Emissions of sulfur dioxide, an air pollutant produced primarily by burning coal, have fallen by 75 percent in China since 2007, while SO2 emissions in India have jumped 50 percent, according to a new study by researchers at the University of Maryland.

China and India are the world’s two biggest coal-burning nations, but the University of Maryland study showed that a host of measures implemented by China over the past decade — including improved pollution control technologies and levying fines on polluters — have sharply cut sulfur dioxide emissions. These reductions were achieved even as coal usage increased 50 percent in China and electricity generation grew 100 percent.



India, by contrast, has seen sulfur dioxide emissions soar as the country has built new coal-fired power plants but has not imposed significant pollution controls. The study, published in the journal Scientific Reports, says India may already have become the world’s largest emitter of sulfur dioxide.

Despite China’s progress in slashing SO2 emissions — which cause acid rain, haze, and numerous health problems — the country still has a severe air pollution problem because SO2 makes up only 10 to 20 percent of particulate air pollution, the study said. Not until other sources of pollution from vehicles, factories, and agriculture are cleaned up will China’s air become significantly cleaner, the study said.



The University of Maryland researchers quantified the changes in SO2 pollution in China and India by drawing on data from emissions reports, a NASA satellite-based ozone monitoring instrument, and weather aircraft that measure SO2 and other pollutants.