Deputy director of the Hanoi Environment Department Le Tuan Dinh

Local newspapers days ago cited a GreenID report as showing that the air was polluted five days a week. 

According to Dinh, the conclusion was made based on figures from the air quality monitoring station located at the US Embassy. This is a location with high traffic density, near Giang Vo - De La Thanh crossroads and large construction works.

After reading the report, the environment department invited representatives of the US Embassy to exchange views about the figures.

The air monitoring station at the embassy is a sensor station, while the method of calculating AQI (air quality index) applied by the US is different from the one applied by Vietnam. 

In general, the figures from sensor stations are less accurate and informative than the figures provided by fixed stations. Therefore, they can be used only to research and survey trends of environmental changes, but they don’t reflect the air quality of the whole city.

“The figures provided by the sensor station are not reliable. In other words, the quality of the air in Hanoi is not as bad as reported by GreenID,” Dinh said to the local press.

Also, according to GreenID, while the dust concentration has decreased slightly compared with the same period last year, the PM2.5 fine dust concentration in Hanoi is always higher than the international standard.

Dinh confirmed that sometimes in rush hours, on some belt roads and the areas where there are construction works, the PM10 and PM2.5 concentration is higher than the permitted level. 

The environment department has been assigned to set up a network of air quality monitoring stations in the city and implement air automatic monitoring projects in some areas. This serves forecasting and early warning of pollution in each area.

The monitoring stations show that the air quality in the city meets the average level in all months in dry and rainy seasons. The air quality in residential quarters and IZs has gradually improved. 

The benzene index is on the rise year after year because of the increased use of fossil fuel (petrol) and the number of vehicles. 

However, the index is still within the safety line in accordance with the Vietnamese standard.

The biggest problem is the PM10 dust concentration in some places and at times the city exceeds the national standard by 1.5-2 times.

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