"The implementation of stricter automotive emission standards will improve the city's air quality in the long run," he said.

Li said Beijing is well prepared for the implementation of the new emission standards, as the city has started providing a cleaner supply of gasoline and diesel with a concentration of sulfur no more than 10 ppm since last May.

Li said automobiles meeting the stricter emission standards are all equipped with a fuel particulate filter, which also requires a higher standard of fuel - with a sulfur content of no more than 50 ppm. Otherwise, the filter will be damaged and cause the vehicle to break down.

According to Li, despite the fuel supply with lower concentration of sulfur provided in Beijing, the quality of fuel supplement in neighboring cities still lags far behind the capital.

Some cities around the capital are still providing gasoline with a sulfur content around 150 ppm and diesel with a sulfur content of no more than 2,000 ppm, he said.

"It's necessary that the capital, together with its neighboring cities, jointly deal with pollution," he said.

zhengxin@chinadaily.com.cn