|A forest fire in Indonesia has caused thick smog to envelop HCM City and some parts of southern Viet Nam. — Photo vnexpress.net
HCM CITY — A forest fire in Indonesia has caused thick smog to envelop HCM City and some parts of southern Viet Nam, Deputy Director of the Southern Hydro-meteorological Centre Dang Van Dzung said.
"Dry smog occurred recently both at sea and on land. So the main cause of this condition is from some other place that has diffused over Viet Nam," he said on Wednesday.
Dung was quoted by vnexpress.net as saying, "After we re-examined the weather information from Asian countries in the region to rule out any active volcanoes that left only the haze resulting from the forest fire in Indonesia."
The centre's staff based their study on wind speed and diffusibility. He said that the time the haze from Indonesia entered the southern provinces of Viet Nam, was between Monday and Wednesday.
The expert said that was the cause of the recent thick smog, and added that on October 2 and October 3, Singapore, Malaysia and south of Thailand were also affected by the haze from Indonesia.
It was not due to a forest fire haze in Indonesia spreading to Viet Nam on the ground, because of the distance between two countries. However, forest fire haze usually emits huge amounts of smoke, with winds blowing dust, according to the expert.
He said data from the meteorological observation stations reported that a thick smog was seen first on October 4 at Con Dao Island, Ba Ria-Vung Tau Province, after that it spread to other islands.
"On October 5, the smog was seen in Ca Mau, Can Tho provinces, Dong Thap Province's Cao Lanh City, and then HCM City," he said.
"This condition was seen the most yesterday (October 6) and lasted until evening," the expert said, and added that the fog, which technically occurred since humidity reach 90 per cent early in the morning, was called "wet fog" but when the humidity came down to 75 per cent, it was called "dry fog".
The expert said HCM City's heavily-polluted environment could also cause "dry fog". However, data from meteorological observation stations revealed that dry fog occurred widely in southern provinces and HCM City, both at sea and on land recently. So, the Southern Hydro-meteorological Centre had to re-examine data in order to assess the real cause of this condition. Dzung said the dry fog phenomenon never occurs at sea or in the forest.
It only happens in urban areas which has a large industrial zones, construction, and high density of vehicles that cause environmental pollution such as in HCM City, Can Tho and Bien Hoa cities. – VNS