Thailand's Most Polluted Air Is In The North

[sriracha john]

Nation's most polluted air is in the North

Residents of the North are facing a greater risk of lung cancer when compared with locals in other regions, according to statistics.

Currently, more than 40 new lung cancer patients are being diagnosed per 100,000 people in the North each year. In other regions, on average, only 10 such patients were identified among 100,000 locals.

"This means the risk for northern residents is about four times higher," Dr Phongtape Wiwatanadate said yesterday.

Besides teaching at the Chiang Mai University's Faculty of Medicine, Phongtape conducts research on air quality in the Chiang Mai - Lamphun basin.

His research in 2007 checked people's health to determine whether they had symptom that could indicate respiratory problems. The findings showed more than 20 out of 25 people had the symptoms.

Phongtape believed small particulate particles were a problem to Chiang Mai's air quality.

"Their presence affects people's health because many people report having difficulty breathing and coughing," he said.

So far, the amount of particulate particles smaller than 10 microns in Chiang Mai has not exceeded Thai authorities' safety standards from last year.

According to Thai authorities, these dust particles will pose health risks only if their amount is over 120 micrograms per cubic metre of air.

"But in Europe, the safe level means there should be fewer than 50 micrograms per cubic metre of air," Pongthep said.

- The Nation / 2009-01-29

[adjan jb]

Amphur Saraphi has the highest number of lung cancer deaths in the whole country. According to Thai scientists, smoking and indoor radon are the main factors.

[WinnieTheKhwai]

An article just reports. It could be a case of a bullshit Dr. Phongtape instead? Not sure if your issue is really with the article, though a simple web search would have shown that the particulate matter values for Chiang Mai are actually better on average than many other places in Thailand.

Of course the highs in March are sometimes very high, it's possible that this has a bigger impact than having marginally lower averages year-round.

[yumidesign]

Nation's most polluted air is in the North

BANGKOK: -- Residents of the North are facing a greater risk of lung cancer when compared with locals in other regions, according to statistics.

Currently, more than 40 new lungcancer patients are being diagnosed per 100,000 people in the North each year. In other regions, on average only 10 such patients were identified among 100,000 locals.

"This means the risk for northern residents is about four times higher," Dr Phongtape Wiwatanadate said yesterday.

Besides teaching at the Chiang Mai University's Faculty of Medicine, Phongtape conducts research on air quality in the Chiang Mai - Lamphun basin.

His research in 2007 checked people's health to determine whether they had symptom that could indicate respiratory problems. The findings showed more than 20 out of 25 people had the symptoms.

Phongtape believed small particulate particles were a problem to Chiang Mai's air quality.

"Their presence affects people's health because many people report having difficulty breathing and coughing," he said.

So far, the amount of particulate particles smaller than 10 microns in Chiang Mai has not exceeded Thai authorities' safety standards from last year.

According to Thai authorities, these dust particles will pose health risks only if their amount is over 120 micrograms per cubic metre of air.

"But in Europe, the safe level means there should be fewer than 50 micrograms per cubic metre of air," Pongthep said.

-- The Nation 2009-01-29

Pity this research does not give information on when is the worst time of year for this pollution. From February to when it starts raining seams to be the worst time, but last year was not as bad as the year before when you could not see more than 1 k.

Life is indeed dangerous

[patklang]

This isnt new news.

its well known that lung cancer in Chiang Mai is very high compared to the rest of Thaialnd.Thats why i do not live there as its a death trap long term.

[Lobin]

Simply, I think it's a Bullshit article

why is it a bullshit article? because you live here in this 'paradise', so surely nothing could attempt to upset it?

just look or try to look at doi suthep some days, it isnt there! david copperfield couldnt do a better job. the amount of illegal burning that goes on, i am not surprised!

[patklang]

living in fantasy world if you cannot accept the place is very very polluted.I love Chiang Mai but i will speak the truth,unless everybody on news/internet etc are telling big lies and want to stop people living there.

[Lorin]

Why Chiang Mai? Seems to me BKK or Chonburi with all the industry and traffic should be more polluted?

[Maccheroncini]

I can't stand the polluted air everywhere particularly in BKK. In BKK, considering "better air", it's like breathing in toxic steam .

