Smoke, Smog, Dust 2012 Chiang Mai

[Priceless]

I have to agree with EJ, it's getting very hard to understand what should be believed in this matter.

I never thought that the numbers comming out of two solitary monitoring stations for all of CM in 2007 represented the true pollution picture. Today I see the green smiley face on the pollution display screen opposite the Governers Mansion telling me that everything is OK, along with some silly low number - I definitely don't believe that.

The graphs we've seen displayed here so many times over the years: with all due respect to Priceless for his effort and his intellect, I don't think they tell the complete unabridged story, the graphs may be an accurate representation of the numbers input to them but the validty and completness of those numbers remains suspect, in my mind. I think I'm to the point like many others here where the only thing I fully trust is the line of sight from my eigth floor window, the tenderness of my throat and the degree to which my eyes are watering, anecdotal indeed but reliable and accurate, certainly.

I happen to believe that most of the time the numbers coming out of the two measuring stations represent the true picture. However, they certainly do not represent the complete picture, in particular and obviously not for all of Chiang Mai province.

Furthermore, I think the posters that are looking at the hourly numbers posted by the PCD should consider the difference between an hourly number and a 24-hour average, which is all we had access to until 1 February of this year. There just might be a reason why all national/regional standards, that I have so far seen, are defined in terms of 24-hour averages (while the standards for several other pollutants are defined as hourly values).

As for anecdotal evidence, I am willing to trust it under the following two conditions:

1/ That there is largely a consensus among the anecdotes.

2/ That there is no objective factual evidence that contradicts the anecdotes.

We have certainly gone (are going?) through a very bad spell recently, and I feel very sorry for e.g. asthmatics who must have been suffering unbearably. I am in no way denying this, but I do mind the "dumbing down" of the discussion caused by denying the only factual evidence that we have.

/ Priceless

PS For those who believe that their experiences of bad visibility, sore throats and irritated eyes are more (or equally) valid and trustworthy as the PCD's measurements, I would like to recommend the book "The believing brain" by the American neuropsychologist Michael Shermer (Times Books, 2011).

[Mapguy]

I have to agree with EJ, it's getting very hard to understand what should be believed in this matter.

Today I see the green smiley face on the pollution display screen opposite the Governers Mansion telling me that everything is OK, along with some silly low number - I definitely don't believe that.

The graphs we've seen displayed here so many times over the years: with all due respect to Priceless for his effort and his intellect, I don't think they tell the complete unabridged story, the graphs may be an accurate representation of the numbers input to them but the validty and completness of those numbers remains suspect, in my mind. I think I'm to the point like many others here where the only thing I fully trust is the line of sight from my eigth floor window, the tenderness of my throat and the degree to which my eyes are watering, anecdotal indeed but reliable and accurate, certainly.

There are only two stations in the province. Neither represents the "full picture. What you get from Priceless' assiduous number crunching is indeed corroborative evidence to what your nose knows and, probably, a reasonable indication of historical trends. But it is over-crunched data.

The greatest weakness to the numbers is the paucity of data points, but you have to go with the best available data, and --- mechanical failure from time to time aside --- there is no need to suspect a conspiracy to squash the numbers.

PCD is working to improve its reporting, but there is a long way to go. But to say the readings are no good and suggesting there is some sort of TAT conspiracy to lower the counts is just cheap conspiracy thinking. TAT and the local chamber of commerce certainly don't like the rotten publicity. No doubt about it. If there is some effort to squash the bad publicity on tourist sites, such as TripAdvisor, I wouldn't be surprised.

Regarding a comment of unnamed local physician about not trusting the numbers (We've heard that one before), that is true, certainly depending upon where you live, but to say PCD is massaging the data is an unsupported conclusion.

[chiang mai]

I for one am not suggesting a TAT conspiracy, I do not however dismiss the notion that the data is incomplete and very possibly not reliable, that's all.

[el jefe]

I was out on the 1269/Samoeng Rd both yesterday and this morning. The villagers must have believed the forecast of rain. Yesterday and last night was a big day for burning. There were plenty of still smoldering leaf and garbage piles, agricultural fires, and a lots of roadside clearings.

Why do the Burmese have to travel hundreds of kilometers to set fires in CM??

