The PM2.5 haze has been blanketing the city of Bangkok for 3rd consecutive day. Photo courtesy of Monre

PM2.5 haze hits Bangkok for 3rd consecutive day while people advised to WFH

The city residents are alerted of the PM2.5 pollution throughout the weekend as the air inversion still plays a crucial factor while other regions are also experiencing a high level of PM2.5 concentration resulting from forest fires and farm clearing

The capital has been hit hard by this year’s haze for the third consecutive day, with the 24-hour PM2.5 fine dust concentration levels crossing the safety limit set at 50 micrograms per cubic meter (µg/m³)_and even touching the hazardous threshold of 100 µg/m³ in most of its areas. 

Thailand still sticks to this 50-µg/m³ safety limit as the new limit set at 37.5 µg/m³ has not yet been in effect until June. Any levels between 51 to 90 µg/m³ are considered as the levels that will “start to affect health” (Orange), and any levels beyond 90 µg/m³ are considered as the levels that “affect health” (Red). 

The dust level of 100 µg/m³ is considered as the hazardous threshold, and any level beyond this is considered as a crisis and needs an urgent meeting of the national committee to address measures to tackle the problem immediately.

Over the past few days, Bangkok has experienced PM2.5 with levels crossing 100 µg/m³ in a number of areas. On Wednesday, the Bangkok Metropolitan Administration (BMA) reported that the dust concentration levels measured in late morning stood around 57 to 101 µg/m³ (76.5 µg/m³ on average). The dust levels then rose a day later to between 71 to 130 µg/m³ (94.6 µg/m³ on average), with 70 areas having the dust that “affect” health (Red) and 24 more having the dust that will “start to affect health” (Orange). 

Today, the situation has slightly improved, with the dust levels measured around 50 to 93 µg/m³ (70.4 µg/m³ on average). The Red areas are down to four, but still, up to 66 areas are still having dust that can “start to affect health”.

The BMA has issued a warning for people to be still watchful over the weekend as the air inversion still plays a crucial factor. It has also recommended people work from home to avoid health impacts as well as lowering down the dust concentration in the atmosphere.

The seven-day PM2.5 forecast for Bangkok and 17 northern provinces. Credit: PCD

Dr. Pinsak Suraswadi, Director-General of the Pollution Control Department (PCD) said haze this year is likely to worsen than the past few years as economic activities have returned following the post-Covid 19. 

In the city, the prime source of PM2.5 is clearly a result of heavy traffic and incomplete combustion of diesel based car engines. It’s exacerbated by the dust particles produced by factories in the city and nearby provinces, over 800 of them, as well as the dust produced from forest burning in the North and open-air farm residues burning in the Central Plains, he said. 

As recorded yesterday, over 1,200 hotspots were detected in the North, prompting the Environment Ministry to step up its efforts to suppress the activities. It will set up a war room in the North next week to synergise the work across different agencies, Dr. Pinsak said, and these hotspots must be halved to help lower down PM2.5 and the impact.

The PCD chief said the rise in hotspots might have resulted in the change in forest fire and biomass management as it has shifted from zero-burning to limited burning, and the measure may have not yet been well implemented by concerned agencies. 

Zero-burning, he said, prompted people to rush into burning their biomass at once over the past years of implementation, thus releasing PM2.5 in the atmosphere tremendously, while the limited burning, if not properly regulated, may cause a similar problem and uncontrolled fires.

Aside from the sources of PM2.5 in the country, a number of hotspots have also been widely detected in neighbouring countries. Dr. Pinsak said the PCD has already contacted its focal points for cooperation in suppressing the pollution in the meantime.

Tackling the right sources of origin

An independent environmental expert and former specialist of the Office of Natural Resources and Environmental Policy and Planning (Onep), Sonthi Kotchawat, has shared his observations, citing that air inversion plays a crucial role in the PM2.5 pollution at present.

There are a number of hotspots in Cambodia and Laos, 1,723 and 923, respectively as recorded by GITSDA. However, he views that the dust from those hotspots is not the prime source of the current PM2.5 pollution in the city, considering the dust levels in the East next to those countries are still relatively low.

Mr. Sonthi said incomplete car combustion, dust particles from factories, and open-air farm residues burning are still the prime causes of the pollution in the city, and if the dust levels are beyond 90 µg/m³ for three consecutive days, governors can enforce the environmental laws by suspending the activities concerned immediately.

“The fact is Bangkok, the North, and the Northeast have been experiencing high levels of PM2.5 that exceed 100 µg/m³ for several days already without any law enforcement against the sources of origin. Or is this because an election is near, so compromises first, not peoples’ health?,” asked Mr. Sonthi.

Thailand has been experiencing haze seriously over the past three or four years since it came up with better air pollution measurements, which exposed exceeding levels of dust particles that are harmful to people’s health like PM2.5 both in the capital and other regions.

Since, the issue has been addressed as a national agenda, which directs comprehensive planning aimed at tackling the sources of the air pollution, which are different among regions.

For instance, in the capital, the main sources of PM2.5 haze are incomplete combustion of car engines, especially diesel-based vehicles, intensive construction, as well as pre-harvest burning of farm leftovers in provinces in the Central Plains. In the North, on the other hand, the main sources of the pollution are farm clearing and forest burning.

The situation is often exacerbated by bad weather created by an air inversion, under which a warmer air overlays the cold air and acts as a lid while the air underneath becomes stagnant, thus trapping the pollution below.

In spite of the national agenda and plans, the country is still struggling with PM2.5 haze, which has apparently gone from bad to worse.