China's high level of air pollution consisting of particulates produced by burning coal significantly shortens the lives of people exposed to it, according to a new study.

The research is based on long-term data compiled for the first time and projects that the 500 million Chinese who live north of the Huai River are set to lose 2.5 billion years of life expectancy combined due to the extensive use of coal-to-power boilers for heating throughout the region.

Meanwhile, using a quasi-experimental method, the researchers found very different life-expectancy figures for an otherwise similar population south of the Huai River where government policies were less supportive of coal-powered heating.

"We can now say with more confidence that long-run exposure to pollution, especially particulates, has dramatic consequences for life expectancy," Michael Greenstone, a professor of economics at Massachusetts Institute of Technology who conducted the research with colleagues in China and Israel, said in a press release.

The paper, published today in the Proceedings of the National Academy of Sciences, also contains a generalized metric that can apply to any country's environment, according to the researchers, which states that every additional 100 micrograms of particulate matter per cubic meter in the atmosphere lowers life expectancy at birth by three years.

In China, particulate-matter levels were more than 400 micrograms per cubic meter between 1981 and 2001, according to Chinese government agencies. More recently, state media have reported even higher levels, with cities including Beijing recording levels of more than 700 micrograms per cubic meter in January.

In comparison, total suspended particulates in the United States were about 45 micrograms per cubic meter in the 1990s.

As a result, air pollution has become an increasingly charged political issue in China, spurring public protests and China's government announcing last month its intent to adopt a series of measures to limit air pollution.

"Everyone understands it's unpleasant to be in a polluted place," Greenstone says. "But to be able to say with some precision what the health costs are, and what the loss of life expectancy is puts a finer point on the importance of finding policies that balance growth with environmental quality."

Going forward, Greenstone hopes the finding will have an impact on policies not only in China, but in other rapidly growing countries that are increasing their consumption of coal as well as provide additional impetus for countries to think twice about fossil-fuel consumption.

"What this paper helps reveal is that there may be immediate, local reasons for China and other developing countries to rely less on fossil fuels," Greenstone said. "The planet's not going to solve the greenhouse-gas problem without the active participation of China. This might give them a reason to act today."