The air did seem a little less polluted in some areas and I didn't get north of City Hall. Was the air really that clean up there? The current reading meets the EU standard at 44.

A single day or a single reading cannot meet, or fail, the EU standard. You misunderstand the standard, even though people have explained it in this topic several times.

Either way I'm happy with the clearer air. Went back to opening the windows.

I really don't understand the cheap shot at the Burmese. Those practicing traditional agriculture come from all sorts of ethnic roots. But maybe EJ is of La'Na stock and not forgiving yet of the last invasion of Chiang Mai. It was more than a little while ago! There aren't many Burmese among the recent refugee "invasion," actually, and they haven't arrived on armoured elephants! It seems they are mostly taken advantage of.

I interpreted it as a dig at the Thais for blaming all the smog on the Burmese. ie the burning in Burma is the cause, 'cos there's "no burning in Thailand" ;-)

But I could be wrong.....

You are, of course, correct, Mr Smith.

I've heard from dozens of Thais that the pollutionis caused by the burning in Burma. The govt says it, the police say it, the newspapers say it. It's a great way to save face, but until the govt comes out and says that Thais need to take responsibility and stop adding to the problem, there will not be any change.

[MESmith]

You are, of course, correct, Mr Smith.

I've heard from dozens of Thais that the pollutionis caused by the burning in Burma. The govt says it, the police say it, the newspapers say it. It's a great way to save face, but until the govt comes out and says that Thais need to take responsibility and stop adding to the problem, there will not be any change.

Even my wife said it. ME had a major row.....

[el jefe]

I have to agree with EJ, it's getting very hard to understand what should be believed in this matter.

Today I see the green smiley face on the pollution display screen opposite the Governers Mansion telling me that everything is OK, along with some silly low number - I definitely don't believe that.

The graphs we've seen displayed here so many times over the years: with all due respect to Priceless for his effort and his intellect, I don't think they tell the complete unabridged story, the graphs may be an accurate representation of the numbers input to them but the validty and completness of those numbers remains suspect, in my mind. I think I'm to the point like many others here where the only thing I fully trust is the line of sight from my eigth floor window, the tenderness of my throat and the degree to which my eyes are watering, anecdotal indeed but reliable and accurate, certainly.

There are only two stations in the province. Neither represents the "full picture. What you get from Priceless' assiduous number crunching is indeed corroborative evidence to what your nose knows and, probably, a reasonable indication of historical trends. But it is over-crunched data.

The greatest weakness to the numbers is the paucity of data points, but you have to go with the best available data, and --- mechanical failure from time to time aside --- there is no need to suspect a conspiracy to squash the numbers.

PCD is working to improve its reporting, but there is a long way to go. But to say the readings are no good and suggesting there is some sort of TAT conspiracy to lower the counts is just cheap conspiracy thinking. TAT and the local chamber of commerce certainly don't like the rotten publicity. No doubt about it. If there is some effort to squash the bad publicity on tourist sites, such as TripAdvisor, I wouldn't be surprised.

Regarding a comment of unnamed local physician about not trusting the numbers (We've heard that one before), that is true, certainly depending upon where you live, but to say PCD is massaging the data is an unsupported conclusion.

I too have the utmost respect for Priceless's work and have defended it in the past. But we all know that the PCD statistics "missed" a few days when the PM10 was about the 200 level. There have also been several days where they apparently averaged in some hourly zeros when the system wasn't working to come up with some amazingly low numbers. the burning yesterday and last night in Thung Kong and Nam Som was horrendous. But it's far from the measuring stations. But I refuse to believe that the current reading of 25 (last seen on a regular basis in Sept maybe?) is correct. Is it a conspiracy? I'd like to think not. Mechanical failure? Hopefully. But in any case, statistical comparison between this year and prior years is no longer valid. Nor will comparisons with future years be meaningful. Think about it this way -- According to the current reading, the air quality will not get significantly better even if it rains, for days on end.

[Mapguy]

I have to agree with EJ, it's getting very hard to understand what should be believed in this matter.

Today I see the green smiley face on the pollution display screen opposite the Governers Mansion telling me that everything is OK, along with some silly low number - I definitely don't believe that.

