Air Pollution in Thailand

Chiang Mai Air Pollution - Hazardous

Air pollution is a significant problem in Thailand.

Northern, Northeastern, and Central Thailand all suffer from seasonal air pollution from seasonal fires and air patterns.

Even Southern Thailand can suffer bouts of air pollution from nearby Sumatra Island.

Also, year-round air pollution plagues the larger metropolitan areas in Thailand because of the preponderance of diesel-burning vehicles.

Air Pollution Measurements

Air pollution runs the gamut of particle sizes (PM) and sources, though two sizes in particular are of interest: PM2.5 and PM10. These two combine to generate an AQI score. While the AQI has a range of 0-49 for a rating of good.

No Safe Level of Air Pollution

In fact there is no safe level of air pollution. The WHO needs to revise its guidelines in line with other pollutants with no known safe level, such as lead in drinking water.

Measuring Thailand's Air Pollution

There are several sources of ongoing measurement of air pollution in various parts of the country. In addition, as much of the air pollution is caused by fires set for various reasons (discussed below), the FIRMS firetracker satellite data helps to visualize the degree of that source of the problem.

Causes of Air Pollution in Thailand

There are four main causes of air pollution in Thailand, and a different mix of these is present in different parts of the country. Roughly they can be summed up as: Corn, Construction, Diesel, and Mushrooms, though not in the order of importance, corn accounts for the largest share in Northern Thailand.

  • Diesel emissions (and other vehicle emissions) - predominant in cities, the primary polutant in large metropolitan areas, especially Bangkok. Increasing over time.
  • Agricultural burning - predominant in the countryside, with major causes being annual burn-back of jungle areas to clear for agriculture, and burning agricultural waste, increasing dramatically over the past 10 years due to increasing demand for, and therefore supply of, corn as a cash crop grown for processed corn products (corn syrup predominantly) used in Thai agribusiness. Increasing over time.
  • Construction air pollution - Industrial processes such as cement manufacturing, as well as road and building construction contribute to PM2.5 as well as PM10 and larger dust particles. Many construction vehicles used to haul dirt and waste are left uncovered, as are most construction sites. Increasing over time.
  • Jungle arson - predominant in the countryside, with the objective to illegally clear jungle for planting or to create conditions for an increase in wild mushroom production for export markets (mainly China). This is a significant problem in more rural areas such as Mae Hong Son province. In many cases the arsonists/mushroom exporters are not local people who live near the forests but interlopers who are there only for the purpose of burning the jungle and harvesting mushrooms.

Additional causes of air pollution include coal-burning power plants, though that is not widespread throughout Thailand.

Seasonality of Poor air quality

There is an obvious seasonality to Thailand's air pollution. This is due as much to the sources of air pollution, as the weather and and climate patterns. There is an increase in agricultural burning during the hot season, but that is still performed during other seasons. The main issue is a lack of rain and wind, and is contributed to due to temperature inversion effects and wind patterns.

In the hot months there is significant wind from the West which is a source of agricultural burning and jungle arson. In the winter ithere is also

In the wet months there is also higher humidity which increases dry depositon, which in turn reduces PM10.

Dry conditions also increase pollutants due to greater efficiency such as increases in ozone from vehicle emissions, and the longer burning periods for fires.

Despite all of these issues, agricultural burning and jungle arson are the two primary sources of air pollution and they are done more often during the dry months.

Solutions to Air Pollution in Thailand

It is obvious that the solutions to these issues is to create strict economic disincentives, as all of these are caused by economic activity that is at least nominally sanctioned by the government (through their inactivity). Corruption and sloth (aka greed and laziness) are the primary reasons for the ongoing increase in air pollution in Thailand.

In Thailand there is a significant inability for the private sector to litigate its rights. Not only are courts succeptible to corruption, but even complaints about negative impacts that are caused by particular businesses are liable to be counter-sued due to defamation. Public Health is not taken seriously if there are wealthy elites connected to the offending behavior.

At the same time, the utter timidity of the military-led government to impose even a modicum of restraint against various sectors of the economy means that even the simplest solutions are not even entertained.


