BEIJING – Filthy emissions from China’s export industries are carried across the Pacific Ocean and contribute to air pollution in the western United States, according to a paper published Monday by a U.S. science journal.

The research is the first to quantify how air pollution in the United States is affected by China’s production of goods for export and by global consumer demand for those goods, the study’s authors say.

It was written by nine scholars in three nations and was published by Proceedings of the National Academy of Sciences, which last year published a paper by other researchers that found a drop in life spans in northern China because of air pollution.

The latest paper explores the environmental consequences of interconnected economies. The scientists wrote that “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.”

The movement of air pollutants associated with the production of goods in China for the U.S. market has resulted in a decline in the sulfate air quality in the western United States, the scientists wrote, though less manufacturing in the United States does mean cleaner air in the eastern United States.

Jintai Lin, lead author, said in an interview that he and the other scientists wanted to examine the transborder effects of emissions from export industries to look at how consumption contributes to global air pollution.

“We’re focusing on the trade impact,” said Lin, the Bai Ren professor in the Department of Atmospheric and Oceanic Sciences at Peking University’s School of Physics. “Trade changes the location of production and thus affects emissions.”

Powerful global winds can carry pollutants from China across the Pacific within days, leading to “dangerous spikes in contaminants,” especially during the spring, according to a news release from the University of California, Irvine, where one of the study’s co-authors, Steven J. Davis, is an earth system scientist. “Dust, ozone and carbon can accumulate in valleys and basins in California and other Western states,” the statement said.

Black carbon is a particular problem because rain does not wash it out of the atmosphere, so it persists across long distances, it said. Black carbon is linked to asthma, cancer, emphysema, and heart and lung disease.

“Los Angeles experiences at least one extra day a year of smog that exceeds federal ozone limits because of nitrogen oxides and carbon monoxide emitted by Chinese factories making goods for export,” the statement said.

Alex L. Wang, a law professor at the University of California, Los Angeles, who studies Chinese environmental policy and regulation, said after reading the new paper: “This is a reminder to us that a significant percentage of China’s emissions of traditional pollutants and greenhouse gas emissions are connected to the products we buy and use every day in the U.S.”

In recent years, scholars have been studying the impact of China’s total emissions on global air pollution and warming.

In Japan, for instance, an environmental engineer has attributed a mysterious pestilence that is killing trees on Yakushima Island to pollutants from China.