Air quality in Chiang Mai

Is Chiang Mai a polluted city?

Chiang Mai is a city located in the northernmost part of Thailand, not far from the borders of both Laos and Myanmar. It has a population of over 127,000 people, with a PM2.5 rating of 32.3 μg/m³, putting it into the ‘moderate’ bracket of how polluted a city's air quality is, according to the standards set by the US Air Quality Index, with this reading having been taken as an average over the year of 2019. It ranks in at 16th place within Thailand’s most polluted cities on the IQAir website listing, as well as coming in at number 372 in regards to the worlds most polluted cities.

Despite its moderate air quality ranking (air quality index readings of PM2.5 between 12.1 to 35.4 μg/m³) there are several things to take into account. It ranks much further ahead in terms of poorer air quality than Bangkok, which comes in at number 48 out of the 50 cities ranked in Thailand according to their pollution levels. Bangkok is famous for its levels of smoke, haze and pollution, mainly caused by its vehicular emissions, so for a city such as Chiang Mai to be ranked much higher than Bangkok, with a population of over 10 and a half million people, it goes without saying that Chiang Mai has its fair share of pollution problems.

Like most cities in the northernmost part of Thailand, the poor air quality rating does not come mainly from industry and the pollution from vehicles, although of course that is a contributing factor, but rather from smog and haze drifting in from neighboring Laos and Myanmar, as well as the continuous burning of forest and farmland that occurs every year. These factors cause the pollution and PM2.5 levels to soar over certain months of the year, making Chiang Mai a very polluted city during these times, with two of its months having air quality index ratings that put it in the ‘unhealthy’ bracket, namely a PM2.5 reading between 55.4 to 150.4 μg/m³.

These ratings would make it difficult for those with respiratory issues, as well as being hazardous for vulnerable demographics such as children, the elderly and those with weakened immune systems. As again with all cities in Thailand and the region, there are times of the year, namely during monsoon season when the air quality improves significantly and actually falls into the World Health Organizations target air quality readings (0-10 μg/m³), so overall it fits with its yearly average of a moderate rating, with brief periods of respite and then months with unhealthy levels of smoke and fine particulate matter (PM2.5 or PM10) permeating the air.

What are the worst months for Chiang Mai’s air quality?

The months of February through to April are when the air quality is at its worst, towards the end of the dry season and subsequently leading into monsoon season when the air quality drastically improves after April. Looking at the air quality index readings from 2019, it is clear that in January the PM2.5 is still sitting at its average rating of moderate, but as February comes around it suddenly leaps to a rating of 47.2 μg/m³, a reading which is double that of the previous month, moving it into the unhealthy for sensitive groups bracket. This means that anyone with preexisting respiratory conditions such as asthma may find themselves at risk and should take appropriate action to keep themselves safe.

Moving on to March, it once again doubles in the 2019 readings, hitting a yearly peak of 98.7 μg/m³, putting it up by yet another bracket into the unhealthy rating (any readings between 55.5 to 150.4 μg/m³ would class it in this group).

Following on with April it still remains in the unhealthy range at 74.1 μg/m³. In 2018, PM2.5 concentrations in March were almost three times the January levels and were Unhealthy according to the U.S. Air Quality Index. During the haze season, passenger planes are occasionally unable to land in Chiang Mai because of the poor visibility, a clear indicator that these worse months are indeed stifled with high levels of smoke and haze and an overall very poor quality of air.

Is the quality of air improving in Chiang Mai?

According to the data shown on the IQAir website taken from official PM2.5 readings, the quality of the air in Chiang Mai seems to be getting worse instead of better. In 2017 the yearly average was recorded at 22.7 μg/m³, with the following 2018 showing a yearly average of 24.5 μg/m³. Moving on to 2019 and the yearly average had increased to the aforementioned 32.3 μg/m³. This is a trend showing that the quality of air is decreasing, and seems to be showing no signs of slowing down even in 2020 with COVID-19 bringing most of the world to a standstill.

This shows that the air quality is most definitely on the decline, and the pollution would be coming from the burning of organic material, which will be discussed in further detail. The burning of such material releases a variety of noxious fumes and pollution into the air, with both PM2.5 and PM10 to be found, being formed from the chemical reactions of toxic materials such as nitrogen dioxide (NO₂) as well as sulphur dioxide (SO₂) and nitric oxide (NOx). The burning of volatile organic compounds (VOC’s) can further compound the air quality and make living conditions worse. When the data is observed it is clear that the quality of air has significantly worsened, and drastic action may perhaps be needed to stop it from continuing in this trend.

Whilst the practices of slash and burn farming have been around for a considerably longer time before they came under the scrutiny of the worlds eye due to their extremely disastrous and prominent effects on neighboring regions and countries, these practices will eventually have to brought to an end as soon as possible, due to the globalization of farming industries as well as the population boom. What was once an acceptable and effective way to return nutrients to the soil in preparation for the next crop plantation, has instead devolved into a problematic practice, and without its cessation, there is no doubt that the data will continue to show increasingly poor air levels, both in Chiang Mai and all the other cities and countries in the region.

