Air pollution intensified in the North and Northeast, as the level of particulate matter smaller than 2.5 microns (PM2.5) was found to have reached harmful levels in many provinces.
Data from the Pollution Control Department (PCD) air quality monitoring system yesterday showed that the daily average PM2.5 levels in Chiang Mai, Khon Kaen and Lampang had risen beyond Thailand's safe level of 50 micrograms per cubic metre of air. PM2.5 measurements in those provinces were at 80.65, 64.95 and 50mg respectively.
The other PM2.5 monitoring stations in these regions, which are at Tak's Mae Sot district and Nan's Chaloem Phra Kiat district, showed daily average levels of PM2.5 had still not exceeded the safe limit, but the data showed that the levels were slowly increasing.
Currently, there are five air quality monitoring stations in nine provinces of the Northern region, which can measure PM2.5 levels and report the realtime results on the PCD website, while there is only one station that reports PM2.5 levels for all 20 provinces of the Northeastern region.
Greenpeace has encouraged the PCD to install more PM2.5 monitoring devices to cover the entire nation, to include PM2.5 level in the national Air Quality Index (AQI) and to report realtime PM2.5 levels on an hourly basis.
According to the PCD, the AQI, which does not include PM2.5 levels, showed that air quality throughout the country yesterday, including areas affected by smog in the North, were within safe levels.
It was reported in the North that dense smog throughout Chiang Mai resulted in lowered visibility. Doi Su Thep Mountain could no longer be seen from Chiang Mai's downtown area.
The dense smog also reduced visibility at Chiang Mai Airport, as planes could not be seen in the distance, but air traffic had not been disrupted.
Suthep Phongsri, head of Occupational and Environmental Health at the Chiang Mai Provincial Public Health Office, said officials were closely monitoring air quality in the province and had already prepared 64,550 facemasks for distribution, while health volunteers had been dispatched to educate people to protect themselves from air pollution.
Suthep advised people to wear a facemask when going outside when the air quality was bad and to refrain from outdoor exercise, while four groups of vulnerable persons - children, pregnant women, the elderly and persons with chronic diseases - should remain indoors and monitor their health conditions.
The ban on outdoor burning was already in place in Chiang Mai and it would be enforced until April 20 in order to prevent air pollution in the province.
In Lampang, the military led a team of officials from relevant agencies to inspect top soil mining businesses, as local people had complained that lorries transporting soil without covering their loads through their communities had intensified air pollution.
Authorities determined that many soil mining businesses did not have dust prevention measures and the volume of lorries contributed to a significant source of air pollution.