When smoke wafts from coal-burning industrial regions to China's major cities, blanketing them in dense, suffocating smog, it doesn't stop there. A new study published in the Proceedings of the National Academy of Sciences found that across the Pacific, Los Angeles experiences at least one extra day a year of heavy smog attributable to Chinese factories.
China, according to the World Bank, has 16 of the 20 most polluted cities in the world -- the smog there is capable of grounding airplanes, blotting out the sun and shutting down entire cities. And air pollution in the U.S. is caused, by and large, by internal industrial activity and other local sources of fossil fuel emissions.
But according to the University of California at Irvine researchers, global winds known as "westerlies" are capable of transporting airborne chemicals, like nitrogen oxides and carbon monoxide, across the Pacific -- one some days, as much as a quarter sulfate pollution in Western states can be traced back to Chinese factories producing goods for export.
That last point is key: The study makes the crucial connection between the two nations not by demonstrating that China's pollution affects the U.S., but by showing how the U.S. is very much complicit in the pollution's formation. And, its authors claim, we get far less pollution than we deserve. From the Wall Street Journal:
Chris Nielsen, executive director of Harvard University’s China Project and an expert on air pollution in China, described the paper’s methodology as sound.
“The compelling story here is how much of China’s pollution is due to production of goods exported to the U.S., and how responsibility for China’s pollution,” is more multilateral than researchers previously understood.
The U.S., as a major buyer of Chinese-made goods, has a stake in China curbing its emissions. For each of the pollutants examined—including sulfur dioxide, nitrogen oxides, carbon monoxide, and black carbon—about 21% of export-related emissions in the year 2006 were tied to Chinese exports to the U.S, the researchers found.
Higher emissions of air pollutants from China are one reason that global air-pollutant emissions levels remain high even as such emissions have fallen from other economic powers including the European Union, Japan and the U.S.
“If all the emissions were reallocated according to where goods are consumed…emissions of many of China’s trade partners would be much higher,” they wrote. In the case of the U.S., for example, emissions of the four pollutants analyzed would have been 6-19% higher in 2006 “if the emissions embodied in its trade with China were included.”
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