From: Hak Hakanson , San Sai,  Chiang Mai

I was wondering why my eyes were burning. While the outside temperature is reasonable, I’ve just closed up the house and turned on the aircon to try to isolate myself from some of the vile soup. Of course, the aircon draws power coming from the generators east of Lampang which burn soft coal, so I am now contributing to the air pollution.

Following the lead from the article which follows, I calculated the PM-10 average for the last 10 days, when the readings suddenly jumped decisively over 100:

PM-10 Levels by date
March 6th 130.9
March 5th 124.3
March 4th 126.3
March 3rd 101.8
March 2nd 191.4
March 1st 170.1
February 28th 116.6
February 27th 118.4
February 26th 120.8
February 25th 105.8


For 25 Feb through 06 Mar, it is 131: well on the way towards the 161.7 average of two years ago. With one day this year already at 191, we’re well on the way to at least matching the 303.9 reading of 14 Mar 2007.

See the following article from 2008:

Air pollution levels in Chiang Mai rising – February 27th, 2008

. . . In London, the United States and the European Union as a whole it is considered a serious pollution ‘episode’ if the PM-10 level exceeds 50 – see the London Air Quality Network website.

For some reason, the Thai Pollution Control Department has set the ’safe level’ to be anything less than a PM-10 of 120. Just to illustrate how high the levels can get to in Chiang Mai, on 14th March 2007 PM-10 levels reached 303.9 – catastrophically high by any standards.

By way of comparison, the World Health Organisation came up with a weighted list of average PM-10 concentrations in residential areas of cities larger than 100,000 throughout the world. A selection of these follows:

Sudan 246
Pakistan 180
Iraq 178
Saudi Arabia 106
Indonesia 102
Syria 102
Myanmar 89
China 87
Thailand 76
Israel 52
Greece 47
Spain 40
United States 25
Malaysia 24
Denmark 23
Germany 22
United Kingdom 19
New Zealand 16
France 15
Sweden 13

I decided to work out the daily average for Chiang Mai over the last year from February 2007 to February 2008 and came up with the following:

Chiang Mai 49.85

I then worked out the daily average for March 2007 only and it worked out as the following:

Chiang Mai 161.7

When is the best time to visit Chiang Mai? The answer would depend on the state of your respiratory system – but I’d say avoid March if possible!

Off hand, I’m wondering why any tourist would want to come here — unless perhaps to catch a view of the temples before they are dissolved by air pollution.

I mentioned my impact on the power plant because:

Egat loses Lampang pollution case By Ekkapong Praditpong
The Nation
Published on March 5, 2009

Chiang Mai – The Chiang Mai Administrative Court yesterday ordered the Electricity Generating Authority of Thailand (Egat) to pay compensation to villagers affected by the pollution caused by its lignite power plant in Lampang’s Mae Moh district.

. . . The court considered the Pollution Control Department’s air-quality report from November 1992 to August 1998 that found the level of ambient sulphurdioxide (SO2) in the area at beyond 1,300 micrograms per cubic meter for 50 out of the 70 months measured.


Compare the SO2 pollution rates here today, 2.1, vs the average monthly rate of 1,300 around the Mae Moe power plant. Those folks reallyhave it tough.