World's most polluted cities - and no, Thai cities do not make the list - IQAir Ranking explained

[JohnNThai]

As a lot of you have heard, read and felt in the last two months, the air quality in most parts of Thailand has been really bad to even hellish. To a point even, that Thai cities make international headlines around the world. As of this month, IQAir has released their annual report on the most polluted cities in the world for 2022, with their records going back to 2017 and being the go-to air-monitoring website. I took this chance to analyze the data and cross reference it with other local data. Please note that at no point am I downplaying anything regarding the catastrophic air quality in Thailand. Here's what I found: 

 

First of all, contrary to popular belief, Chiang Mai is not the most polluted city in the world. Nor is it the most polluted city in Thailand. IQAir's live ranking only includes 90 cities from around the world, on average two per country, sometimes less, sometimes more. We are looking at only 65 countries represented in the ranking, so what we get is a very narrow and diluted view of not only the global air situation but also the situation here in Thailand, which affects us most prominently, hence the big 'clickbait' headlines you see throughout media. Luckily, IQAir offers the function to see beyond the curated list and see a live monitoring of other cities in Thailand.

 

As an example for the discrepancy: 

As of today (26.03.2023), Chiang Mai was listed as the #1 polluted city in the world ranking again with a average AQI of 205, but the Thai live ranking reveals that Chiang Rai had an average AQI of 491, followed by Mae Hong Son, Nan and Bueang Kan (Isan). Now is this clarification making the situation any better? Absolutely not. This just acts as an example to show that the problem is far more widespread than one city and that we cannot and should not determine a #1, but rather determine regions, patterns and effects from multiple sources, so it can be fought, because I don't think that solely eliminating Chiang Mai's air pollution would help the North or even Thailand as a whole. It is too complicated for that. But for those that are interested where Chiang Mai ranks globally (hint: it is nowhere near the top), keep reading.

 

A much better way to determine patterns regarding air quality in Thailand, and around the world, is to look at yearly averages for PM2.5 pollution. For that we can look at data from IQAir, the WHO and the Pollution Control Department of Thailand, though I will primarily be relying on IQAir's data in this instance. In the case of Chiang Mai, it ranked #1208 (18.4 μg/m3) in 2022 and based on the average yearly pollution from 2017-2022 it ranks around #695 (25.6 μg/m3). Bangkok ranks on average around #890. Nan, as the most polluted Thai city on average, ranks around #364 (34.1 μg/m3). Thailand overall ranked #57 (18.1 μg/m3) out of 131 countries. The most polluted cities in the world would be Patna, India with a average pollution of 114.5 μg/m3, followed by Wotan, China with 104 μg/m3 and Lahore, Pakistan with a average of 100.1 μg/m3. The most polluted countries are Chad, Iraq and Pakistan, with China and Indonesia being the most polluted in East and South-East Asia.

 

I compiled a list of averages of 20 bigger cities in Thailand with data for the year 2022 and a list for cities that have past recorded data in the timespan from 2017-2022. You will see quite a few cities more for only 2022, as these have just received their monitoring stations and thus their yearly average in 2022.

 

For 2022 (numbers representing PM2.5 in (μg/m3)):

1. Nan (30.4)
2. Lampang (27.2)
3. Khon Kaen (25.1)
4. Samut Sakhon (23.9)
5. Ubon Ratchathani (23.5)
6. Samut Songkhram (23.2)
7. Sukhothai (23.1)
8. Chiang Rai (21.8)
9. Nakhon Sawan (21.8)
10. Udon Thani (21.6)
11. Phitsanulok (20.7)
12. Ayutthaya (20.6)
13. Chon Buri (19.1)
14. Chiang Mai (18.4)
15. Pattaya (18.2)
16. Samut Prakan (18.1)
17. Bangkok (18)
18. Nonthaburi (18)
19. Hua Hin (17.3)
20. Hat Yai (16.2)      

 

Most polluted cities based on data history (Not representative for 2023 but based on data between 2017-2022):

1. Nan (34,1)
2. Chiang Rai (30.6)
3. Khon Kaen (27.6)
4. Korat (27.1)
5. Samut Sakhon (26.8)
6. Chiang Mai (25.6)
7. Nakhon Sawan (22.4)
8. Bangkok (22.4)
9. Ayutthaya (22.1)
10. Hua Hin (18.8)

 

We can clearly see a pattern of pollution in Northern, Central, Eastern and Northeastern Thailand. This becomes even more apparent when looking at data for towns as well. Thailand and Asia in general suffers from a pollution problem that cannot be tackled alone. It has to be a regional effort. But it should also be no excuse for officials to just lay down their arms and do nothing to improve the situation. I hope this can reach and people better understand the data behind all the headlines. As a last point I have one advice for everyone: Please research topics, especially one as important and life affecting as this, so we all can contribute with ideas and not just senseless attacks and blaming. Thank you.

