The northeastern province of Khon Kaen reported the country's worst air pollution for the second time this week.
The province showed an Air Quality Index (AQI) level of 210, the level of PM2.5 dust at 100 micrograms per cubic metre of air and PM10 dust at 166 micrograms per cubic metre of air on Thursday, according to a daily report by the Pollution Control Department (PCD).
The three figures were all beyond the country's safety limits of 100 in AQI, 50 micrograms of PM2.5 and 100 micrograms of PM10.
Loei province reported a 111 AQI level, 55 micrograms of PM2.5 and 81 micrograms of PM10.
The northeastern region had only three air quality-monitoring stations in Nakhon Ratchasima, Khon Kaen and Loei, while the PM2.5 measuring devices were only at Loei and Khon Kaen.
Assoc Professor Dr Kittichai Triratanasirichai, a former president of Khon Kaen University, said the pollution in Khon Kaen had worsened mainly due to the burning of sugarcane and rice stubble and from exhaust fumes.
“If you look from a plane, you will clearly see smoke from sugarcane plantations,” he said, adding that farmers preferred to burn the sugarcane stubble because it was the most convenient way to clear the fields, but this aggravated the smog.
“Exhaust fumes are also a big problem. The amount of dust in the air increases considerably during rush hour,” he noted.
However, the northern province of Chiang Mai, which usually would have haze during this time of year, and Bangkok, which has been choked by pollution for days, reported safe levels in air pollution.
In the North, the PM2.5 levels were reported between 14-88 micrograms with the beyond-safety PM2.5 level cited in Lampang (Muang district's tambon Phra Baht, Mae Mo district's tambon Sop Pad, tambon Ban Dong and tambon Mae Moh) and Phrae (Muang district's tambon Na Chak).
Bangkok and five vicinity provinces reported PM2.5 levels within the safety limit and it was predicted that the PM dust may increase slightly but still be in "safe" amounts on Friday, the PCD said.