Tran Quang Lam, director of the municipal Department of Transport, said they will cooperate with the Vietnam Association of Motorcycle Manufacturers to evaluate motorbike emissions at eight stations.

"We will compile data on emissions to evaluate the motorbikes' general status, and report to the city’s People’s Committee to seek approval for an emission management plan in the city," Lam said.

The evaluation will be performed with permission from citizens, so as to make them more aware of the impacts of motorbikes' emissions on the environment, he said.

Emissions from cars, trucks and buses will also be monitored closely, Lam said, without revealing specific plans.

Saigon, Vietnam's largest metropolis with 13 million people, now has about 8.1 million motorbikes and 825,000 cars.

The city authorities said exhaust from around 10 million vehicles is one of the three major causes of air pollution in the city, besides smoke from 1,000 large factories and dust from numerous construction sites.