Best And Worst Time Of Day For Air Pollution

[tomahawk]

What do you think are the times of day which are the highest and lowest levels of smog in Chiang Mai. I would have thought early morning would be lower but it seems to me that is not the case.

[CobraSnakeNecktie]

I find the mornings bad because the air tends to be still but conversly there are more fires in the afternoon. I think it comes down to if the wind is blowing and from where.

It could be blowing worse air or better depending on the situation.

[gotlost]

I find it better when all the TV members are on line and at its worst when they are off line.

[realthaideal]

I find that it is essential fires season thread #9 so far. And that's a little more than anecdotal.

I wonder if we'll make it to 20 ?!

[tomahawk]

Yes I believe this is true about the wind. I was in mae Sai the other day and pollution level was much higher than here but did not seem as bad because it was windy. Also, this proves that my teacher did not know about this forum. He said if you ask a stupid question you get a stupid answer. But on this forum it is guaranteed if you ask any question at all, you will get at least one stupid answer.

[CobraSnakeNecktie]

You got the stupid part right. T.V. is like a super dense black hole universe sucking nuclear magnet for attracting the retards.

When I mentioned wind I was more referring to the issue that the CM valley tends to have inversion air circulation pattern which holds and intensifies the air issues. Often times when the wind is blowing it can blow in cleaner air in and bad air out. This time of year wind might just be blowing in more smokey air from as far as Myanmar. So I would not count on wind to always make conditions safer.

Maybe Priceless has a theory on that.

While its true the air feels fresher when the wind is blowing it does not mean the levels of particulate matter are lower.

If I am deciding to exercise I use a smell and visibility test to decide if its a good idea.

[WinnieTheKhwai]

I'm not sure there are daily fluctuations in pollution. (For sure there are fluctuations from day to day, but less sure there are regular patterns within a single day). For sure there are fluctuations in visibility though, with mornings being not as a good as evenings. However that may be due to higher mosture levels in the air in the morning.

[Bill97]

If the problem was smog like they have in Los Angeles, the best air would be early morning and late afternoon/early evening which is confirmed by the available results of hourly data for LA. But the LA problem is gases and the problem here seems to usually be particulates. My guess is that wind helps only if it is strong and long enough to clear the valley significantly and as CSN stated, the wind is bringing clean air.

[WinnieTheKhwai]

Looking at the data for all provinces surrounding Chiang Mai, why would the wind bring clean air? Where would the clean air come from?

[meadish_sweetball]

If the problem was smog like they have in Los Angeles, the best air would be early morning and late afternoon/early evening which is confirmed by the available results of hourly data for LA. But the LA problem is gases and the problem here seems to usually be particulates. My guess is that wind helps only if it is strong and long enough to clear the valley significantly and as CSN stated, the wind is bringing clean air.

LA is located by the sea, isn't it? At least to my limited understanding that would seem to mean a completely different type of weather cycle. Chiang Mai is in a mountain valley far from the sea and no direction I can think of has less burning or cleaner air...

[orang37]

... snip ... But on this forum it is guaranteed if you ask any question at all, you will get at least one stupid answer.

Sawasdee Khrup, Khun Tomahawk,

Yes, that it is a wonderful feature of this forum, and so many other on-line forums: you have the opportunity to develop skills in recognizing ignorance, grandiosity, sociopathy, and brain-damage at the same time as you practice recognizing pro-social behavior, empathy, sincere concern for other's welfare, and open-hearted generous sharing of helpful information

best, ~o:37;

[CobraSnakeNecktie]

If the problem was smog like they have in Los Angeles, the best air would be early morning and late afternoon/early evening which is confirmed by the available results of hourly data for LA. But the LA problem is gases and the problem here seems to usually be particulates. My guess is that wind helps only if it is strong and long enough to clear the valley significantly and as CSN stated, the wind is bringing clean air.

LA is located by the sea, isn't it? At least to my limited understanding that would seem to mean a completely different type of weather cycle. Chiang Mai is in a mountain valley far from the sea and no direction I can think of has less burning or cleaner air...

That is my thought also that wind right now does not really help but wind is more complicated than that with elevation layers like jet stream effects which can be affected by mountain ranges etc.

There is a weather prediction for a high pressure system from China to arrive soon(mar 10) and cause some thunderstorms and strong gusts in N. Thailand. Keeping my fingers crossed it will put some of these particulates onto the ground.

[orang37]

... snip ... There is a weather prediction for a high pressure system from China to arrive soon(mar 10) and cause some thunderstorms and strong gusts in N. Thailand. Keeping my fingers crossed it will put some of these particulates onto the ground.

