Unhealthy levels of particulate matters have persisted in Bangkok, with the hardest-hit area on Sam Sen Road in Phra Nakhon district.
The Pollution Control Department on Monday morning reported the hazardous particle levels in the air in Greater Bangkok ranged between 47 and 91 microgrammes per cubic meter.
The safety threshold is 50 mcg.
Calm wind limits dispersal of pollutants and high pressure traps air pollution one km. above the ground, said the department.
Meanwhile, the meteorological department forecast a drop in the temperature in the next two days due to mildly cold air mass from China and expected rain in some areas.
In an attempt to alleviate the dust problem, the Department of Land Transport stepped up checks on exhaust fume emissions of passenger buses and trucks.
On Jan 19 alone, out of all 2,560 vehicles tested, 29 vehicles were banned from roads after the checks found them, emitting exhaust fumes over required standards or over 45 percent.
Warnings were given to 127 vehicles with 30-45 percent exhaust fume emissions to improve the vehicle engines.
Public members can file a complaint about the vehicles with excessive exhaust fume to the hotline 1584.