The undated photo shows busy traffic flow in Beijing. [File Photo/Xinhua]

Beijing is set to eliminate heavy-duty diesel vehicles which fail to meet National Emission Standard IV or higher, and light-duty buses failing to meet National Emission Standard III or higher by 2020, an official with Beijing Municipal Environmental Protection Bureau said.

Beijing has become the first Chinese city to fully implement the fifth phase emissions standard and eliminate "Huangbiaoche" or "yellow-label cars" which failed to meet the National Emission Standard I by the end of 2014, Deputy Director of Beijing Municipal Environmental Protection Bureau, Fang Li, said on Friday.

Fang added that a serious of air pollution control measures, including the implementation of strict vehicle emissions standards has helped Beijing to reduce the annual average density of PM2.5 to 80.6 micrograms per cubic meter in 2015, a drop of 15.5 percent from 2012. PM2.5 refers to fine particles measuring less than 2.5 micrometers in diameter, which pose a serious health hazard.

Vehicle emissions are the prime cause of air pollution in Beijing, and Beijing now has 5.61 million vehicles discharging 700,000 tons of pollutants annually.

Beijing currently imposes the National Emission Standard V for vehicles, similar to the Euro V standard in Europe. The Chinese capital city imposed the National Emission Standard I in 1999 and the National Emission Standard II in 2004. With each new standard, actual pollutant amounts drop by 30 to 50 percent per vehicle.