Air Quality Monitoring in Bangkok - What's your PM 2.5 ?

Update 2019 and 2020 : see bottom page | Update 2021

Air Quality Ranking : Chiang Mai on Top on 7 March 2021

AirVisual App screenshot : Chiang Mai tops the list (again! once more!) on 7 March 2021. Bushfires to blame. PM 2.5 at the time was 267 micrograms per cubic meter. Just like in March 2020.


Air Quality Alert

Bangkok is known to have a very limited number of public parks. Fortunately, off the main streets, trees can still be found along the streets and in private properties. However, empty plots are slowly but surely disappearing, with people moving out to the outskirts of the city, and property developers moving in.

We are near to the end of the cold season in Bangkok, en for about three weeks now the air quality in Bangkok and surroundings has been covered regularly in the English-language newspapers in the city. This is unusual. Actually, the 'common' knowledge now says that the environment now is considerably better than some years ago.

On 8 February 2018 there was a quite visible haze over Bangkok, not only in the far distance and when looking towards the sky, but also when looking at nearby high-rise buildings. The same day the Pollution Control Department issued a warning that unhealthy levels of particulate matter would make life a bit uncomfortable for a few more days. That day PM 2.5 (smaller than 2.5 microns) levels ranged between 69 and 95 microgrammes per cubic meter during most of the day. We recall that these small particles are most likely to be settling in the lungs and cause all kinds of havoc in the body. The Environmental Protection Agency states that levels lower then 50 microgrammes are 'satisfactory', though as far as we know it is a case of the lower the better. More than 150 microgrammes is 'very unhealthy', and the values in between are unhealthy. Of course, people with underlying diseases will always be at risk earlier.

The EPA of the U.S. states that higher levels can cause : premature death in people with heart and lung disease, nonfatal heart attacks, irregular heartbeat, aggravated astma, decreased lung function and increased respiratory symptoms. Personally, we noticed some stinging in the eyes when walking outside.

Interestingly, PM 2.5 levels are not regularly reported by the Thai Pollutions Control Department. We recommend using the App provided by the department ( called Air4Thai ) which provided a few times a day updated measurements of the Air Quality Index, which apparently is based on PM 10, ozone levels, and on a number of gases in the air such as CO and NO2 . There are measurements from a number of locations around Bangkok, but now from interesting areas such as Sukhumvit Road or Silom Road. Rama IV road measurements are probably those closest to the center.

But you can also check out various provinces in Thailand. This is especially important before embarking on the trip to the Chiang Mai area and the North, which suffers from a bad environment during part of the cold season months (pollution by slash and burn practices).

Results of air quality monitoring with Acer AM100

(partial) Screen Shot of results of air quality monitoring with Acer AM100


Do your know your 'personal' PM 2.5 level ?

It may be useful to have an idea about the air quality at your own location, and also especially your indoor air quality, since that is where you spend most of your time. We have looked into this from time to time, but consumer goods measuring air quality have not clearly been available at an affordable price until recently. However, this year you clearly have a choice of small appliances available. We searched on a popular online shopping site, and noticed a range of small non-branded devices (or at least not from well known brands) produced in China. Quite understanbable, since there most be a big market in China now, what with the recurrents problem of severe pollution in its major cities.

A further search online, and we found a well designed product by Acer, named AM100, which we bought for about 200 U.S. Dollar, transport and immigration costs included from Amazon, when it was priced as a promotion. We checked later on and now it is sold at about 250 U.S. Dollar.

It measures about 10cm x 10 cm x 4.5 cm and provides quite a few data : PM 2.5 levels, PM 10 levels, TVOC (Total Volatile Organic Concentrations) level, and derived from that CO2 Equivalent Value level. (this latest level is not directly measured). You set it up with your home Wifi, and connect to it with Bluetooth. When connected to Wifi, it will relate the measurements to the 'cloud' and you will be able to see some graphs with average hourly results etc. When you go outside and use only Bluetooth (you can of course elect to connect to another Wifi, but that would be a bit laborious to do each time you move), you still can make measurements, but they will not be stored in the 'cloud'.

On 8 February we put the device on our balcony outside and in the morning we got some PM 2.5 levels starting from around 95 microgrammes per cubic meter, slowly decreasing to about 40 microgrammes per cubic meter in the late afternoon. Note : the manual states that the device might be less reliable when used outside, but we think also from other observations that it works well enough. Acer also uses recommended values that are lower than the ones mentions above by the EPA. You should strive to have measurements below 15 microgrammes per cubic meter to be in the 'good' category.

