The Beijing Environmental Protection Bureau has started soliciting public opinion about its sixth phase emissions standard, the world's strictest, due to be implemented starting Dec 1, 2017.

The new standard, which covers light vehicles, heavy vehicles and heavy motors, was drafted according to the world's strictest emissions standards, the bureau said in a statement.

Currently, vehicles in Beijing need to meet the fifth phase emissions standard, which went into effect in 2013 and is equivalent to the Euro V emissions cap.

According to the sixth phase standard, light vehicles must cut emissions by 40 percent, and heavy motors, such as those used in buses, must cut emissions by 50 percent.

Research shows PM2.5 particles, which are emitted by vehicles, make up 31 percent of total pollutants. International practice has shown that strict emissions standards are important for cutting pollution and improving air quality, the statement said.

The bureau estimates that pollutants emitted by vehicles will be cut by as much as 30 percent by 2022.

Smog has become a major environmental issue in Beijing. The central government has ordered the city to cut PM2.5 by 25 percent from 2012 levels by 2017.