The Pollution Control Department (PCD) issued a warning yesterday that poor air quality caused by PM2.5 particulates in Bangkok and the surrounding provinces is likely to persist for about one month.
The warning came as the level of PM2.5 was found to exceed the safety limit of 50 microgrammes per cubic metre (µg/m³) in 19 areas within Bangkok yesterday after air quality had sharply improved on Jan 9 and Jan 10.
PM2.5 particulates reduce visibility and cause the air to appear brown and hazy when its levels are elevated.
According to the PCD, three areas were found to have critical levels of PM2.5. The PM2.5 level on Lat Phrao Road was at 86 µg/m³, 85 µg/m³ in Wang Thonglang district, and 72 µg/m³ in Din Daeng district on Rama III Road in Bang Kholaem district.
Construction projects and emissions from cars are major contributors to air pollution while a lack of wind has allowed pollution to accumulate in the air, according to the PCD.
Pralong Damrongthai, the department's director-general, called on residents in Bangkok and its surrounding areas to brace themselves for the up-and-down air quality situation for about a month.
"I think we'll see the air quality getting better and worse like this for a month. We'll have to maintain surveillance," he said.
He noted that the current situation was not as critical as it was in December when the level of PM2.5 in some areas exceeded 100 µg/m³ and posed health threats.
Mr Pralong said the air quality was expected to improve sharply and return to normal in three to four years when most of the mass-transit system construction work throughout Bangkok is expected to be completed.
A planned switch to B20 biodiesel and an expected increase in hybrid and electric vehicles is also raising hopes of improving air quality, he added,
Meanwhile, Tara Buakamsri, country director of Greenpeace Southeast Asia, said that high levels of PM2.5 will remain in Bangkok even after construction projects are completed and cars are powered by electricity.