The graphs we've seen displayed here so many times over the years: with all due respect to Priceless for his effort and his intellect, I don't think they tell the complete unabridged story, the graphs may be an accurate representation of the numbers input to them but the validty and completness of those numbers remains suspect, in my mind. I think I'm to the point like many others here where the only thing I fully trust is the line of sight from my eigth floor window, the tenderness of my throat and the degree to which my eyes are watering, anecdotal indeed but reliable and accurate, certainly.

There are only two stations in the province. Neither represents the "full picture. What you get from Priceless' assiduous number crunching is indeed corroborative evidence to what your nose knows and, probably, a reasonable indication of historical trends. But it is over-crunched data.

The greatest weakness to the numbers is the paucity of data points, but you have to go with the best available data, and --- mechanical failure from time to time aside --- there is no need to suspect a conspiracy to squash the numbers.

PCD is working to improve its reporting, but there is a long way to go. But to say the readings are no good and suggesting there is some sort of TAT conspiracy to lower the counts is just cheap conspiracy thinking. TAT and the local chamber of commerce certainly don't like the rotten publicity. No doubt about it. If there is some effort to squash the bad publicity on tourist sites, such as TripAdvisor, I wouldn't be surprised.

Regarding a comment of unnamed local physician about not trusting the numbers (We've heard that one before), that is true, certainly depending upon where you live, but to say PCD is massaging the data is an unsupported conclusion.

I too have the utmost respect for Priceless's work and have defended it in the past. But we all know that the PCD statistics "missed" a few days when the PM10 was about the 200 level. There have also been several days where they apparently averaged in some hourly zeros when the system wasn't working to come up with some amazingly low numbers. the burning yesterday and last night in Thung Kong and Nam Som was horrendous. But it's far from the measuring stations. But I refuse to believe that the current reading of 25 (last seen on a regular basis in Sept maybe?) is correct. Is it a conspiracy? I'd like to think not. Mechanical failure? Hopefully. But in any case, statistical comparison between this year and prior years is no longer valid. Nor will comparisons with future years be meaningful. Think about it this way -- According to the current reading, the air quality will not get significantly better even if it rains, for days on end.

My apologies, EJ. Your clarification is appreciated re the Burmese comment.. And I agree with you except many Thais know better and do not indulge in "saving face" Myanmar-bashing. So no cheap shot deserved there, either, in my view! Anyway, does that sort of thinking help solve anything?

Solutions are ultimately local because local circumstances are different. Not easy; not at all easy, worldwide, internationally, regionally, nationally, or locally. Anyway, saving face is not a singularly Thai cultural trait!

Regarding the numbers, I suggest you do not fall into a similar trap as Priceless. He has a very serious problem, in my view, with the paucity of data and too much reliance upon them. A "conspiracy theory" about official massaging of numbers, in my view, is not warranted either. Occasionally P gets off on an unnecessary tangent --- so do we all --- but he has revealed over a few years very genuine concern with real consequences on the ground; he is not a number cruncher all the time! You have to take the numbers for what they are worth. Just to be practical, right now, I have some suspicion that PCD is still breaking in their new web site and the data feed. Their timing to make a change hasn't been opportune!

We can play around with numbers or speculate all we want. It's a forum. I just hope that what shows up here is not just a lot of idle mental masturbation. There are some smart people around.

So, not that I have a lot of grand ideas or solutions, what can we, as individuals, certainly almost all foreigners, actually do? In the several years that I have been following this discussion I have yet to see much suggested, or much done.

[WinnieTheKhwai]

@ElJefe:

Only one station had trouble a couple days. Just fill in data for the other Chiang Mai station. Or do all year on year comparisons against that station.

As much as people like a perfect world, you don't stop doing analysis that spans close to a decade because you miss 3 days (easily substituted).

Besides, there have been outages in the past; again that doesn't (and shouldn't) stop analysis.

Separate point: today we see again what an enormous effect the weather has. Everyone seems in agreement that burning hasn't lessened, yet the situation has markedly improved both from measurements and plain visual observations.

