollution -- rising emissions in China have paralyzed cities there with severe smog.
The paper is a reminder that U.S. demand for cheap imports from China has a way of blowing those environmental problems back at us, said Steve Davis, an Earth system scientist at UC Irvine and co-author of the study.
"It's sort of a boomerang effect," he said.
Davis expressed hope that the findings would be used by world governments working to craft international agreements to limit emissions of carbon dioxide that are driving climate change as well as short-lived air pollutants that are responsible for poor air quality around the globe.
"We need to move beyond placing blame for who's creating these emissions and realize that we all have a common interest in reducing the pollution," Davis said.
Since the 1990s, scientists have known that pollution from China is carried across the Pacific by westerly winds and that it worsens air quality along the U.S. West Coast. Those emissions contribute only slightly to U.S. smog levels, which are overwhelmingly caused by local emissions from vehicles, factories and power plants.
“We shouldn’t take an alarmist perspective,” Davis said. “Los Angeles air quality is not going to be what it was in the 70s or 80s because of this.”