Sawasdee Khrup, Khun CobraSnakeNecktie,

We were just wondering why WeatherUnderground.com was predicting a high of only 28C (82F) with twenty percent chance of rain this Wednesday, while ThaiVisa's weather service (a few hours ago was predicting a high of 19 C !) is now predicting 29C. As of now, TV is predicting a low of 24C, and WeatherUnderground a low of 19C.

We're going to cross our legs behind our back and join you in praying for Chinese mercy of the meteorological flavour !

Down with particulate matter !

best, ~o:37;

p.s. in Mae Sai yesterday (Sunday); severe haze; estimated visibility about a kilometer at most.

[Priceless]

You got the stupid part right. T.V. is like a super dense black hole universe sucking nuclear magnet for attracting the retards.

When I mentioned wind I was more referring to the issue that the CM valley tends to have inversion air circulation pattern which holds and intensifies the air issues. Often times when the wind is blowing it can blow in cleaner air in and bad air out. This time of year wind might just be blowing in more smokey air from as far as Myanmar. So I would not count on wind to always make conditions safer.

Maybe Priceless has a theory on that.

While its true the air feels fresher when the wind is blowing it does not mean the levels of particulate matter are lower.

If I am deciding to exercise I use a smell and visibility test to decide if its a good idea.

If this is true, maybe you have a theory as to why the Chiang Mai valley regularly has less air pollution than the provinces outside the valley, i.e. on the other side of the mountain ranges?

/ Priceless

[Bill97]

If the problem was smog like they have in Los Angeles, the best air would be early morning and late afternoon/early evening which is confirmed by the available results of hourly data for LA. But the LA problem is gases and the problem here seems to usually be particulates. My guess is that wind helps only if it is strong and long enough to clear the valley significantly and as CSN stated, the wind is bringing clean air.

LA is located by the sea, isn't it? At least to my limited understanding that would seem to mean a completely different type of weather cycle. Chiang Mai is in a mountain valley far from the sea and no direction I can think of has less burning or cleaner air...

Yes, LA is different. A significant off shore wind can push the bad air out to sea. The more common onshore wind just keeps it in the LA basin.

And yes, I too think it is a very unlikely possibility that at this time of year Chiang Mai would get a wind bringing significant clean air. Perhaps we will be pleasantly surprised by CSN's high pressure system due to arrive in 2 days, rain seems to bring relief.

[WinnieTheKhwai]

You got the stupid part right. T.V. is like a super dense black hole universe sucking nuclear magnet for attracting the retards.

When I mentioned wind I was more referring to the issue that the CM valley tends to have inversion air circulation pattern which holds and intensifies the air issues. Often times when the wind is blowing it can blow in cleaner air in and bad air out. This time of year wind might just be blowing in more smokey air from as far as Myanmar. So I would not count on wind to always make conditions safer.

Maybe Priceless has a theory on that.

While its true the air feels fresher when the wind is blowing it does not mean the levels of particulate matter are lower.

If I am deciding to exercise I use a smell and visibility test to decide if its a good idea.

If this is true, maybe you have a theory as to why the Chiang Mai valley regularly has less air pollution than the provinces outside the valley, i.e. on the other side of the mountain ranges?

Possibly because the polluted air from Burma etc. has more trouble to cross the mountain ranges and into our valley? This may explain why other areas experience higher pollution levels before we do. On the same token, this may mean it sticks around longer once here, unless of course rain enters the equation and rains all the crap into the ground.

[CobraSnakeNecktie]

You got the stupid part right. T.V. is like a super dense black hole universe sucking nuclear magnet for attracting the retards.

When I mentioned wind I was more referring to the issue that the CM valley tends to have inversion air circulation pattern which holds and intensifies the air issues. Often times when the wind is blowing it can blow in cleaner air in and bad air out. This time of year wind might just be blowing in more smokey air from as far as Myanmar. So I would not count on wind to always make conditions safer.

Maybe Priceless has a theory on that.

While its true the air feels fresher when the wind is blowing it does not mean the levels of particulate matter are lower.

If I am deciding to exercise I use a smell and visibility test to decide if its a good idea.

If this is true, maybe you have a theory as to why the Chiang Mai valley regularly has less air pollution than the provinces outside the valley, i.e. on the other side of the mountain ranges?

/ Priceless

Well define regularly? Recently it has been better but that has changed in the last few days as CM PCD readings have climbed into dangerous levels.

