China's International Air Pollution
Is the United States Part of the Problem?

by Stevan Harrell
April 28, 2014

This essay by Stevan Harrell, Professor of Anthropology, Professor of Environmental and Forest Sciences, and Adjunct Professor of Chinese at the University of Washington, is part of the roundtable “China’s Air Pollution Problems.”

China’s air pollution is a horror story that has captivated readers and viewers around the world. Many observers have pointed out that it is a major contributor to pollution in Japan and Korea, and even blows across the Pacific to affect air quality up and down the coast of North America. A recent study estimated that on the worst days, Chinese emissions accounted for 12%-24% of the sulfate, 2%-5% of the ozone, 4%-6% of the carbon monoxide, and up to 11% of the black carbon particulate over the West Coast of United States. [1]

But there is another side to the story. Some of that pollution is caused by emissions from the factories that produce goods for the United States and other foreign markets. Given that about 24% of China’s GDP consists of manufacturing for export, and that the United States accounts for about 20% of China’s total exports, then around 5% of China’s GDP comes from goods manufactured for the U.S. market. We must also keep in mind, that manufacturing generates more emissions than do other sectors of the economy, such as agriculture and services. Thus, perhaps 6% or 7% of China’s air pollution is attributable to the U.S. export market. In other words, the percentage of China’s pollution attributable to trade with the United States is about the same as the percentage of pollution in the Western regions of the United States attributable to China on a bad day. But remember that we are only talking about the West Coast and that pollution levels in California, Oregon, and Washington are much lower than those in the highly populated areas of China. The Chinese, in other words, are getting the worse end of the deal.

Part of the reason behind China’s pollution is that the energy intensity of the Chinese economy—the amount of energy that it takes to produce a certain volume or value of goods—is still very high compared with that of the United States and other wealthy countries. Estimates vary widely, but according to the International Energy Agency, China’s energy intensity per dollar value is about 58% higher than the United States. [2] Although exports to the United States account for 3%-7% of China’s emissions of various pollutants, if those products had been produced in the United States, they would have added only 1%-2% to U.S. pollutant emissions. The U.S. economy is more energy efficient, because it depends less on coal and includes more stringent emissions controls. [3]

Because over 60% of China’s energy is produced by burning coal, which produces more pollutants than other forms of energy generation, when we talk about the energy intensity of the Chinese economy, we are primarily talking about its coal intensity. Coupled with less stringent emission controls, China’s economy simply generates a lot more pollution for the buck than does the U.S. economy. But in fact, this coal intensity is not primarily due to manufacturing, much less to export manufacturing. About 52% of the coal burnt in China goes to power generation—some of it for industry to be sure, but large amounts also for residential and commercial heating. In the biggest cities, for example, several times as much coal is burned in the wintertime as in the summer, indicating that heating accounts for the great majority of coal consumption. [4]

It is not surprising that manufacturing is not the primary source of air pollution. In Los Angeles in the 1950s, when cars were the main cause of pollution, going downtown meant stinging eyes and a scratchy throat. Although the levels of particulate matter in Los Angeles at that time were below those experienced in China’s recent severe pollution episodes, they were still well above current world standards. And ozone, the main component of Los Angeles’s famous smog, was several as times as high as levels recently measured in Beijing. [5] Now no one would say that Los Angeles’s air is wondrously clean, but it no longer hurts the eyes or the throat even on the worst days, and measured pollutant levels have in fact fallen dramatically. This bodes well for China’s cities in the long run as China continues to decrease the energy intensity of its economy, switch to alternative sources, and install pollution-control equipment. But it will be a while before we see dramatic improvements.

Meanwhile, China has recently embarked on a massive effort to move coal-derived pollution away from the cities, in addition to replacing coal with clean energy sources. The government has announced the construction of sixteen coal bases near their largest coalfields in Shanxi and Inner Mongolia. Large quantities of coal will be gasified and transported by pipeline to the major cities, where it will burn much cleaner and cause less smog than if it had been burned as coal. [6] Yet while this policy may bring relief to the cities, it shifts the burden of pollution onto the poorer people living in the coalfield areas, who are fewer in number and less powerful politically.

Already people living near one of the first coal bases are complaining of respiratory diseases. In addition, the total greenhouse gases emitted by coal gasification plus combustion of the gas to generate energy are approximately twice the amount that would be released if the coal were burned directly. In other words, we are trading air pollution for global warming, which is hardly the kind of trade most of us would want to make.

Further, more coal than ever is coming out of the Powder River Basin in Wyoming and other rich coal seams of North America; the United States is estimated to have a 200-250 year supply of coal reserves. [7] Since the United States is burning less coal and China’s demand seems to be growing, there have been plans to build coal terminals near Bellingham and Longview, Washington, to ship a projected 108 million tons of coal per year to China, beginning in the 2020s.

But the trajectory of China’s economy counsels caution. As recently as summer 2012, well after China’s recovery from the effects of the world financial crisis, China experienced a coal glut. Warehouses were full and ships importing coal were waiting offshore to unload, and the government took advantage of the glut to shut down some of the smallest and most dangerous mines. The glut is over for now, but it may well have signaled a leveling off of China’s coal demand as China moves aggressively to increase the amounts of power generated from alternative energy sources. In fact, economic projections forecast that China’s coal consumption will peak before 2020 and decrease fairly rapidly after that.[8] This not only contributes to medium-term optimism about air pollution but also calls into question the idea that the proposed Pacific Northwest coal terminals will ever be profitable. Given that coal transport to the terminals by train brings the risk of increased air pollution near the railroad routes, massive traffic congestion at railroad crossings between Wyoming and the Pacific Ocean, and coal spills at the ports, it seems wise to scrap the coal terminals and help China ameliorate its air pollution problems. [9]


[1] Jintai Lin et al., “China’s International Trade and Air Pollution in the United States,” PNAS, February 4, 2014, 1736-41.

[2] “International Energy Agency, Key World Energy Statistics 2013,

[3] Lin et al., “China’s International Trade and Air Pollution in the United States.”

[4] Mei Zheng et al., “Seasonal Trends in PM2.5 Source Contributions in Beijing, China,” Atmospheric Environment 39, no. 22 (2005): 3967–76.

[5] Lauren B. Hitchcock and Helen G. Marcus, “Some Scientific Aspects of the Urban Air Pollution Problem,” Scientific Monthly 81, no. 1 (1955): 10-21.

[6] William J. Kelly, “China’s Plan to Clean Up Air in Cities Will Doom the Climate, Scientists Say,” InsideCimate News, February 13, 2014,

[7] U.S. Energy Information Administration, “Coal Explained: How Much Coal Is Left?” May 28, 2013,

[8] “The Unimaginable: Peak Coal in China,” Citi Research, September 4, 2013,

[9] Eric de Place, “Running ‘Off the Rails’: ForestEthics’ New Report on the Northwest Fossil Fuel Blow-Up,” Sightline Daily, March 13, 2014,

This is one of three essays in the roundtable “China’s Air Pollution Problems.”

1. China’s International Air Pollution: Is the United States Part of the Problem?

    By Stevan Harrell

2. Addressing the Gap between Rhetoric and Reality in China’s Air Pollution Control:

    Why Civil Society Is Essential

    By Isabel Hilton

3. Hydropower as an Alternative Energy Source in China: Costs and Benefits

    By Bryan Tilt

Stevan Harrell is Professor of Anthropology, Professor of Environmental and Forest Sciences, and Adjunct Professor of Chinese at the University of Washington.

This roundtable was organized by Claire Topal, Senior Advisor for International Health at NBR, for the Center for Health and Aging.