AirVisual measures showing Hanoi city’s air quality is the world's most polluted are partial and inaccurate, according to the Agency of Environmental Protection under the Hanoi Department of Natural Resources and Environment.On September 26, in the ranking for the ten most polluted cities in the world out of the 10,000 monitored by the AirVisual application, Hanoi is listed at the top position (the AQI index is always above 200, i.e bad level), followed by Jakarta (Indonesia) and Ho Chi Minh City.
Fine dust pollution is a huge problem in Hanoi. Photo: Zing
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"The US monitoring station only collects data of PM2.5 dust particles and as it is located at a T-junction, which is subject to heavy traffic and where major construction works are underway, thus, the indicator is higher than that in other places," Son said.
He added that in the process of urbanization, numerous construction works and high density of vehicles are causing air pollution.
Besides, as it is now season change with very few wind and rain, the whole city is blanketed with smog, so dust remains dense without being dispersed, Son explained.
Le Thanh Hai, former deputy general director of the National Center for Hydro-Meteorological Forecast, said that inversion radiation is also a cause of air pollution.
At night, thermal radiation from the ground dissipates into the atmosphere, creating a layer of smog at low altitude, preventing dust to be dispersed, which explains why during the day, the air is always polluted, except for a little time in the afternoon when, the under the heat of the sun, hot air that rises to higher altitude and spreads around, Hai explained.
Meteorological experts said that air pollution in Hanoi is only improved when the monsoon comes or it rains, or until cold front arrives.
According to the agency's forecast, Hanoi's air quality will be improved in about 10 days.
