Thick haze causes overcast sky in Bangkok

Many people in Bangkok, who woke up this morning and prepared to leave for work or school, may have wondered whether it would rain today. The overcast sky was not caused by rain clouds, but a thick haze of pollution mixed with fog, or smog.

Visibility was so poor that high-rises, normally visible from a distance, had disappeared into the haze. It was as the sun rose higher and haze dissipated that visibility started to improve and sky became less overcast.

Sugunyanee Yavinchan, director-general of the Meteorological Department, explained that the overcast sky was caused by a mixture of morning fog and air pollution, due to the accumulation of dust particles in the atmosphere as the result of the weakening the high pressure system and static air flow.

She said the cold weather at high altitude prevented airborne dust particles from rising higher into the sky, accumulating at a low altitude as a result.

Meanwhile, the Pollution Control Department reported that the PM2.5 levels in Bangkok and its suburbs this morning were lower than yesterday, ranging from 37.3-81.2µg/m³ (microns) compared to yesterday’s 38.5-95.8µg/m³.

He said that high humidity of 88%, coupled with the airborne dust, made the sky look gloomy and caused poor visibility.

Bangkok Governor Chadchart Sittipunt said that PM2.5 pollution in Bangkok started to improve today, although PM2.5 levels in some areas remain high, thanks to a drop in the burning of farm waste in surrounding provinces, as Nakhon Nayok and Prachin Buri.

He said PM2.5 levels remain high in Bang Rak, Pathumwan, Chatuchak and Lat Krabang districts due to traffic congestion in the inner city and the burning of farm wastes in suburban areas, such as Lat Krabang district.

He predicted that air quality would improve this weekend.