More than half a century ago, Los Angeles began issuing regulations to decrease air pollution. On October 14, 1947, the Los Angeles County Board of Supervisors established the nation's first air pollution control program by creating the Los Angeles County Air Pollution Control District. Across the Pacific in China is known to have the distinction as the world’s larger emitter of pollutants into the atmosphere. A new study published online on January 20 in the Proceedings of the National Academy of Sciences reported that pollution from China travels in significant quantities across the Pacific Ocean to the US. On some days, pollutants from China can account for as much as a quarter of sulfate pollution in the western US. The study was conducted by researchers from China and the US, including scientists from the University of California, Irvine.
Over the last two decades, China's neighbors, such as Japan and South Korea, have regularly suffered noxious pollutants from China as environmental regulations have been sacrificed for economic and industrial growth. However, the new study notes that the United States, particularly the western United States has also been impacted. Interestingly, one reason for the Chinese import of air pollution to the US is the demand for Chinese goods imported to the United States. Cities such as Los Angeles receive at least an extra day of smog a year from nitrogen oxide and carbon monoxide from China's export-dependent factories alone. The researchers found that an analysis on US air quality revealed that Chinese air pollution related to production for exports contributes, at a maximum on a daily basis, 12–24% of sulfate pollution over the western US. They found that in 2006, 36% of sulfur dioxide, 27% of nitrogen oxides, 22% of carbon monoxide, and 17% of black carbon emitted in China were related to production of goods for export. For each of these pollutants, approximately 21% of export-related Chinese emissions were attributed to China-to-US export. Atmospheric modeling revealed that transport of the export-related Chinese pollution provided 3–10% of annual average surface sulfate concentrations and 0.5–1.5% of ozone over the western US 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 as well as many regions in the eastern United States.
The researchers are hopeful that their study will contribute to international efforts to reduce air pollution that can freely travel to other nations, some like the US, which are a significant distance from a pollution source such as China.