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China is the world’s largest emitter of anthropogenic air pollutants, and measurable amounts of Chinese pollution are transported via the atmosphere to other countries, including the United States. One third of China's greenhouse gases is now from export-based industries, according to Worldwatch Institute, a U.S.-based environmental research group, and coal-burning factories were the biggest sources of the air pollutants – and greenhouse gases.
Westerly winds can carry air pollution from China across the Pacific Ocean in just a few days.
A satellite image of smog over China. Westerly winds
can carry air pollution from China across the
Pacific Ocean in just a few days. A new study is
linking air pollution in the Western United States
to China’s booming exports. credit: NASA/NOAA
A study published in the
Proceedings of the National Academy of Sciences by
researchers in the United Kingdom, China and the
U.S. analyzed the impacts of trade-related Chinese
air pollutant emissions on the global atmospheric
environment, linking an economic-emission analysis
and atmospheric chemical transport modeling.
Researchers found that in 2006, 36% of anthropogenic
sulfur dioxide, 27% of nitrogen oxides, 22% of
carbon monoxide, and 17% of black carbon emitted in
China were associated with production of goods for
export.
For each of these pollutants, about 21% of
export-related Chinese emissions were attributed to
China-to-US export.
Atmospheric modeling shows that transport of the
export-related Chinese pollution contributed 3–10%
of annual mean surface sulfate concentrations and
0.5–1.5% of ozone over the western United States in
2006.
This Chinese pollution also resulted in one extra
day or more of noncompliance with the US ozone
standard in 2006 over the Los Angeles area and many
regions in the eastern United States.
On a daily basis, the export-related Chinese
pollution contributed, at a maximum, 12–24% of
sulfate concentrations over the western United
States.
As the United States outsourced manufacturing to
China, sulfate pollution in 2006 increased in the
western United States but decreased in the eastern
United States, reflecting the competing effect
between enhanced transport of Chinese pollution and
reduced US emissions. Our findings are relevant to
international efforts to reduce transboundary air
pollution.
For more information
PNAS - China’s international trade and air pollution
in the United States
(MDN)
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