City Chairman Nguyen Duc Chung announced the decision on Wednesday and told the Hanoi Urban Environment Company (URENCO) to ensure the sprinklers on the trucks are in good condition.

Several district leaders had asked for the trucks to water congested streets to mitigate the air pollution at a meeting earlier that day.

Nguyen Thi Nang Mai, Vice Chairman of the Bac Tu Liem District People's Committee, said there are many major construction sites in her district, including the Nhon-Hanoi Railway Station on the second metro route, which generate a lot of dust.

Nguyen Manh Ha, chairman of Long Bien District, said at the meeting that streets should be cleaned more often during the dry season and when pollution is bad.

The strategy will first be trialed in Hoang Mai District, cleaning two streets there once a week.

Water trucks were grounded in early 2017, with the chairman saying washing did not make the city cleaner.

Fifty vehicles that vacuum dust and trash were then bought from Germany. Each collects 1.5 cubic meters of dust a day, the same volume as 12 workers.

Since then the cleaning trucks are only used by URENCO when the city hosts a large event and to clean the streets around Hoan Kiem Lake before and after they become walking-only during weekends.

Hanoi's alarming pollution has been making headlines since September.

The air quality index (AQI), which indicates pollution, went past 200 for four consecutive days starting on November 7 before topping 300 on November 12.

An AQI level of above 100 is considered unhealthy for humans.

In October the capital identified the sources of its pollution as traffic emissions, domestic cooking coal, construction sites, and animal farms.

In December the Ministry of Health issued a 14-item list to help deal with air pollution, including close supervision of air quality, use of masks and improving personal hygiene.