What are the health impacts of polluted air in Chiang Mai?

Health effects of living in a city that is subject to poorer air quality are numerous, with both short- and long-term effects. Many studies show the findings of how PM2.5 and PM10 can affect our health, with the higher AQI rating months of February through to April being of chief concern.

The health effects of being exposed to smoke and haze caused by the burning of organic materials as well as vehicle emissions can cause an increased risk of cancer, particularly that of the lungs, along with irritation to the respiratory tract and skin. In 2017 a study was conducted by the World Bank, which found that the overall economic costs inflicted upon Thailand by pollution went from 211 billion Thai Baht (6.9 billion USD) in 1990 to 871 billion Thai Baht (28.8 billion USD) in 2013. This shows that the cost has quadrupled over the 23 years, just as an example of the far-reaching effects of air pollution in a country.

The air pollution levels in Chiang Mai, particularly in regards to PM2.5 and its extremely small size, give it the ability to enter the bloodstream via the lungs of people who are breathing it in on a daily basis. For people who may have to continue to go to work and commute during the worst months may find themselves at a high risk of developing chronic obstructive pulmonary disease (COPD), an umbrella term which includes many respiratory illnesses under it such as chronic bronchitis, asthma, Emphysema and other conditions that can lead to a reduction in full lung function.

Outside of respiratory symptoms, the circulatory system can also be gravely affected due to the ability of PM2.5 found in smoke and haze to enter the bloodstream and thus be circulated around the body. This can cause a rise in cardiac events such as increased risk of heart attack, as well as arrhythmias. This makes those with preexisting conditions such as heart disease, congestive heart failure and coronary artery disease particularly at risk when exposed to high levels of PM2.5, and as such they should consider assistance in the form of an air quality map, available on the AirVisual app and well as real time AQI ratings available every day on the IQAir website. With this data available, people who are at risk can make more informed decisions on when to stay indoors and away from the pollution, or if need be, they can purchase higher quality masks, as available on site.

How is the quality of air in Chiang Mai when compared to Bangkok?

When compared to the capital city of Thailand, Chiang Mai prominently stands out as being ranked fairly far ahead of Bangkok, once again with Chiang Mai coming in at 16th place compared to Bangkok’s 48th place ranking. When observing the PM2.5 data collected over the last few years, it is of interest to note that the air quality rating of Bangkok is actually improving in its yearly average, whilst the pollution levels in Chiang Mai are getting worse.

In 2017 Bangkok presented a yearly average air quality rating of 27.6 μg/m³, followed in 2018 by a slightly improved rating of 25.2 μg/m³. When compared with 2019, further improvement was shown with an average yearly concentration of 22.8 μg/m³, a feat that is fairly impressive when you consider the massive population as well as the huge vehicular emission.

In contrast, the 2017 reading for Chiang Mai was 22.7 μg/m³, showing that in that year its pollution levels averaged a lower ranking than that of Bangkok’s. The same occurred in 2018 with a rating of 24.5 μg/m³, where it still came in lower than Bangkok however with a worse reading than the year prior. The big difference came in 2019 when the pollution levels caused a yearly average reading of 32.3 μg/m³, putting it well ahead of Bangkok with a significant jump from the prior year's reading. This indicates that the current air quality of Chiang Mai is now worse than Bangkok.

How can the pollution levels in Chiang Mai be improved?

On a larger scale, air quality in Chiang Mai can simply be improved by reducing the amount of organic material being burnt, thus reducing the amount of black carbon, PM2.5 and VOC’s being released into the atmosphere. Cooperation must come in the form of assistance from the neighboring countries of Laos and Myanmar, with stricter rules regarding their own slash and burn farming, which can add to the air pollution levels in Chiang Mai, which already has its own problem with the burning of crops and forested areas. Authorities in the past have sprayed water into the air during the haze season to try to reduce the amount of dust, as well as ‘seeding’ the atmosphere to create artificial rainclouds, but this doesn’t really address the root cause of the issue, instead being a transient fix to a much larger problem.

There is an urgent need to reduce emissions from factories and vehicles, as well as smoke from agriculture burning, although it would seem that due to the cities smaller size and lesser population, the main culprit for the reduced air quality and increase in smoke and haze with each year is coming from the burning of organic matter in the agricultural sector. Government initiatives in the past have threatened action and arrest against those responsible for these practices, although so far little or not enough action has been taken.

After the 2019 haze crisis in Thailand in which schools in Bangkok were forced to close for several weeks due to a very persistent haze, more attention is being turned to this issue, but one must reckon as to whether it is too little too late. On a smaller scale, Individuals in the city can take steps in their daily life to reduce their own personal pollution emissions by reducing the amount of time they spend using their cars, resorting to taking public transport, actively switching to greener fuel alternatives, and most importantly being aware and informed of the worsening air quality and what they can do about it as they go about their day to day lives.