(CNN) -- Pollution doesn't respect national borders. Outsourcing manufacturing to China may have resulted in less pollution in some parts of the United States, but other regions have lesser air quality because of U.S.-bound Chinese products, a new study in the journal Proceedings of the National Academy of Sciences finds. "Pollution from China is having an effect in the U.S., and we need to recognize how that is affecting both our background ozone levels and also particulates that are reaching the West Coast," said study co-author Don Wuebbles, professor of atmospheric science at the University of Illinois at Urbana-Champaign. In the western United States, Chinese pollution related to exports contribute up to 12% to 24% of daily sulfate concentrations, the study said.
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Study: West Coast air quality suffers because of Chinese exports
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Manufacturing practices in China are not as efficient as in the U.S.
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Coal-burning power plants have become more common in China
The study suggests that for the United States as a whole, there's a net benefit, because the population density in the eastern United States is higher than in the @placeholder.