Experts identify causes of Beijing's air pollution

Air pollution has been a persistent headache for Beijing, prompting experts to weigh in with their thoughts on what is causing the problem, as well as possible ways to fix it.

In January, Beijing began to publish hourly air quality reports based on an international standard of measuring PM2.5, or airborne particulate matter smaller than 2.5 micrometers in diameter, which experts say pose the most serious health hazard.

Monitoring data show that the average PM2.5 concentration in the Chinese capital is nearly double the national standard, which is set at 35 microgrammes per cubic meter.

Beijing used to release air quality readings based on the measurement of PM10, or particulate matter less than 10 micrometers in diameter, but its PM10 data has never met the national standard and currently exceeds the standard by 20 percent.

Air pollution control has been a priority for the city's policy makers since the "Defending the Blue Sky" project was launched in 1998.

A five-grade classification of air quality on the basis of pollution indices has been used in Beijing, with grade I being the best and grade V the worst. Days with grade I or II air quality are considered "blue sky days."

Annual "blue sky days" have increased from 100 in 1998 to 286 in 2011.

However, environmental authorities in Beijing announced in early June this year that they will stop counting "blue sky days," as the total could hardly reflect the specific situations in different parts of the city.

Experts say although the city's air quality has been improving gradually, the progress remains far from acceptable and serious challenges in improving air quality loom ahead.

VEHICLE EMISSIONS

Experts believe that vehicle emissions are the greatest source of Beijing's air pollution.

More than 5 million vehicles are currently registered in Beijing, and the number keeps climbing, said Chai Fahe, deputy head of the Chinese Research Academy of Environmental Sciences.

Chai said although the number of cars in Beijing is only half that in Tokyo, the frequency of use is much higher. Beijing cars run 45 km per day on average, while those in Tokyo run an average of 19 km per day.

More than 70 percent of Beijing's cars are concentrated in the downtown areas, he added.

Li Kunsheng, an official with the Beijing Environmental Protection Bureau, said China still has no efficient laws and regulations for eliminating high-polluting vehicles

Du Shaozhong, another official in the bureau, suggested that Beijing should strengthen measures such as encouraging the scrapping of high-polluting vehicles and improving fuel standards.

Hao Jiming, an academician with the Chinese Academy of Engineering, said the city should improve its public transportation networks, as the high number of private cars and slow-running vehicles on the road increase emissions of harmful particles.

Hao also said the city should readjust the locations of residential and working areas in order to reduce traffic flows.

REGIONAL POLLUTION

Experts have also warned that air pollution in Beijing cannot be eased without taking measures to curb emissions of pollutants in surrounding cities.

Tang Xiaoyan, a professor with Beijing-based Peking University, found that when air pollution is heavy in Beijing, the nearby cities of Taiyuan, Shijiazhuang and Hohhot, as well as Tianjin municipality, also face heavy pollution.

Wang Yuesi, a researcher with the Chinese Academy of Sciences, said hazardous heavy metals found in the air over Beijing come from ferrous metal smelting and coal burning in the Beijing-Tianjin-Hebei area.

Data show that Tianjin municipality and Hebei province both have a large number of cement, steel, oil refining and petrification industries that burn a total of 350 million tonnes of coal per year. About 24.5 percent of the PM2.5 in Beijing comes from those industries.

Wang Yuesi said in addition to the Beijing municipal government, the central government should also pay more attention to tackling pollution in the neighboring provinces of Hebei, Henan and Shandong.

Zhu Tong, a professor with Peking University, suggested building a scientific research and data collection platform to investigate and monitor the air pollution situations in Beijing as well as nearby cities and provinces.

Moreover, a management platform that transcends administrative boundaries should also be established to coordinate and direct pollution control work in different provinces and cities, Zhu added.