The government of the Guangdong provincial capital is considering an odd-even license plate number system to curb the city's air pollution in the future.

The Guangzhou City Bureau of Environmental Protection is now soliciting public opinion on a draft plan to introduce an odd-even restriction system.

Experts, scholars and local residents are welcome to deliver comments to the bureau via in-person visits, letters, phone calls, email and WeChat messages before December 7, the bureau said in a statement published on its official website on Wednesday.

According to the draft plan no mid-sized trucks, heavy-duty diesel vehicles, heavy trucks, bulk material transporters, concrete mixer trucks, building material transport vehicles or other vehicles that cause air pollution will be allowed to operate in the city's urban areas, while other vehicles would be required to operate according to an odd-even restriction system when a red air pollution alert — the highest such warning — has been issued in the city.

When an orange alert is issued, only mid-size trucks and heavy-duty diesel vehicles will be allowed to operate according to the odd-even restriction system, while heavy trucks, bulk material transporters, concrete mixer trucks, building material transport vehicles and other vehicles that may cause air pollution are banned from running in the city's urban areas.

And no heavy trucks, bulk material transporters, concrete mixer trucks, building material transport vehicles or other vehicles that may cause air pollution are allowed to run in the roads and streets in the city's urban areas when a yellow alert has been raised, the draft plan stipulates.

But on-duty vehicles of the People's Liberation Army, fire engines, ambulances, engineering rescue vehicles, buses, coaches, school vehicles, funeral cars, new energy vehicles and related vehicles that have been granted licenses will be exempt from the new odd-even system, the draft plan read.

"Guangzhou is expected to become the first in the southern province of Guangdong, one of the country's economic powerhouses, to introduce an odd-even car restriction system to help ease air pollution," as per the plan.

According to the traffic police department Guangzhou, which has a population of more than 16 million, has now registered nearly 2.5 million vehicles. This large number has been seen as a major cause of the city's air pollution.

Guangzhou has been limiting car registrations since July 2012. Only 10,000 new license plates are now being granted monthly, through lottery and public auctions.