I still like it here.

[uptheos]

Chiangmai is a great place - but there is no doubt it is polluted.

[PlaShadow]

Amphur Saraphi has the highest number of lung cancer deaths in the whole country. According to Thai scientists, smoking and indoor radon are the main factors.

[sabaijai]

Why Chiang Mai? Seems to me BKK or Chonburi with all the industry and traffic should be more polluted?

Agricultural burning and forest fires. The situation is much the same in the provinces of Chiang Rai and Mae Hong Son, which produce suspended particulate matter (SPM) statistics at roughly the same level -- though often worse, in the case of Chiang Rai -- than Chiang Mai each year during the burning season, roughly Feb to April.

I have homes in Bangkok, Chiang Mai and Mae Hong Son. Feb through April the air in Bangkok is usually much better than the air in the north. The rest of the year northern air quality is better. I assume high SPM stats in the north during the burning months tips the scales in Bangkok's favour when factored into at annual figures.

Despite these facts, one can't draw a direct correlation between air quality and lung cancer rates without comparing other factors (eg genetics, tobacco-smoking, presence of other carcinogenics, etc) and without carrying out statistical analyses on reliability and validity of stats used.

SPM is only one factor in what we generally call 'air pollution,' so to conclude that the north has 'the most polluted air' is a bit of a leap. Still, during the burning season I would rather be in Bangkok

[ASHTONITE]

Welcome to THAILAND... a developing country. :-) Try living in BEIJING... MAMBAI... JAKARTA... you will be thankful for air quality in Thailand :-)

[adjan jb]

I have homes in Bangkok, Chiang Mai and Mae Hong Son.

3 homes ?

Have you already calculated your carbon footprint?

http://www.climatecrisis.net/takeaction/carboncalculator/

http://www.carbonfootprint.com/calculator.aspx

[john b good]

Simply, I think it's a Bullshit article

It was only a few years ago that dis-believers (could I would suggest your forefathers) claimed that "the earth was FLAT"

Edited January 29, 2009 by john b good

[Priceless]

Nation's most polluted air is in the North

Residents of the North are facing a greater risk of lung cancer when compared with locals in other regions, according to statistics.

Currently, more than 40 new lung cancer patients are being diagnosed per 100,000 people in the North each year. In other regions, on average, only 10 such patients were identified among 100,000 locals.

"This means the risk for northern residents is about four times higher," Dr Phongtape Wiwatanadate said yesterday.

Besides teaching at the Chiang Mai University's Faculty of Medicine, Phongtape conducts research on air quality in the Chiang Mai - Lamphun basin.

His research in 2007 checked people's health to determine whether they had symptom that could indicate respiratory problems. The findings showed more than 20 out of 25 people had the symptoms.

Phongtape believed small particulate particles were a problem to Chiang Mai's air quality.

"Their presence affects people's health because many people report having difficulty breathing and coughing," he said.

So far, the amount of particulate particles smaller than 10 microns in Chiang Mai has not exceeded Thai authorities' safety standards from last year.

According to Thai authorities, these dust particles will pose health risks only if their amount is over 120 micrograms per cubic metre of air.

"But in Europe, the safe level means there should be fewer than 50 micrograms per cubic metre of air," Pongthep said.

- The Nation / 2009-01-29

My sincere apologies for a long and somewhat complicated post, but I am getting so tired with articles like the one in the OP.

As far as the claimed causal relationship between air pollution and lung cancer this article must, in my opinon, be bullsh*t. Why? Because the air pollution levels in Chiang Mai are, calculated as yearly acerages, actually among the lowest in Thailand. Consider the following graph, showing moving 12-month averages for five locations in Thailand (raw data from the Pollution Control Department (PCD) website http://www.pcd.go.th/AirQuality/Regional/Q...?task=default):

I have chosen to show Samut Prakarn and Sara Buri because they are the two most polluted locations currently measured, Surat Thani because it is the least polluted, and of course Chiang Mai and Lampang because that (i.e. Northern Thailand) is what we are discussing. If air pollution were the only, or even a major, cause of high incidence of lung cancer, one would expect the incidence in Samut Prakarn and Sara Buri to be much higher than in Chiang Mai.