Edited March 11, 2012 by WinnieTheKhwai

[brianmarinus]

http://firefly.geog.umd.edu:8080/firemap/?x=99.30937499999999&y=18.009375000000005&z=7&g=g&v=1&r=5&i=er&l=ad%2Cct

[Maestro]

Interesting map, brianmarinus, showing the fires on the entire planet. It will be interesting to follow how the number of fires in the North of Thailand will -- hopefully -- decrease in the coming days and weeks. It must be quite bad at the moment, considering that the government thinks of evacuating children and old people from that area, as reported here: http://www.thaivisa....-north-worsens/

[Throatwobbler]

I don't understand why it fluctuates so much during the day. Where does the haze go in the afternoon? With the old system this was never very obvious as it only reported averages; I did notice in past years that the afternoons seemed clearer than mornings, but I suspected it was just because of the position of the sun, allowing me to see the mountain clearer in the afternoon. That is not the case.

(I do know the fluctuations aren't caused by fires in the immediate area; there just isn't a correlation with local fires, including forest fires)

I can't claim to know the answer, just a guess:

When the air starts cooling in the afternoon, the ground stays hot for longer. This causes the air near the ground to be warmer than that slightly higher up. As a consequence the lower air rises, taking part of the pollution with it.

Any takers?

/ Priceless

My guess is to to do with the angle of the light. Early morning the sun is coming at a very shallow angle. Midday and early afternoon it is coming from overhead. At miday look straight up and the sky seems pretty clear. Look at the horizon and it's grey.

So early morning all the light is coming at us through the shallow angle making everything look worse.

Edited March 11, 2012 by Throatwobbler

[CMX]

Separate point: today we see again what an enormous effect the weather has. Everyone seems in agreement that burning hasn't lessened, yet the situation has markedly improved both from measurements and plain visual observations.

Yes, just now -

Wind, albeit gentle, from the north = cooler nights and more smoke.

Wind, albeit gentle, from the south = warming nights and less smoke, as there are many fewer fires in that direction.

Not even rain need be involved.

[chiangmaiexpat]

Granted, the air has improved during the last two days, but I am quite surprised at the PCD readings. The last two days have shown PM10 readings in the 40s and 20s at the two Chiang Mai stations and according to the raw data, there was a drastic drop during a period of 6 hours Saturday afternoon. I'd expect these readings for a clear day in the Swiss Alps, or on the ocean shore, but that's not what Chiang Mai currently feels like. Well, perhaps it's just my subjective experience...

Cheers, CMExpat

[chiang mai]

Granted, the air has improved during the last two days, but I am quite surprised at the PCD readings. The last two days have shown PM10 readings in the 40s and 20s at the two Chiang Mai stations and according to the raw data, there was a drastic drop during a period of 6 hours Saturday afternoon. I'd expect these readings for a clear day in the Swiss Alps, or on the ocean shore, but that's not what Chiang Mai currently feels like. Well, perhaps it's just my subjective experience...

Cheers, CMExpat

When I wrote earlier that I didn't trust/believe the data 100% it's because, in part, of anecdotal evidence such as this that require further explanation/analysis.

[chiangmaiexpat]

The data from stations in different northern cities show the same trend. Lampang shows a drop over a 6-hour period in the late Saturday morning, Chiang Mai shows a similar drop during the early afternoon and Chiang Rai shows a drop during the evening. This is consistent with a storm moving from south to north, and with our observation of stormy weather on Saturday and warmer nights since then. If the data was engineered, painstaking effeort would have been expended to make it look consistent, which is quite atypical for Thailand. In view of Occam's razor, I would therefore dismiss any conspiracy theories, and ascribe the strange feeling to the lingering effects of the assault on our respiratory systems during the last weeks.

Cheers, CMExpat

[chiang mai]

The data from stations in different northern cities show the same trend. Lampang shows a drop over a 6-hour period in the late Saturday morning, Chiang Mai shows a similar drop during the early afternoon and Chiang Rai shows a drop during the evening. This is consistent with a storm moving from south to north, and with our observation of stormy weather on Saturday and warmer nights since then. If the data was engineered, painstaking effeort would have been expended to make it look consistent, which is quite atypical for Thailand. In view of Occam's razor, I would therefore dismiss any conspiracy theories, and ascribe the strange feeling to the lingering effects of the assault on our respiratory systems during the last weeks.

Cheers, CMExpat

So perhaps this is the Alps then

BTW, there's no conspiracy theories involved here, just trying to understand more completely the associated events et al.

