The directive on enhancing environmental management calls for employing measures like developing public transport, switching to vehicles using clean fuels and encouraging citizens to switch from private to public transport to reduce pollution.

The Ministry of Natural Resources and the Environment has been instructed to create national standards for vehicle emissions and suggest how they could be applied, and create a certification system to determine if a vehicle is environment-friendly.

The Ministry of Transport needs to develop a transport system utilizing environment-friendly vehicles, including those running on electricity, while the Ministry of Industry and Trade was asked to roll out policies to encourage the use of clean energy and manage fuel use in accordance with national standards.

The Ministry of Science and Technology has been instructed to issue national standards for fuels to reduce air pollution.

Earlier this month the environment ministry had called on Hanoi and HCMC to retire vehicles they deem outdated and not environmentally friendly, warning pollution is worsening in major cities.

"For now we encourage people to voluntarily give up their outdated, dilapidated vehicles," Vo Tuan Nhan, deputy environment minister, said, adding that people should switch to public transport.

Nguyen Van Phuong, deputy head of the Vietnam Register's vehicle certification department, said outdated vehicles should be evaluated for emissions and allowed to be used if they are within certain levels.

While air pollution in Hanoi, HCMC and other major Vietnamese cities is not news, it has been worsening recently, severely affecting people's health and socio-economic activities, according to the environment ministry.

It blamed dirt, emissions and construction and industrial activities coupled with unfavorable weather systems.

Hanoi has over 5.7 million motorbikes, 2.5 million of them registered before 2000. It also has over 730,000 cars.

HCMC has around 8.12 million motorbikes and over 825,000 cars, and has an estimated 30,000 new vehicles registered every month.