So, how about the infamous Chiang Mai peak in March of most years, couldn't that be the cause? Again no, because unpleasant as it is, at least some years (2007!), it is in no way the highest in Thailand. The following graph shows the seasonal patterns for the same five locations (using data from 2000-2008, except for Samut Prakarn and Sara Buri where measurements didn't start until late in 2003):

Obviously there is a high peak in March for Chiang Mai, but this peak is lower than what the poor people of Samut Prakarn and Sara Buri have to live with from October to March, i.e. for six months of every year!

So, what can then be the cause of the high incidence of lung cancer in Chiang Mai, which seems to be true at least for women? (The male lung cancer incidence is much lower in comparison to other locations, though it is significantly higher than for women in Chiang Mai, according to a research article here http://medicine.plosjournals.org/perlserv/...0185&ct=1):

I recently came across an abstract of a research paper by a number of Japanese and Thai researchers (http://cat.inist.fr/?aModele=afficheN&cpsidt=1212389) published by the Japanese Cancer Society. I will post an excerpt from it:

"Lung cancer incidence among Northern Thai women is one of the highest in Asia (an annual age-adjusted incidence rate of 37.4 per 100,000), and the incidence rate significantly differs by geographical districts. Therefore, we conducted a comparative study of women living in the Sarapee area, which showed the highest (crude incidence rate, 40.9), and the Chom Tong area, which had one of the lowest incidence rates (8.5) in Chiang Mai Province, despite the two areas' geographical and cultural closeness.

[...]

Our results suggest that tobacco (Khiyo) smoking alone may not be able to explain the very high incidence of female lung cancer in Northern Thailand, and that chronic benign respiratory disease, possibly caused by the infection of fungi such as M(icrosporum) canis, is likely to be involved in the etiology of female lung cancer in North Thailand."

I have seen other reports that seem to indicate that frequently high levels of radon in indoor air might be another cause (I have not been able to retrieve those reports in the time available for this post).

One more thing. The pollution levels in Chiang have been improving quite significantly over the last 5-10 years, as can be seen by the following graph:

I wish that people would concentrate on further improving this situation (and of course, in a wider perspective, to improve the situation in Samut Prakarn and Sara Buri) instead of spreading rumours, half-truths and desinformation about Chiang Mai. It is probably wise for people with a pre-existing respiratory condition to try to avoid Chiang Mai during March, but apart from that we live in a lovely city, including from an air pollution perspective!

/ Priceless

PS Concerning Dr Pongthep's last statement about Thai and European air quality standards. The Thai standard is 120 µg/m3, which should never be exceeded. The European standard is 50 µg/m3, which may be exceeded up to 35 times per, i.e. every ~10th day! One would expect a "Dr" to understand the difference between those two concepts, and that they are not comparable.

Edited January 29, 2009 by Priceless

[Pantip]

Thanks 'Priceless'.

I admire your tenacity in trying to convert the pollution complaining mob with the facts. I’m afraid that you have an impossible task trying to educate people who don’t want to learn.

[Priceless]

Thanks 'Priceless'.

I admire your tenacity in trying to convert the pollution complaining mob with the facts. I’m afraid that you have an impossible task trying to educate people who don’t want to learn.

I share your doubts

/ Priceless

[chiang mai]

I for one am beginning to find the bloody mindedness of the "Chiang Mai clean air brigade" offensive. One suspects that any evidence that does not support the Brigade's mantra, regardless of its source, will be considered suspect and ultimately considered incorrect!

[hhper]

I for one am beginning to find the bloody mindedness of the "Chiang Mai clean air brigade" offensive. One suspects that any evidence that does not support the Brigade's mantra, regardless of its source, will be considered suspect and ultimately considered incorrect!

Totally agree. This has been discussed before and some long timers (as always) will argue that as it does not affect them personally, therefore it is not a problem (and that has to be a real joke), and that was at a time when the air quality was a lot worse than what it is now.

I know for sure over the last week that it is affecting me and as the burning season progresses it will get worse.