Ban/fine diesel-burning vehicles from the center of cities. Ban new diesel-burning vehicles from being manufactured or imported at a future date. London and Singapore have the lead in this area and their policies should be emulated. Note that non-diesel vehicle emissions are hazardous, especially ozone.


Ban/fine construction pollution that can be mitigated. Cover construction locations and construction-carrying vehicles. Increase requirements for construction industry production pollution controls.


Corn is a bit difficult to deal with as the alternatives are not much better: sugar cane and palm sugar production. Nevertheless, the real costs to the environment for burning agricultural waste should not be externalized to the growing communities, but should be a part of the market price of the commodities. Alternative economically viable methods of waste disposal need to be innovated and deployed.

In addition, massive increase in the consumption of sweeteners in terms of public health impacts needs to be measured and public health campaigns waged to reduce sweetener consumption in children as well as adults. The epidemic of diabetes is causing a huge impact on healthcare and health outcomes for the country.


Making the export of wild mushrooms illegal, and enforcing that law would be an excellent first step. Fining and jailing offenders would go a long way to disincentivizing jungle burning behavior.

What to do about air pollution in Thailand

Besides moving away during the worst air pollution months (Jan-May) there are two specific things to do:

  • Use air purifiers
  • Wear N95/N99 masks

DIY air purifier

Air purifiers need not be expensive. In fact one can create a DIY air purifier with a simple HEPA filter and a common fan. Fans run 500-1,000 baht in Thailand, and one can order a 30cm x 30cm HEPA air filter on Lazada for under 300 baht. A new fan is not needed if one simply has a functional fan already in the house. The aiflow is significantly disrupted, however, therefore using another fan for air purification may be needed if one does not have an extra one lying around.

N95 and N99 air filter masks

N95 and N99 rated masks provide 95% and 99% filtration respectively. Interestingly, even common surgical-style masks are effectively N40 in rating (80% particle filtering with a 50% fit). However, ouble masking with surgical masks does not provide much more protection (see below).

For hazardous air pollution situations, it is important to wear rated masks and not just any facemask. Particle counts above AQI 50, or even less should be seen as hazardous air, as there is no known safety level for PM2.5 and PM10 particle air pollution.

Some facemasks provide limited air pollution protection when it comes to PM2.5 and PM10, such as the popular Japanese Pitta mask. It is important not to just wear any mask, but those that have ratings by trustworthy manufacturers.

Air filter masks and breathability

Some people intuitively believe that masks limit oxygen levels and recommend using them outdoors in moderate exercise situations. However, there is no evidence of this and there is research indicating the same amount of oxygen is available with or without masks.

Air filter fit test

It is vital that an air filter be worn properly in order to work properly. This is called a fit test.

Double Masking

According to actual research, double masking doesn't provide much additional protection, but can make it more difficult to breathe. While intuitively double masking might make sense, the science indicates otherwise.

Doubling mask layers modestly improves a masks filtration effectiveness. Doubling mask layers can also reduce breathability.

Stick with a single good mask.

Health benefits of wearing a mask

deaths from pm2.5

There are easily measured health benefits of wearing a mask, but it is not necessarily intuitive. The largest impact is on blood pressure, and is directly measurable. There is constriction in blood vessels with increased AQI. Lung capacity is also directly impacted by increased AQI. Children, pregnant women, the sick, and the elderly are also more affected by poor air quality. Children especially have an increased lung surface area for their body mass, and their heart rates and respiration is more rapid than adults, meaning that per kilogram they breathe 50% more air than adults.

Air pollution-related deaths are due to several factors:

  • Heart attacks and strokes (72%)
  • Lung cancer (14%)
  • Bronchitis and emphysema (14%)

How long do masks last

Masks do reduce in effectiveness over time, though not dramatically. There is good evidence that masks can last more than 2 weeks of daily use, possibly much longer. However, masks should not be washed or cleaned. When done so, their effectiveness is significantly impacted.

Particle Counters

There is one mainstream particle counter that is widely seen as the de facto standard for personal use: The Kaiterra Laser Egg. It costs around 150 USD or 5,000 Thai baht, and is available online from Kaiterra, as well as, Central department store and Lazada.

The Laser Egg can network over 2.4ghz WIFI and interact with IFTTT including the ability to log readings to a Google Spreadsheet, and connect with the Kaiterra app.