Temporary relief

Temporary relief

Air-pollution experts share why PM2.5 still wreaks havoc after months of applied solutions

The city of Chiang Mai, as seen from Doi Suthep, covered with heavy smog.
The city of Chiang Mai, as seen from Doi Suthep, covered with heavy smog.

Since early January, Prim* has been suffering from respiratory medical issues that her doctor attributes to the hazardous fine-dust particles known PM2.5. Residing in one of the most impacted areas of Samut Prakan, she is at her wits' end whenever heavy particulate matter or a high PM concentration level is reported along the route she takes to work and back.

"The mask helps, but my eyes begin to itch and burn when this episode occurs, and this really spoils my day," said Prim, a government officer who constantly monitors readings from the Pollution Air Quality Monitoring station to keep abreast of the situation. "Government measures to combat PM2.5 that have repeatedly been aired on television seem to suggest that spraying water from high-rise buildings and using artificial rain is the answer. This seems to only offer temporary relief.

"I hope someone will tell me how ordinary folks like myself can help address this menacing issue."

After months of air-pollution crisis, although the situation appears to have subsided in certain areas, it doesn't seem that the severity of the toxic dust particles goes away completely, especially in northern provinces like Chiang Mai, where the air pollution has constantly been reported as very unhealthy. According to data from the AirVisual air-pollution-monitoring application, Chiang Mai has often scored an unwanted podium position, being named the city with the worst air pollution in the world many times recently.

Air-pollution specialist and professor of environment engineering and management Nguyen Thi Kim Oanh from the School of Environment Resource and Development, the Asian Institute of Technology (AIT), and Asst Prof Ekbordin Winijkul from AIT's Department of Energy, Environment and Climate, believe the answer to successfully tackling PM2.5 would need to be not just a collaboration between the local and central governing bodies, but public participation. While there is no quick fix to the predicament, the best approach would be through participatory measures and better public awareness, to help ensure everyone's on the same page when it comes to dealing with the sources of PM2.5.

Nguyen and her team have been monitoring PM2.5 in Thailand since 2000. And the reasons behind its continuing presence, according to her findings, are local emissions sources.

"Traffic congestion creates much higher emissions from vehicles per kilometre driven. Secondly, the open burning of agricultural waste and solid waste. And thirdly, industry. The precursors of the secondary aerosol or particles are the gases that are emitted from all the aforementioned sources. The precursors, for example, include sulphur oxides, nitrogen oxides, volatile organic compounds emitted from industrial combustion, vehicle exhausts, open burning, etc. Meanwhile, ammonia comes from livestock and agricultural fertiliser use."

In the past two decades, the professor admitted contributing sources to the hazardous dust particles have greatly intensified.

"PM2.5 is composed of different components that are toxic and carcinogenic. Given that they are tiny, tiny particles, they can get deep into the lungs when we breathe."

Further explaining PM2.5 is that it is directly emitted from combustion of fossil fuel and biomass, which are classified as primary particles. They are also formed in the atmosphere from the precursors that are also emitted from combustion, called secondary particles or secondary aerosol.

To add fuel to fire, the air-pollution expert said new cars have added to traffic congestion, and an increased burning of rice straw in urban communities is due to increased domestic consumption and export of rice.

Meteorological factors such as dry and wet seasons also contribute to the severity of the impact in certain areas.

The holistic approach is recommended here, said Nguyen, because the issue of PM2.5 needs to be addressed at its root cause.

"The public has to be given a bigger role in addressing the issue, because, for one, they will need to change their lifestyle in some areas. As we know, the local sources impacting this issue include road traffic/vehicles, open burning of rice straw and solid waste, industries around Bangkok and surrounding provinces, and to some extent street cooking. The public has to see how they can help curb these contributing factors.

"This could be done in many ways. They can start by properly maintaining their vehicles, using public transport, carpooling, avoid driving during rush hour. Traffic laws can be amended to discourage drivers to enter overly congested areas at certain times of the day by charging them to enter that part of the city. More climate-friendly contraptions can also be built for street-food vendors so the emissions produced will not be hazardous to the environment and their health."

Rice-straw pellets are fuel derived from rice straw. (Photo courtesy of Asian Institute of Technology)

Nguyen and her team of researchers have worked to create a novel idea to turn agricultural waste of rice straw into pellets, and to avoid open burning of rice straw in fields, hence reducing hazardous emissions.

She said rice-straw pellets can also be used for cooking.

"During our project we burned rice-straw pellets in a gasifier cooking stove and found that it produced no visible smoke and the cooking pot had no soot at the bottom afterwards.

"Measurement showed the emission rate of PM from cooking with rice-straw pellets to be only about 1/3 of that from open-field burning for every kilogramme of straw burned."

It's a win-win, she said, adding: "When we collect rice straw to make pellets for cooking, we can, one, avoid open burning in the field, hence reducing harmful emissions, and, two, turn this agricultural waste into fuel which when used is quite clean.

"We thus reduce the emissions of PM2.5 and its precursors, which react in the atmosphere to form secondary particles and other toxic gases such as CO, benzene, etc, that are emitted from open burning.

"This also reduces the consumption of other types of fuels such as charcoal, loose rice straw and LPG, also used in cooking."

On the other hand, Asst Prof Ekbordin suggested stronger international collaboration at the government level between neighbouring countries to better address the PM2.5 problem, especially when dealing with transboundary pollution that is exacerbated by forest fires and crop-residue open burning.

Moreover, Thailand's central and local governing bodies have to also work in tandem to produce favourable results.

"Both governing bodies have to synchronise their efforts," he said. "Laws against open burning have to be strictly enforced by the local governing bodies, which should be given a larger say in managing this problem. Stronger ties between local and central government agencies should also be formed to discourage this practice from continuing."

Ekbordin also stressed the need for the government to offer farmers better incentives to stop the practice of open burning.

"If we don't allow them to burn, what are the better options for them? Maybe the government can offer social benefits or even benefits that would positively impact the community they reside in.

"At the end of the day, a large portion of these farmers don't own the farm land they plough and so are dependent on daily wages."

Ekbordin was also on the same page as Nguyen when he suggested the need to have long- and short-term regulations set in place to fight the various sources contributing to PM2.5.

"Long-term could include modes of transport -- having Thais opt for public transport rather than driving their own vehicle. However, for this to happen, we would need to have better and safer public transport implemented first.

"Short-term should be the banning of open burning. Better awareness campaigns have to also be implemented, teaching farmers the dire consequences of their actions. Today there are still a certain number who don't realise that this practice has far-reaching consequences. We have to see that every farmer realises its gravity."

*not her real name


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