[ChiangMai2]

Amphur Saraphi has the highest number of lung cancer deaths in the whole country. According to Thai scientists, smoking and indoor radon are the main factors.

What a lovely little map! Did a child do it? So if I live outdoors and don't smoke is it safe to live in Saraphi?

[WaiWai]

Winnie made an interesting point:

the highs in March are sometimes very high, it's possible that this has a bigger impact than having marginally lower averages year-round.

For the benefit of those who didn't know much about radon, either:

Radon is a radioactive gas that is found in the earth's rock and soil. It is formed by the natural breakdown of radium, which is itself a decay product of uranium.

As radon decays, it forms radioactive by-products called either "progeny," "decay products" or "daughters" which, if inhaled, can damage lung tissue and cause lung cancer.

Invisible and odorless, radon is a health hazard when it accumulates to high levels inside homes or other structures. And it is deadly. Indoor radon exposure is estimated to be the second leading cause of lung cancer deaths each year in the United States. Cigarette smoking is responsible for the large majority (87 percent) of lung cancer deaths.

lungusa.org/site/pp.asp?c=dvLUK9O0E&b=35395

I also found:

Doctor Charat Singhkaew, Director of Saraphi hospital in Chiang Mai, revealed the results of a study conducted by Chiang Mai University's Faculty of Medicine, that Saraphi District has the highest number of Thais killed by toxic-dust-induced lung cancer. The cause of the disease is the basin geography and high air pressure, which traps dust particles smaller than 2.5 microns in the area. Moreover, locals unknowingly inhale radon gas emitted from uranium found on and under the ground on which their houses are built.

He warned those living in the area that new houses should be built higher than ground level to allow for ventilation. Also, cracks in cement floors should be filled and windows should be kept open to increase air flow.

thailandoutlook.tv/TOC/PrintNews.aspx?DataID=1006039

[mrmillersr]

Thanks 'Priceless'.

I admire your tenacity in trying to convert the pollution complaining mob with the facts. I’m afraid that you have an impossible task trying to educate people who don’t want to learn.

So I guess you're also against the cigarette complaining mob who also have this wild idea cigarette smoking is harmful.

There are inane posts and then there are real inane posts. Anyone believing the air pollution in Chiang Mai is not a problem and comes out and states it falls in the latter category.

Then again it is probably the pollution affecting their brains that makes them make stupid comments like this.

[femi fan]

just look or try to look at doi suthep some days, it isnt there! david copperfield couldnt do a better job. the amount of illegal burning that goes on, i am not surprised!

Well, this has often confused me. I'm sure the illegal burning goes on at certain times of the year, and that explains why doi suthep is difficult to impossible to see from march time. But here we are over the winter, some days it's clear as anything, the next day it can be very difficult to see. What changes this on a day by day basis? I don't notice huge amounts of wind on one day, then none the next.

Outside of the burning season i just don't really get it why the visibility of doi suthep changes from day to day, while blue skies abound.

Anyone know why?

[femi fan]

Another thing that i can't work out either is that if 40 give or take a few people out of 100,000 people contract lung cancer, how can researchers and other people call this pollution 'deadly'? It's not exactly a lot of people now is it?!

And if radon is so abundant i saraphi, then why isn't everybody getting lung cancer? Why only a tiny fraction of those living here?

[meadish_sweetball]

And if radon is so abundant i saraphi, then why isn't everybody getting lung cancer? Why only a tiny fraction of those living here?

I don't know anything about the claims of radon in Saraphi except for what has been posted here.

But -

Not everybody who smokes tobacco regularly develops lung cancer; still it has been firmly established that tobacco smoking significantly elevates the risk for lung cancer.

Not everybody who drives drunk gets into a car accident, but when you look at accident statistics, people who have been drinking are over-represented among those involved in car accidents.

So provided that there really are unusually high levels of radon in Saraphi (which I don't know), nobody ever said that all other factors are equal for the people who live in Saraphi. And these factors make a difference, too.

Genetic predisposition for lung cancer, diet, exercise level, exact location of house in Saraphi and time spent/activities there (some houses within Saraphi will have more radon leaks than others, and radon works "best" in enclosed spaces and on the first floor of a house so a person who lives in a one story house with conditions more conducive to radon leaks will contract more radon particles), profession, tobacco smoking etc. are all factors to consider as well.