Not to worry too much : When measuring inside our apartment, we usually find levels in the 5 to 15 microgrammes range. When we start using our air conditioner, the first 15 minutes or so, the level may be in the 15 to 30 microgrammes per cubic meter range. This probably means we should have it cleaned. A puzzling problem (at least for me) are the levels of 'Volatile Organic Concentrations' which sometimes are too high (unhealthy for sensitive persons). We have not yet figured out what causes these higher levels (it can come from a variety of 'gases' lurking around your home such as paint components, cleaning products, cooking, etc.). The device picks up 'scents' very easily. For instance, we cleaned our eye glasses with a German produced impregnated tissue, and the TVOC went through the roof for a few minutes. When airing the room, the TVOC usually goes down (generally TVOC levels are lower in the outside air than in the inside air).

The device gives measurements available on your mobile device through Bluetooth, which works find. We were capable of connecting the device by Wifi. This enables getting graphs showing pollution of longer time periods, hours of days, if you want. However, after an update of the app by Acer, we never managed again to connect be Wifi. So, there is some kind of bug, and the company seems not to be willing or able to do anything about it.


Improving the Indoor Air Quality

Hatari Air Purifier, sold in Thailand

Hatari Air Purifier ( HT-AP 12 )


We have been preoccupied with our indoor air quality for many years. Actually much more so than with the outdoor air quality in Bangkok. The reason is that for many years we have been heavy smokers. Filtering the air, we figured, may at least reduce the levels of indoor pollution (difficult to open windows in the heat of Bangkok most of the time).

For this purpose, over the years, we have bought a number of air purifiers with HEPA filters and carbon filters. The HEPA filters are supposed to get rid of small particles such as PM 2.5 and PM 10 . We used these air purifiers blindly since up to now, we had no way of measuring indoor air quality. By the way, you can buy air purifiers all around town, especially in the department stores. There are a few problems : they are expensive (twice the price of what you would pay in U.S. or Europe), and even more important, there is an issue with obtaining replacement filters. Simply put, it is easy to buy an air purifier, but one year later you may not find an adequate replacement filter because the department store does not supply it anymore or never did in the first place (especially when newer models of air purifiers have replaced the older models).

The best air purifier we ever had was a brand called SCANA, made in Koreas. Unfortunately, they have disappeared from the market.

But now, since a year or two, the local Thai company HATARI, produces an air purifier, at a very reasonable price of less than 5,000 baht. (HEPA) Filters (always buy them in bulk with your original purchase, to be on the safe side!), are sold at a price below 1,000 baht. You can find them at HomePro, and we found out they work well enough.

How do we know? When we switch them on, they lower the levels of small particles reliably. Within 15 to 30 minutes, levels of PM 2.5 will usually go down to 1 or 2 microgrammes per cubic meter, and levels of PM 10 likewise to between 1 and 4 microgrammes per cubic meter.

TVOC is a different matter. When values are low or moderate, no need to worry. When higher, these filters (also the SCANA air purifier mentioned above), have only a modest and slow effect (if any). You are better off opening your windows for awhile, this may be more efficient.

Acer AM100 Air Quality Monitor

Acer AM100 Air Quality Monitor


In conclusion, nowadays your can access overall air quality levels around Bangkok and Thailand be using the ' air4thai' app by the Pollution Control Department of Thailand. You can measure your personal environment with a device such as the Acer AM100 Air Quality Monitor. And you can efficiently lower levels of small particles at home with an HEPA-filter equipped air purifier.

P.S. : We do not have any commercial arrangement with either Acer or Hatari, just providing hopefully useful info here.

Update 2019

Environmental pollution is much in the news at the beginning of 2019. Problems started to emerge at the end of 2018, and the idea is now that pollution in Bangkok may have become a seasonal event, occurring in the so-called cold season.

Headline in the Nation newspaper, regarding Air Pollution Levels in Bangkok
Headline News in the Nation newspapers regarding pollution levels in Bangkok

It seems that there are almost daily updates, at least in the English-language newspapers. Fine dust seems to be the present problem, as before, with PM 2.5 levels often between 50 and 100 microgrammes per cubic meter. Occasionally the 100 microgrammes level is also broken. Interestingly, our own observation shows that the best periods of the day are usually between 3 and 7 P.M., while early in the morning, late evening and during the night, levels are high. So if you want to do some outdoor running, you know when to do it.

