A recent study has shown that US factories in China are churning out smog that is making its way over to the west coast of the United States, writes Conor de Paor

For more than 30 years the US has been outsourcing many of its manufacturing lines to China and studies have shown that despite this move in production, global winds have been bringing Chinese factories’ air pollution right back over to the US.

Chinese production costs are a fraction of their American equivalent. What has literally gone up in smoke, however, is the notion that harmful pollution would be removed from the US to the other side of the Pacific.

Much of China’s energy is generated by coal-burning power stations. The by-product of burning coal is the formation of a smoky fog, or smog. Smog is a cloud of soot, sulphur dioxide and many other components. The volumes being produced are such that in 2013, the north-eastern city of Harbin in China was so smothered in smog, that roads, schools, and the airport had to close as a result.

Jinai Lin, a professor of Beijing’s Peking University, and his colleagues have been studying these Chinese emissions. They looked at emissions generated in China for the production of goods consumed there and for goods that were exported to the US.

The team’s study was the first to quantify the effect of Chinese emissions on the US. It focuses on data obtained in 2006 and by using various complex computer simulations they have determined that between 17 – 36% of Chinese smog comes from factories that are producing goods for export. One fifth of these goods are manufactured for the US market.

Combined with atmospheric modelling, the team have realised that trans-Pacific winds, also known as westerlies, bring this smog to the west coast of the US over cities such as Los Angeles and Seattle. According to the study, it takes around six days for the pollutants to reach American soil, often arriving before the exported goods which caused them.

On a daily basis during 2006 it was found that up to a quarter of sulphate pollution over the western United States originated in factories in China that were manufacturing goods for export. Particulate matter, of which sulphate is a major constituent, is quite hazardous to human health and can easily cause respiratory disease and lung cancer.

The team draws the conclusion 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 US actually surpassed China in emissions in 2008 according to a study by the Carnegie Institute of Science in Stanford, California. In the study, emissions associated with goods produced in China for the American market are tallied in America’s overall carbon footprint.

This is called Consumption Based Accounting and it has been argued that consumers should bear some of the responsibility for environmental damage associated with goods that have been manufactured for them abroad. However, the UN and the Kyoto Protocol look at emissions from a Production Based Accounting view. This considers all emissions produced in a country to be the responsibility of that country alone.

“We’ve outsourced our manufacturing and much of our pollution, but some of it is blowing back across the Pacific to haunt us,” said Steve Davis, a University of California at Irvine scientist and a co-author of the study. “Given the complaints about how Chinese pollution is corrupting other countries’ air, this paper shows that there may be plenty of blame to go around.”