 

https://www.iqair.com/th-en/world-most-polluted-cities?continent=&country=&state=&sort=-rank&page=1&perPage=50&cities=

https://www.who.int/data/gho/data/themes/air-pollution

https://www.pcd.go.th

[KhunLA]

THANKS ... as I may have said one or 10 times ...

... you really don't want to live Hua Hin or above all year long.

 

We're an hour below HH, and amazingly different AQI/PM2.5 #s

Though we still have a good solid 2 months of bad air AQI 75-100 average.

 

Definitely beats 4-6 months of 100+

[Tom H]

Analysis in short:

 

A „star“ behind an IQAir station means: The figure is extrapolated and not based on a sensor. 

 

State providers i.e. in Bangkok „own up“ to 50 stations. These stations have a „sprinkler“ nearby and lower figures for whatever reason:). Not always but many times.

 

Sansiri stations have always lower figures due to their policy or whatever.

 

Some station are not outside located. Schools i.e. 

 

Therefore:

Average figures of a city do not reveal the real situation. 

 

By the way:

International limits for PM2.5 are significant lower (10-20) than the limit of 50 in Thailand.

 

AQI is based on a very complex algorithm of different particles.

NO2 sensors or CO2 sensors missing:). So also here: No detection, no effect.

Therefore AQI not realy exact:)????

 

That means when you have PM2.5 of lets say 100 you are up to 500%  (and higher) over international standards????

 

Pm2.5 blocks the arteries with time….

No matter how old you are.

 

Solution:

Airpurifier and mask outside

 

You cant change the temperature inversion cold-warm-cold from begin of the cold season until the start of the hot season.

 

Teason for seeing people with masks in Bangkok:

 

1. Sun Protection

2. Air Pollution

3. you might have a guess:)

 

 

 

 

 

[JohnNThai]

16 minutes ago, Tom H said:

Analysis in short:

 

A „star“ behind an IQAir station means: The figure is extrapolated and not based on a sensor. 

 

State providers i.e. in Bangkok „own up“ to 50 stations. These stations have a „sprinkler“ nearby and lower figures for whatever reason:). Not always but many times.

 

Sansiri stations have always lower figures due to their policy or whatever.

 

Some station are not outside located. Schools i.e. 

 

Therefore:

Average figures of a city do not reveal the real situation. 

 

By the way:

International limits for PM2.5 are significant lower (10-20) than the limit of 50 in Thailand.

 

AQI is based on a very complex algorithm of different particles.

NO2 sensors or CO2 sensors missing:). So also here: No detection, no effect.

Therefore AQI not realy exact:)????

 

That means when you have PM2.5 of lets say 100 you are up to 500%  (and higher) over international standards????

 

Pm2.5 blocks the arteries with time….

No matter how old you are.

 

Solution:

Airpurifier and mask outside

 

You cant change the temperature inversion cold-warm-cold from begin of the cold season until the start of the hot season.

 

 

 

 

There’s so much that still needs to be done. Standardized sensor placement, complete sensor array as you mentioned and more study into the topic as well. It cannot go on like this. KN95 mask wearing and air purifiers are a must, except for the Deep South I haven’t been anywhere in the rest of Thailand, where I didn’t feel an effect of pollution. What just lead me to this summary is the constant sensationalism and constant ranking of this and that. Who knows how many hundred cities around the world are just as bad or even worse. And if these inaccurate readings already signify something even worse, I really don’t want to know the real values. Instead of blaming and bashing one city or region, we should be working on monitoring all places and put it measures to mitigate as much as we can.

[Tom H]

According to the Geo-informatics and Space Technology Development Agency (GITSDA), 5,572 hotspots were detected in Thailand yesterday, which was a 5-year record high. In the meantime, there were 10,563 hotspots in Myanmar, 9,652 in Laos, 1,342 in Cambodia, 870 in Vietnam and 22 in Malaysia

[JohnNThai]

2 hours ago, Tom H said:

According to the Geo-informatics and Space Technology Development Agency (GITSDA), 5,572 hotspots were detected in Thailand yesterday, which was a 5-year record high. In the meantime, there were 10,563 hotspots in Myanmar, 9,652 in Laos, 1,342 in Cambodia, 870 in Vietnam and 22 in Malaysia

This year is absolutely crazy again. Over 25,000 hotspots in Southeast Asia alone. I’m afraid we won’t see this matter resolved in our lifetime.

[mania]

On 3/25/2023 at 11:34 PM, Tom H said:

Solution:

Airpurifier and mask outside

Sorry but that is not much of a "Solution"

 

Like telling folks starving in a desert the solution is a Sand-wich ????

 

Seriously though it is something each person should really look closely at & decide.

 

Because this kind of health risk is actually optional

(optional maybe not for everyone but many can change their choice to live in such conditions)