Household fuels major source of Beijing smog: study

Household fuels exceed power plants and cars as a source of smog in China, according to a new study which found that the government could dramatically improve air quality with more attention to an overlooked source of outdoor pollution - residential cooking and heating.
"Coal and other dirty solid fuels are frequently used in homes for cooking and heating," said Denise Mauzerall from Princeton University in the US.
"Because these emissions are essentially uncontrolled they emit a disproportionately large amount of air pollutants which contribute substantially to smog in Beijing and surrounding regions," said Mauzerall.
Households account for about 18 per cent of total energy use in the Beijing region but produce 50 per cent of black carbon emissions and 69 per cent of organic carbon emissions, researchers said.

In the Beijing area, households contribute more pollutants in the form of small soot particles (which are particularly hazardous to human health) than the transportation sector and power plants combined, they said.
In the winter heating season, households also contribute more small particles than do industrial sources.

According to researchers, high levels of air pollutant emissions are due to the use of coal and other dirty fuels in small stoves and heaters that lack the pollution controls in place in power plants, vehicles and at some factories.
"The use of solid fuels (coal and biomass) for heating and cooking in households contributes directly to exposures in and around residences and is a major source of ill health in China," researchers said.

Illness caused by air pollution was a leading cause of premature death in China, ranking between high blood pressure and smoking as risk factors, researchers said.
Researchers used a sophisticated air pollution model to evaluate the benefits of reducing residential emissions on air pollution levels in Beijing and the surrounding region in the winter of 2010.
The region in the study, which has a population of 104 million people, and frequently has air pollution levels more than six times higher than what the World Health Organisation considers a safe limit, included Beijing and the surrounding Tianjin and Hebei provinces.
Researchers ran computer model simulations in which they removed a varying amount of residential emissions in Beijing alone as well as the entire Beijing-Tianjin-Hebei (BTH) region and found that reducing residential emissions resulted in corresponding drops in outdoor pollution levels.

"Our analysis indicates that air quality in the Beijing region would substantially benefit from reducing residential sector emissions from within Beijing and from surrounding provinces," said Mauzerall.
The findings were published in the Proceedings of the National Academy of Sciences.