Not quite clear what is the present reason for bad outdoor pollution levels. The nightttime presence of a lot of fine dust, is a bit of a puzzle. Traffic is heavy, as usual. There has been a lot of building construction the last few years, though that is now possibly leveling off. Then again, there are major public works underway, with construction of mass transportation systems, mostly in the suburbs of Bangkok.

PM 2.5 levels in Bangkok during two days in Januari 2019, in Bangkok, Thailand

PM 2.5 hourly levels on saturday 12 and sunday 13 January 2019 in Bangkok. Notice dip in the afternoon, and levels reaching sometimes around 100 microgrammes per cubic meter in the late evening and at night. Date generated by IQAir AirVisual App, which we much recommend. Data on this internationally operating App, are usually a bit higher than those provided by Air4Thai, a Thai App for Thailand.

Some people protect themselves from breathing foul air, and masks are readily available even in convenience stores. Personally, we had to look around a bit to find something really suitable for the purpose. Some cheap masks seem to filter out small particles (N 95 Respirators level), but they do not fit well all around the mouth and nose, making them not quite useful, since air will certainly always find the way of least resistance. We found some good masks at Homepro, not too expensive, and with a valve, provided by the famed 3M company, called 9001V N95 Respirator. Hopefully though, we can stop using them in the next few weeks.

Update 2020

It is now possible to say : we have a yearly recurring phenomenon. For some reasons, it clearly started (or was somehow noticed firstly) end 2017-beginning 2018, and the situation of poor air quality during the 'wintermonths' has returned the next 2 years. It started now again at the end of 2019, and continued throughout the whole of januari. A minority of people are wearing masks, we noticed it are mostly the 'office workers' that do so. The situation is regularly reported about in the now single English-language newspaper the Bangkok Post. The response of the government agencies, is disappointing as before : they seem to be rather despondent, like, what can we do about it ? And if we do something about it, will the people like it (who wants to leave their car at home?). So nothing substantially is being done about it, though we are regularly told something is going to be done about it. Interestingly, during the New Year period when at least half of Bangkok disappears into the provinces, and there are much less cars on the road, we noticed the air remained poorly. So, it is a complex situation, and different measures will have to be taken to address it.

In the long run, if this continues, it will affect the global perception of Thailand. Then, the day it dawns that less tourists are coming to the country, all kind of measures will suddenly be applied.

Mid to end March the skies had cleared up a bit around Bangkok. Traffic was greatly diminished since there was a serious (pre)lockdown situation as a response to the Covid-19 pandemic around the world. So things should also be better in Northern Thailand. However, it was not to be. Apparently this was the time for bushfires to appear. Things got particularly bad towards the end of March. On 29 March Bangkok Post reported a total of 624 uncontrolled fires around Chiang Mai the previous day, with hundreds of more fires in the surrounding provinces of Mae Hong Son and Nan. There was even a fire coming close to the ascent to Doi Suthep. On 27 there was a reading of 925 microgram per cubic meter of P.M. 2.5 particles, the highest ever recorded in Thailand, and definitively toxic for human beings.

At the top of this page, you see the present reading (morning 29 March 2020) when Chiang Mai again topped the list of most polluted cities in the world. This at a time when traffic is much reduced due to the Corona virus. There is talk of doing something about it, as in the previous years. Personally, I would say : follow the money.


Update 2021

Can not elaborate further. Nothing changed over the past year. On 7 March 2021 Chiang Mai reached the top op the rankings on AirVisual. Actually, Bangkok has been suffering likewise since about 3 months by this time. It is worth pointing out that there is a moderate economic crisis going on, with a clear reduction in road traffic, especially during the weekends. Actually, in the midst of the Covid-19 Pandemic, people are clearly traveling less, certainly when there is no clear purpose. Factories also likely produce less and therefore produce less pollution. The reason for the persistent poor air quality : be exclusion, it is likely to be land clearing by burning waste after the harvest. We have also become aware of a process whereby the crops are actually burned around the time of harvesting sugar cane, because it makes the harvesting easier and more profitable. No clear effective measured announced. The data become more widely known, and the authorities like every year behave as if the problem has just arrived, and promise to try to do something about it.

P.S. : As far as we know, Bangkok has not yet reached the Top position in poor Air Quality, as compiled by AirVisual.