[Gonzo the Face]

Good friend of mine sent me this pic taken on the 9th Mar. No filter, no touch up.....

Sure seems to be a lot of junk floating around in the air..

What was that about ' Red Moon Arising '

G

Edited March 12, 2012 by Gonzo the Face

[Priceless]

I too have the utmost respect for Priceless's work and have defended it in the past. But we all know that the PCD statistics "missed" a few days when the PM10 was about the 200 level. There have also been several days where they apparently averaged in some hourly zeros when the system wasn't working to come up with some amazingly low numbers. the burning yesterday and last night in Thung Kong and Nam Som was horrendous. But it's far from the measuring stations. But I refuse to believe that the current reading of 25 (last seen on a regular basis in Sept maybe?) is correct. Is it a conspiracy? I'd like to think not. Mechanical failure? Hopefully. But in any case, statistical comparison between this year and prior years is no longer valid. Nor will comparisons with future years be meaningful. Think about it this way -- According to the current reading, the air quality will not get significantly better even if it rains, for days on end.

'the current reading of 25 (last seen on a regular basis in Sept maybe?)'

This is a case of apples and oranges. The reading of 25 is an hourly reading. Alll readings up to and including January of this year are 24-hour averages. These different kinds of readings cannot and should not be compared.

Incidentally, the last time we had a 24-hour average reading of 25 or below (24.3 to be exact) was on 26 November and since then we've had readings of 26.3 and 27.7 during the second half of January.

/ Priceless

[Mapguy]

Why not?

[WinnieTheKhwai]

I too have the utmost respect for Priceless's work and have defended it in the past. But we all know that the PCD statistics "missed" a few days when the PM10 was about the 200 level. There have also been several days where they apparently averaged in some hourly zeros when the system wasn't working to come up with some amazingly low numbers. the burning yesterday and last night in Thung Kong and Nam Som was horrendous. But it's far from the measuring stations. But I refuse to believe that the current reading of 25 (last seen on a regular basis in Sept maybe?) is correct. Is it a conspiracy? I'd like to think not. Mechanical failure? Hopefully. But in any case, statistical comparison between this year and prior years is no longer valid. Nor will comparisons with future years be meaningful. Think about it this way -- According to the current reading, the air quality will not get significantly better even if it rains, for days on end.

'the current reading of 25 (last seen on a regular basis in Sept maybe?)'

This is a case of apples and oranges. The reading of 25 is an hourly reading. Alll readings up to and including January of this year are 24-hour averages. These different kinds of readings cannot and should not be compared.

Incidentally, the last time we had a 24-hour average reading of 25 or below (24.3 to be exact) was on 26 November and since then we've had readings of 26.3 and 27.7 during the second half of January.

/ Priceless

Yes; obviously. I can't believe how hard it is for so many people to get the basics straight.

And it seems they need reminding every week.

[KireB]

Numbers and statistics are just that! Have a look at the horizon, take a deep breath, go jogging for 20 minutes, look at the moon and sun, and you have your own data, perceived data that is. The pollution is still here, maybe less, but the burning will go on!

[CobraSnakeNecktie]

would be interesting to just see the effect on human health with hospital admissions or immune system tracking etc. The PM readings are a just a rough measure of factors affecting health.

Would be most interesting to see actual changes in human health.

I bugged out for california a few weeks ago. I think Jefe is just being crushed by air quality. If your an athlete out breathing that stuff then it really hits hard. If your a couch surfer then really much less of an issue.

Hope if rains for you guys soon.

I am hitting great rides in southern california. I have had it with Feb and March in CM. Great timet to get away. The other months are great however.

[WinnieTheKhwai]

Numbers and statistics are just that! Have a look at the horizon, take a deep breath, go jogging for 20 minutes, look at the moon and sun, and you have your own data, perceived data that is.

You have that all backwards.

It's so obvious that it's really tiresome to point out; my respect for Priceless to manage this still after all these years is sky-high.

But anyway, just once: you have the data to make decisions BEFORE you go jogging for 20 minutes. One look at the readings in the morning should tell you if going for a jog is a good idea or not. It will tell you if it's a good idea even to go out with young kids, or that it's better to stay indoors.

And finally, the numbers help build year-on-year statistics that will allow monitoring of the situation, building understanding of influences that affect the air, and assessing effectiveness of actions (if any) taken.

