Heavy pollution in northern China has cut average life expectancy there by at least five years, according to a study published Monday. The report, authored by American, Israeli, and Chinese researchers, found that people in southern China live, on average, 5.5 years longer than the 500 million living in the north, and that northern mortality rates are higher across all age groups. The findings are based on official Chinese data on pollution levels and health indicators, dating from 1981 to 2001.

The study attributes much of this discrepancy to the widespread use of coal north of the Huai river. Beijing has provided northerners with free coal boilers since the 1950s, to help heat homes during the winter. Those living south of the Huai did not receive coal boilers, resulting in a significant gap in coal particulates.

"public health costs are larger than we thought."

According to the researchers, the concentration of coal particulates in northern China was 55 percent higher than in the south, which has contributed to higher death rates — primarily from cardiorespiratory diseases. The study also found that an increase of 100 micrograms of particulates per cubic meter correlates to a three-year drop in life expectancy at birth. North of the Huai, particulate concentrations were 184 micrograms higher than in the south.

According to the New York Times, this week's study is the first to exclusively rely on official Chinese figures. The Chinese government has long maintained that burning coal is necessary to the economic livelihood of those in the north, despite protests from environmental and health advocates. Recent data from the US Energy Information Administration show that as of 2011, China was burning nearly as much coal as the rest of the world combined. Experts hope that this week's study may finally push the government to change its policies.

"It highlights that in developing countries there's a trade-off in increasing incomes today and protecting public health and environmental quality," said Michael Greenstone, MIT professor of environmental economics and one of the paper's authors. "And it highlights the fact that the public health costs are larger than we had thought."