Last week Guangdong province upgraded its emission standards in the provincial capital Guangzhou and eight adjacent cities for light vehicles to the National V, which requires sulfur content in fuel to be no more than 10 parts per million (ppm), one-fifth of the National IV's 50ppm.

Huang Qingfeng, senior engineer at Vehicle Emission Control Center of Guangzhou, said the emission standard upgrade requires both the fuels and the vehicles' exhaust meeting the standard.

"The fuels in Guangzhou met the standard beforehand, and the vehicles standard as the second step," he said.

Beijing applied the National V standard as the first in September 2013, then Shanghai in April 2014. Both Beijing and Shanghai municipalities required the vehicles meeting the standard at first, and then the fuels.

Liu Jun, intake and exhaust system section manager at Pan Asia Technical Automotive Center Co, said that "A module would be added for upgrading, and it cost several hundred yuan each car. When a car model has 10-thousand-unit sales, the upgrading cost would be millions of yuan."

Ni Hong, new vehicle registration director at vehicle emission control center under Ministry of Environmental Protection, said there exists flaws in the national standard and regulations. In the specified test for exhausts, some products have passed; but in using, they may have poor performance.

Zhejiang Geely Holding Group's Chairman Li Shufu supported the higher emission standard should be applied as soon as possible and the carmakers should avoid becoming the makers of air pollution.

He also called for a transparent schedule for new standard upgrading as Geely has already been well-prepared for the National V standard, but it increased the cost.

If the prices were increased, customers would choose the lower price ones with lower standard but having higher pollution. When rival with the lower standard products at a similar price, they lose money and hurt Geely, according to Li.

Li proposed an air quality law amid the annual session of the Chinese People's Political Consultative Conference, China's top political advisory body, started on March 3.