The pollution is still here, maybe less, but the burning will go on!

Obviously. Guess what, there is burning year round. But the specific weather and atmospheric conditions in late Feb and March keeps the crap hanging around. That's why you saw the sudden sharp decrease over the weekend; it's not like everybody suddenly decided to stop burning.

Since it can be very accurately predicted, at least the basics are in place to enforce burning bans at the right time if the political will is there. (Big 'if', yes.)

[el jefe]

I too have the utmost respect for Priceless's work and have defended it in the past. But we all know that the PCD statistics "missed" a few days when the PM10 was about the 200 level. There have also been several days where they apparently averaged in some hourly zeros when the system wasn't working to come up with some amazingly low numbers. the burning yesterday and last night in Thung Kong and Nam Som was horrendous. But it's far from the measuring stations. But I refuse to believe that the current reading of 25 (last seen on a regular basis in Sept maybe?) is correct. Is it a conspiracy? I'd like to think not. Mechanical failure? Hopefully. But in any case, statistical comparison between this year and prior years is no longer valid. Nor will comparisons with future years be meaningful. Think about it this way -- According to the current reading, the air quality will not get significantly better even if it rains, for days on end.

'the current reading of 25 (last seen on a regular basis in Sept maybe?)'

This is a case of apples and oranges. The reading of 25 is an hourly reading. Alll readings up to and including January of this year are 24-hour averages. These different kinds of readings cannot and should not be compared.

Incidentally, the last time we had a 24-hour average reading of 25 or below (24.3 to be exact) was on 26 November and since then we've had readings of 26.3 and 27.7 during the second half of January.

/ Priceless

Yes; obviously. I can't believe how hard it is for so many people to get the basics straight.

And it seems they need reminding every week.

It may not always be a totally fair comparison to use the hourly reading to the 24 hour hour average, but if I look up at Doi suthep 2-3 kms away and can barely make out the outline of the mountain, yet the current hourly reading is 25, I know something is wrong.

The Nation reported last week that the PCD said CM had 6 consecutive days of PM10 over the 120 limit (I understand the difference between various govt's limits). In an earlier post you said there were 3 days where there were no readings. Coincidentally, those 3 days immediately preceded the 6. The PCD obviously thinks that the zeros are correct. Otherwise there were about a dozen days in a row with PM10 over the limit. Those 3 missing days may have been the highest of the year. Who knows? You may think that missing 10% of the data during the most important time of the year is acceptable. You're entitled to your opinion. My opinion is that the numbers have been wrong on about 10 days in the past 30 (including the past 3) when there have been hourly readings below 40. imo, with over 30% of the data questionable, none of the statistics can be relied upon. I refuse to believe that the air for the last 2 or 3 days is as good as it gets with regular hourly readings of below 40. Being generous, the I'd say the reading now can't be less than 50, despite the official reading of 25. How do we know that the 200 readings of last week are accurate? Maybe they were reduced by 50% too, making the 200 in reality 400.

Priceless can compile all the statistics he wants. And I appreciate them. But if you just compare the burning season (use the worst 30 or 45 consecutive days each year, rather than fixed dates on the calendar) over the last 5 years from 2008 thru the current year (please adjust for the omissions and errors this year), it's hard to argue that the trend isn't towards more pollution. Maybe the trend over the last 10 or 15 years is down. Maybe over the last 5,000 years too. But except for the unusual rains of 2011, the trend during burning season over the last 5 years is upwards.

And, Winnie, you can build all the statistics you want, but until the govt stops sponsoring the burning there's no reason to believe it will get better in the near future.

[Priceless]

It may not always be a totally fair comparison to use the hourly reading to the 24 hour hour average, but if I look up at Doi suthep 2-3 kms away and can barely make out the outline of the mountain, yet the current hourly reading is 25, I know something is wrong.