So just where one lives is not the end-all and be-all of it all.

Well, this has often confused me. I'm sure the illegal burning goes on at certain times of the year, and that explains why doi suthep is difficult to impossible to see from march time. But here we are over the winter, some days it's clear as anything, the next day it can be very difficult to see. What changes this on a day by day basis? I don't notice huge amounts of wind on one day, then none the next.

Outside of the burning season i just don't really get it why the visibility of doi suthep changes from day to day, while blue skies abound.

Not all the haze we see is due to burning or traffic. Some of it is fog/mist.

[Priceless]

Thanks 'Priceless'.

I admire your tenacity in trying to convert the pollution complaining mob with the facts. I’m afraid that you have an impossible task trying to educate people who don’t want to learn.

So I guess you're also against the cigarette complaining mob who also have this wild idea cigarette smoking is harmful.

There are inane posts and then there are real inane posts. Anyone believing the air pollution in Chiang Mai is not a problem and comes out and states it falls in the latter category.

Then again it is probably the pollution affecting their brains that makes them make stupid comments like this.

I am not going to fall into the name-calling trap, I'll just try to explain this thing in very easy-to-understand terms.

Chiang Mai has among the lowest levels of air pollution (PM<10) of all the locations measured by the Pollution Control Department.

If the incidence of respiratory disease is indeed (much?) higher in Chiang Mai, then this cannot logically be caused by the air pollution. If air pollution were the (or a major) cause of respiratory disease, then higher pollution levels would cause higher incidences of these diseases.

This is not a matter of opinion but rather a case of logical reasoning. In statistics this relationship is called "correlation". If there is no correlation, then one can safely assume that there is no (or an extremely weak) causal relationship.

/ Priceless

[Priceless]

Thanks 'Priceless'.

I admire your tenacity in trying to convert the pollution complaining mob with the facts. I’m afraid that you have an impossible task trying to educate people who don’t want to learn.

So I guess you're also against the cigarette complaining mob who also have this wild idea cigarette smoking is harmful.

There are inane posts and then there are real inane posts. Anyone believing the air pollution in Chiang Mai is not a problem and comes out and states it falls in the latter category.

Then again it is probably the pollution affecting their brains that makes them make stupid comments like this.

I am not going to fall into the name-calling trap, I'll just try to explain this thing in very easy-to-understand terms.

Chiang Mai has among the lowest levels of air pollution (PM<10) of all the locations measured by the Pollution Control Department.

If the incidence of respiratory disease is indeed (much?) higher in Chiang Mai, then this cannot logically be caused by the air pollution. If air pollution were the (or a major) cause of respiratory disease, then higher pollution levels would cause higher incidences of these diseases.

This is not a matter of opinion but rather a case of logical reasoning. In statistics this relationship is called "correlation". If there is no correlation, then one can safely assume that there is no (or an extremely weak) causal relationship.

/ Priceless

I think that your make things way way to technical. The fact remains, that I can tell by looking at Doi Sutep how much pollution is in the air, by using my memory of what clear days look like. If you want to go ahead and believe the numbers and all the data thats fine, but my logic tells me when its best not to be outdoors too much, and when its ok. I also relay on a highly technical device called MY NOSE, and first thing in the morning step out onto my terrace and take a rather large sample reading, and within nano seconds I am givin a recommendation with regards to the level of air pollution.

About there being mist/fog, well, thats a load of drizzel, as there is NO FOG at noon in the blazing sun. This is CM, not Doi Internon.

To not be able to see the connection between many months of air pollution and long term lung cancer, is akin to not being able to see the forrest through the trees.

What you are saying is that your nose and eyes are better measuring apparatuses than the equipment that the Pollution Control Department is using. Congratulations, you have a career as pollution measurer in front of you. I'm sure that the PCD will be willing to pay really well, since the "old-fashioned" equipment is quite expensive to acquire and operate

More seriously, I believe that one of the problems with this discussion is that many people confuse visibility (or rather opacity) with air pollution. At least they believe that the degree of opacity is directly proportional to the level of pollution. I am however convinced (I am not an expert in optics) that the opacity is a function of not only the level of pollution but also of the composition of the polluting matter. Maybe someone with more insight into physics and optics could explain what different sizes of particulate matter, different optical properties of the individual particles etc would have on the perceived opacity.

