International trade in goods and services has a bigger impact on shifting the health burden of air pollution than atmospheric flows, a new study finds.

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International trade shifts the burden of pollution-related deaths

Environmentalists have long known that pollution wafting through the air can affect people far from the source of emissions. Now, a new study finds that international trade has likely “shifted” more than 700,000 pollution-related deaths from regions that import goods and services, like the United States and Western Europe, to those that produce them, like China. The study adds fuel to the debate over who bears responsibility for the health impacts of air pollution. 

An international team led by atmospheric chemist Qiang Zhang of Tsinghua University in Beijing looked at emissions data across 13 global regions for 2007, the last year comprehensive information was available. They concentrated on something called PM2.5, particulate matter with a diameter less than 2.5 micrometers. These fine particles, which are blamed for some 90% of premature deaths from air pollution, can lodge deep in the lungs, causing respiratory and cardiovascular diseases.

The group then integrated four different models for industrial and agricultural emissions, production and consumption patterns, the atmospheric transport of pollution, and the number of premature deaths likely caused by air pollution in different regions. Their conclusion: In 2007, PM2.5 caused 3.45 million premature deaths worldwide. About 2.52 million of those deaths were attributed to production activities like manufacturing, transportation, and agriculture. The remaining deaths resulted from windblown dust, wildfires, chemicals released by plants, and emissions from international shipping and aviation.

The researchers further found that about 12% of the premature deaths—or 411,100—resulted from air pollution that had drifted across borders. But 22% of premature deaths—or 762,400—could be blamed on emissions from producing goods and services in one region that were consumed in another. In effect, international trade shifts the human health impacts of manufacturing from countries that import goods to those that produce them, the team writes in a letter today in Nature.

“To our knowledge this is the first paper to link global supply chains explicitly to human health,” environmental economists Keiichiro Kanemoto of Shinshu University in Matsumoto, Japan, and Daniel Moran of the Norwegian University of Science and Technology in Trondheim wrote in a jointly signed email to a Science reporter.

Josep Canadell, an earth system scientist at Australia’s Commonwealth Scientific and Industrial Research Organization in Canberra, calls the study “a very significant step” in understanding the health implications of international trade.

The breakdown of regions is predictable. In terms of non–trade-related polluton, the team found that particulate matter emitted in China can be linked to more than 64,800 premature deaths in other regions, including more than 3100 in Western Europe and the United States. China’s East Asian neighbors also suffer by being downwind, with 30,900 premature deaths there traced to air pollution carried through the atmosphere. On the other hand, trade-related deaths resulted in the opposite imbalance: The consumption of Chinese-made goods in Western Europe and the United States likely caused more than 108,600 premature deaths in China.  

Zhang says they are not out to blame one region for premature deaths in another. “Our finding quantifies the extent to which air pollution is a global problem in our global economy,” he says. He adds that advanced countries need to strive for sustainable consumption and help developing countries adopt advanced pollution control technologies, whereas developing countries need to take action to reduce local emissions. “We call for international cooperation to tackle the problem,” he says.

“What we’ve done is quantify in terms of the numbers of deaths this tradeoff between economic development and environmental impact, some of which is hidden by international trade,” says Steven Davis, a co-author and earth system scientist at the University of California, Irvine. The study’s authors note one worry is that polluting industries have tended to migrate to regions with more permissive environmental regulations. “China is already strongly motivated to reduce emissions in order to improve the domestic impacts of that pollution,” Davis says. But industrialization is already moving to Vietnam, India, and Cambodia, where the commitment to pollution control isn’t as firm.

Just how international cooperation might address the issue is unclear. Canadell doesn’t see the study’s findings directly influencing climate and trade negotiations as they are now conducted. “However, it raises a significant new dimension, partially an ethical one, on the responsibilities of producers and consumers when participating in world trade,” he says. He points out that consumer pressure might have an impact on the practices of global companies, just as it did on issues like child labor and worker safety. As an example, Kanemoto and Moran point to Apple, which holds foreign subcontractors to the same labor and environmental standards that prevail in the United States. “In this way, standards flow back up through global supply chains,” they write.