BEIJING, Jan. 6 -- Beijing car owners with emissions-heavy models can now earn more money from scrapping their vehicles after the city raised its subsidy for doing so by an average of 2,000 yuan (321.8 U.S. dollars), environmental protection authorities said Tuesday.

According to the new plan, owners who used their vehicles for more than six years and disposed of the vehicles at least one year earlier can receive an average of 8,000 yuan subsidies. The highest subsidies for cars will reach 8,500 yuan, and 21,500 yuan for heavy duty diesel vehicles.

The plan is to be effective throughout 2015 and 2016.

Owners who trade in their old vehicles for new ones will receive another subsidy for purchasing new cars.

Old-vehicles used for more than 10 years with high pollutant emissions are still running on the road, said Li Kunsheng, with the Beijing Municipal Environmental Protection Bureau.

"They are the target of our pollution monitoring work," he said.

The new plan is to be announced in detail soon, according to Li, and all vehicle-owners who scrapped their vehicles after Jan. 1 are qualified to apply for the new plan.

Beijing's average PM2.5 density in 2014 dropped by four percent compared with 2013, but some pollutants rebounded, said the municipal environmental protection bureau earlier this week.

The average density of PM2.5, airborne particles smaller than 2.5 microns in diameter, was 85.9 micrograms per cubic meter in 2014, compared with 89.5 micrograms per cubic meter in 2013, the bureau said in a statement Sunday.

The reading was still 1.5 times higher than the national standard of 35, which was set by the State Council in 2012.

As part of efforts to curb pollution, Beijing reduced coal use by 2.6 million tonnes to keep it below 19 million tonnes. The capital also removed 476,000 outdated vehicles from roads and shut down about 375 factories in 2014.

In 2015, Beijing aims to cut PM2.5 index by around five percent and reduce the emission of sulfur dioxide and nitrogen oxides by six percent.