Anyways, it is clear that a number of posters here subscribe to the conspiracy theory that the PCD is systematically falsifying the data published on their website. I don't, if for no other reason than that I don't believe they have the sophistication to falsify long series of daily data.

There is frequent talk of the Chinese authorities falsifying pollution data, in particular in connection with last year's Olympic Games. As far as I've been able to determine, the Chinese never published any daily data though, only computed averages over longer periods such as months. These kind of data are much easier to "edit".

/ Priceless

[Mapguy]

Thanks 'Priceless'.

I admire your tenacity in trying to convert the pollution complaining mob with the facts. I'm afraid that you have an impossible task trying to educate people who don't want to learn.

So I guess you're also against the cigarette complaining mob who also have this wild idea cigarette smoking is harmful.

There are inane posts and then there are real inane posts. Anyone believing the air pollution in Chiang Mai is not a problem and comes out and states it falls in the latter category.

Then again it is probably the pollution affecting their brains that makes them make stupid comments like this.

I am not going to fall into the name-calling trap, I'll just try to explain this thing in very easy-to-understand terms.

Chiang Mai has among the lowest levels of air pollution (PM<10) of all the locations measured by the Pollution Control Department.

If the incidence of respiratory disease is indeed (much?) higher in Chiang Mai, then this cannot logically be caused by the air pollution. If air pollution were the (or a major) cause of respiratory disease, then higher pollution levels would cause higher incidences of these diseases.

This is not a matter of opinion but rather a case of logical reasoning. In statistics this relationship is called "correlation". If there is no correlation, then one can safely assume that there is no (or an extremely weak) causal relationship.

/ Priceless

Priceless, I really do very much appreciate and admire what you often contribute to this ongoing (perhaps, boring to some, conversation), but I do think that your overall arguments, while sound in their fashion, are lacking some of the time. As well, I think your own "logical thinking," as you have presented it, is very flawed, but that's hard to explain. I think you are sometimes more than a tad arch in your "pronunciomentos!"

Regarding the news article in The Nation, frankly, if I were to subscribe to it, I would use it to line the cat boxes we keep handy at home for the resident felines except that the newsprint might be hazardous to their health. However, that article is neither more nor less than found in a typical Murdoch publication, often including articles even in the Times. I suggest the CMU researcher himself also is embarrassed.

Nonetheless, I would hope that such articles would indeed continue to be published. Within them, from time to time, there might be a clue to look further --- unless you don't want to look. A "toss-off" article in The Nation by itself doesn't add up to much.

Priceless, your lectures illustrated with graphs are woefully incomplete and regrettably misleading to too many. I don't think that you can be expected to present complete arguments here, but it's the misleading (appearance of truth through graphs!!) aspect that distresses me quite a lot. I don't think that Burroughs (the manufacturer of calculating machines that descriptive statisticians and researchers used before computers were generally available) guaranteed truth. Nor do Dell or Apple. Or--- more to the point --- SPSS (Statistical Package for the Social Sciences), or whatever statistical package you prefer to use.

The bottom line, friends --- to keep it short here --- is that there is a problem with air pollution specific to this area for various reasons too much to get into in this post. Comparatively, as Priceless has pointed out, there are indeed better places to live (seasonally, especially) in Thailand. But if you like people more than calculators, then you will appreciate that not all people are able to "winter" here and "summer" there when the pollution is better or worse. And I do hope that people appreciate that subjective opinions about air pollution are not always "delusional" or "paranoid," two descriptions that Priceless once suggested in an array of nasty adjectives in his dismay of those who offered more than "facts" one can graph. I do, however, agree that some folks go absolutely bonkers with hyperbole.