The Nation reported last week that the PCD said CM had 6 consecutive days of PM10 over the 120 limit (I understand the difference between various govt's limits). In an earlier post you said there were 3 days where there were no readings. Coincidentally, those 3 days immediately preceded the 6. The PCD obviously thinks that the zeros are correct. Otherwise there were about a dozen days in a row with PM10 over the limit. Those 3 missing days may have been the highest of the year. Who knows? You may think that missing 10% of the data during the most important time of the year is acceptable. You're entitled to your opinion. My opinion is that the numbers have been wrong on about 10 days in the past 30 (including the past 3) when there have been hourly readings below 40. imo, with over 30% of the data questionable, none of the statistics can be relied upon. I refuse to believe that the air for the last 2 or 3 days is as good as it gets with regular hourly readings of below 40. Being generous, the I'd say the reading now can't be less than 50, despite the official reading of 25. How do we know that the 200 readings of last week are accurate? Maybe they were reduced by 50% too, making the 200 in reality 400.

Priceless can compile all the statistics he wants. And I appreciate them. But if you just compare the burning season (use the worst 30 or 45 consecutive days each year, rather than fixed dates on the calendar) over the last 5 years from 2008 thru the current year (please adjust for the omissions and errors this year), it's hard to argue that the trend isn't towards more pollution. Maybe the trend over the last 10 or 15 years is down. Maybe over the last 5,000 years too. But except for the unusual rains of 2011, the trend during burning season over the last 5 years is upwards.

And, Winnie, you can build all the statistics you want, but until the govt stops sponsoring the burning there's no reason to believe it will get better in the near future.

'It may not always be a totally fair comparison to use the hourly reading to the 24 hour hour average'

No, it is always completely incorrect.

'The Nation reported last week that the PCD said CM had 6 consecutive days of PM10 over the 120 limit'

Presumably March 5-10.

'In an earlier post you said there were 3 days where there were no readings.'

I am fairly sure that I said that there were 3 days (out of 5) with no readings that could be assumed to be in excess of 120 µg/m³. These days were February 25-27.

'Coincidentally, those 3 days immediately preceded the 6.'

No, they did not as February 27 is followed by February 28, not by March 5.

'Those 3 missing days may have been the highest of the year. Who knows?'

Since there were no readings obviously nobody knows, as you point out. However, one can make an educated guess by looking at the results from the other measuring station, Uparaj (which tends to correlate very closely with 'Chiang Mai', correlation coefficient over February-March of this year: 0.96). Here is a graph with the readings for those two stations, clearly showing that the Uparaj readings for February 28-29 were well below the 120 threshold (84.3 and 85.4, respectively). It is extremely unlikely that the 'Chiang Mai' values for the same dates would be over 120.

I'll refrain from commenting on your speculations, since there is nothing outside of your imagination to support them.

'the trend during burning season over the last 5 years is upwards.'

I'm not going to waste my time doing a special linear regression to determine the exact trend line for the last five years. However, this graph shows the 10-year trend line and it is very clear, to anybody who can read a graph, that the trend has also been falling for the last five years:

/ Priceless

[WinnieTheKhwai]

the one thing I'd like to add is that the last two days has been a change of weather, and a bit strange weather with more moisture in the air. When looking at the mountain the top half was not visible, but the sides were. There was actually some cloud cover and/or moisture higher up in the air. Looking horizontally in the distance along roads it's very clear, clearer than it's been since early Feb. So the readings seem factual at 40-50.

Looks like rain now by the way, on the weather radar I can see showers in all directions except the immediate Chiang Mai city area and surroundings. (Note that it doesn't have to rain right on top of you for the air to still clear, though I would appreciate some rain right on top of my garden, too.)

Edited March 12, 2012 by WinnieTheKhwai

[Tywais]

Looks like rain now by the way, on the weather radar I can see showers in all directions except the immediate Chiang Mai city area and surroundings. (Note that it doesn't have to rain right on top of you for the air to still clear, though I would appreciate some rain right on top of my garden, too.)

Near Hang Dong - thunder, lightening and strong winds now.

[chiang mai]

Big wind on my balcony a few minutes ago, read into that what you will!

[chiangmaiexpat]

This is a case of apples and oranges. The reading of 25 is an hourly reading.

Um, no.

It is actually the PCD's official daily average for the Cityhall station for Sunday the 11th. 25.5975 to be precise.

I thought you were keeping up with the numbers?

Cheers, CMExpat

[T_Dog]

I hope this group can get the right Thai backing that has some clout. Worth signing the petition at any rate......

http://www.breathecampaign.net/