By PRATCH RUJIVANAROM
The Northern Meteorological Centre (NMC) said yesterday that weather conditions during this period were the main factor for the current air pollution in the northern region.
Wind from the southwestern direction during the summer months also brings smog and very fine particulate matter from open burning locally and in neighbouring countries, which results in air pollution that threatens people’s health.
Worapoj Khunawiwatthan-angoon, a meteorologist at the NMC, said the recent haze problem in many northern provinces, especially Chiang Mai and Lampang, was associated with the sharp rise of hotspots upwind, in areas southwest of the Chiang Mai-Lamphun Valley.
“During this time of the year, the wind is blowing from southern and western directions and as there is a lot of burning both in the region and neighbouring countries in upwind areas, the smog from the burning is carried downwind,” Worapoj said.
The Geo-Informatics and Space Technology Development Agency’s (GISTDA) data showed there were 81 hotspots on Tuesday in nine northern provinces. These hotspots were mostly in Tak, Mae Hong Son and Nan, as the hotspot counts of these provinces were at 30, 20, and 19 respectively, while there were many more hotspots in Myanmar.
Tuesday’s hotspot count was considerably higher than the previous days. As on Sunday, there were only 13 hotspots in the region.
Hotspots, where open burning areas were detected by satellites, were the main source of very fine particulate in the air and resulted in health threats, lower visibility, and disruptions to businesses and tourism.
Haze information from neighbouring countries in Asean, provided by the Specialised Meteorological Centre, showed that very dense smog covered large areas along the Thailand-Myanmar border, especially in Mae Hong Son province in Thailand and Karen state in Myanmar.
Worapoj said that due to the current severe haze problem in the North, people should refrain from doing outside activities, especially during the morning. Colder temperature in the morning hours will trap the air pollution on the ground, but the hotter weather in the afternoon will make the air pollution rise higher along with warm air and spread into the wind.
He also said that the bad air quality was predicted to last until Sunday, as rains and summer storms were forecast in the upper part of Thailand from Sunday until Wednesday, which will greatly reduce the air pollution.
According to the Pollution Control Department’s air quality real-time monitoring website, the level of particulate matter smaller than 2.5 microns has been increasing beyond the country’s safe limit of 50 micrograms per cubic metre of air, in many provinces.
As of yesterday, the PM2.5 daily average level in Lampang’s Mae Moh district reached a harmful level of 76.79 micrograms, while in Chiang Mai it was at 76.28 micrograms, and in Tak’s Mae Sot district it was 62.45 micrograms.
However, Chiang Mai and Lampang were not the areas with the most severe air pollution if visibility were considered.
These two provinces had visibility at 10 kilometres compared to only three kilometres in Mae Hong Son and Lamphun, due to dense smog.