Now, this might seem to some a "flame." It isn't. I'll say it again. It isn't. But don't just look at the graphs. When you do, understand that they are created from the best available data. In the case of Chiang Mai, there are more PCD data than in most places in Thailand to help give you a picture of what's going on with air pollution --- but, folks, to quote myself (sorry!) --- the traffic police don't wear face masks because they are worried about chapped lips. And, you folks who think haze on Doi Suthep is some kind of harmless water vapor, have I got news for you! Later!!

Cheers!

[dinthailand]

Thanks 'Priceless'.

I admire your tenacity in trying to convert the pollution complaining mob with the facts. I'm afraid that you have an impossible task trying to educate people who don't want to learn.

So I guess you're also against the cigarette complaining mob who also have this wild idea cigarette smoking is harmful.

There are inane posts and then there are real inane posts. Anyone believing the air pollution in Chiang Mai is not a problem and comes out and states it falls in the latter category.

Then again it is probably the pollution affecting their brains that makes them make stupid comments like this.

I am not going to fall into the name-calling trap, I'll just try to explain this thing in very easy-to-understand terms.

Chiang Mai has among the lowest levels of air pollution (PM<10) of all the locations measured by the Pollution Control Department.

If the incidence of respiratory disease is indeed (much?) higher in Chiang Mai, then this cannot logically be caused by the air pollution. If air pollution were the (or a major) cause of respiratory disease, then higher pollution levels would cause higher incidences of these diseases.

This is not a matter of opinion but rather a case of logical reasoning. In statistics this relationship is called "correlation". If there is no correlation, then one can safely assume that there is no (or an extremely weak) causal relationship.

/ Priceless

I think that your make things way way to technical. The fact remains, that I can tell by looking at Doi Sutep how much pollution is in the air, by using my memory of what clear days look like. If you want to go ahead and believe the numbers and all the data thats fine, but my logic tells me when its best not to be outdoors too much, and when its ok. I also relay on a highly technical device called MY NOSE, and first thing in the morning step out onto my terrace and take a rather large sample reading, and within nano seconds I am givin a recommendation with regards to the level of air pollution.

About there being mist/fog, well, thats a load of drizzel, as there is NO FOG at noon in the blazing sun. This is CM, not Doi Internon.

To not be able to see the connection between many months of air pollution and long term lung cancer, is akin to not being able to see the forrest through the trees.

What you are saying is that your nose and eyes are better measuring apparatuses than the equipment that the Pollution Control Department is using. Congratulations, you have a career as pollution measurer in front of you. I'm sure that the PCD will be willing to pay really well, since the "old-fashioned" equipment is quite expensive to acquire and operate

More seriously, I believe that one of the problems with this discussion is that many people confuse visibility (or rather opacity) with air pollution. At least they believe that the degree of opacity is directly proportional to the level of pollution. I am however convinced (I am not an expert in optics) that the opacity is a function of not only the level of pollution but also of the composition of the polluting matter. Maybe someone with more insight into physics and optics could explain what different sizes of particulate matter, different optical properties of the individual particles etc would have on the perceived opacity.

Anyways, it is clear that a number of posters here subscribe to the conspiracy theory that the PCD is systematically falsifying the data published on their website. I don't, if for no other reason than that I don't believe they have the sophistication to falsify long series of daily data.

There is frequent talk of the Chinese authorities falsifying pollution data, in particular in connection with last year's Olympic Games. As far as I've been able to determine, the Chinese never published any daily data though, only computed averages over longer periods such as months. These kind of data are much easier to "edit".

/ Priceless

Not necessarily falsifying data, just, well, this is Thailand yeah, and I have seen quality control here, so....

And yes, either right or wrong, I judge the level of pollution by the visibility. Cause if the visibility is reduced, it IS related to the amount of matter that is in the air. Same goes with a glass of murky water. I do not think one needs to be schooled in physics or optics to understand this relationship. Once again, I feel that you complicate matters to a high degree.

If I can see that the air is smoky from my terrace to the mountain, than that is all the data I need to come to a conclusion. So yes, MY eyes and nose are better measuring apparatuses as I and only I will determine what is an acceptable level of pollution for ME, be it noise, sound, air or what ever. No one is going to convince me that there air is fresh and ok, when I know it is not, does not matter what data they have or what equipment they used to get it.