Acting director of the Environment Observation Centre, Nguyen Van Thuy, announced this at a workshop on Air Quality Improvement and Urban Transport held by the French Embassy on Wednesday.
Thuy said that in inner city districts, pollution was made worse by the high concentration of dust and dirt carried in by dense traffic.
While average population density is one to two thousand people in suburban areas, in inner districts such as Dong Da, it is up to 38,000 people per square kilometre.
According to a study Air quality Management Action Plan for Ha Noi by Dr Sarath Guttikunda of the US Desert Research Institute in 2008, the annual amount of particulate (dust, grime) matter in the city was 150 microgrammes per cubic metre.
The World Health Organisation recommended limit of 20 microgrammes per cubic metre, said Jacques Moussafir from ARIA Technologies, a French company specialising in pollutant dispersion and air quality modeling.
He added that the city now had nearly four million vehicles - and that the number was growing by 12-15 per cent a year.
This is why many people, especially children, have serious health problems caused by the dust and smoke.
Massafir said that to improve air quality, comprehensive measures were crucial, including regulations on emission reduction, public awareness and environmentally friendly means of transport such as an underground subway system.
(V.N.N)