An inversion effect would tend trap in local emissions. One benefit is that as time goes on CM valley is decreasing its percentage of agriculture use as land values increase and subdivisions etc are built.

Is anyone postulating that the CM valley does not have periodic inversion air flows which trap emissions?

Some of the other provinces you allude to are almost 100% agriculture based so I would expect their seasonal burning to produce more emissions and hence higher PM levels.

CM certainly has more emissions from car, tuk tuks, restaurants etc due to the denser population and traffic. Modern car emissions increase the PM <2.5 which aren't even measured in Thailand.

During periods of non agriculture burning I anectdotally observe the air tends to be cleaner outside the valley. Perhaps that is due to less traffic and restaurants etc.

I don't think its a simple analysis by any stretch. Many variable factors to consider.

[WinnieTheKhwai]

Whoa, look at at this:

That's 278 for Mae Sai.. That's.. unimaginable..

[Priceless]

If this is true, maybe you have a theory as to why the Chiang Mai valley regularly has less air pollution than the provinces outside the valley, i.e. on the other side of the mountain ranges?

/ Priceless

Well define regularly? Recently it has been better but that has changed in the last few days as CM PCD readings have climbed into dangerous levels.

An inversion effect would tend trap in local emissions. One benefit is that as time goes on CM valley is decreasing its percentage of agriculture use as land values increase and subdivisions etc are built.

Is anyone postulating that the CM valley does not have periodic inversion air flows which trap emissions?

Some of the other provinces you allude to are almost 100% agriculture based so I would expect their seasonal burning to produce more emissions and hence higher PM levels.

CM certainly has more emissions from car, tuk tuks, restaurants etc due to the denser population and traffic. Modern car emissions increase the PM <2.5 which aren't even measured in Thailand.

During periods of non agriculture burning I anectdotally observe the air tends to be cleaner outside the valley. Perhaps that is due to less traffic and restaurants etc.

I don't think its a simple analysis by any stretch. Many variable factors to consider.

I based my statement about "regularly" on three (albeit inter-related) criteria: Average yearly pollution level, average monthly pollution level during the "peak season" and number of "bad days" (i.e. with PM<10 greater than the PCD standard of 120 µg/m³).

PCD only started posting full-year data for Northern provinces other than Chiang Mai and Lampang from the beginning of 2009, so there is not that much data available as of yet. These are the yearly pollution levels (in µg/m³) for 2009 with the number of "bad days" in parentheses:

Chiang Mai: 41.6 (16)

Chiang Rai: 49.4 (28)

Lampang: 57.6 (33)

Lamphun: 45.4 (18)

Mae Hong Son: 45.6 (33)

The average monthly pollution levels can be seen in this graph:

Your "anecdotal" observation that "the air tends to be cleaner outside the valley" does not seem to be supported by this graph (or the underlying table). I would actually have expected more of a difference in non-burning season, due to greater traffic, population density and so on, but the greatest difference (i.e. with Chiang Mai having a higher value) in 2009 was 5.3 µg/m³, i.e. very marginal.

The number of "bad days" so far this year can be seen in the following graph:

It is very interesting that you (implicitly) claim that Chiang Mai has an unusually high incidence of inversions. Have you got a source for this?

It is rather self-evident that pollution has many different sources. It would require a lot more serious research to prove anything in this case, in particular with only just over a year of data, but I still tend to agree with WinnieTheKwai that neighbouring countries, in particular Burma, may play a much greater role than what is generally thought. It appears to me that the mountains, rather than trapping pollution in and around CM, may actually be protecting us from the worst of the onslaught.

A further case in point: On 27 February PCD started posting pollution figures for Mae Sai, i.e. even closer to the Burmese border than Chiang Rai. The (scary) results for the eleven days of records so far are:

/ Priceless

[CobraSnakeNecktie]

Priceless I think you read into I was saying CM has an 'unusually' high number of inversion days. I'm not in the "its really bad camp" or the "its fine camp" when it comes to air pollution. I'm not sure what constitutes average or above average inversion days. Local small aircraft pilots might have an idea. Anyway inversions tend to occur at the base of mountains as the air is not powerful enough to flow over and just recirculates similar to an eddy in the water. Temperature gradients have something do with inversions also.

When I said the air tends to be cleaner out of the valley then how could you know the air quality up in the mountains is not better? Isn't the mobile station up by the palace almost always better air quality? I would still stick to that anectdotal analysis if based on nothing more than just more trees to clean and refresh the air. When I used to live in Boulder Colorado at the base of the rockies it was common to have inversion flows and when descending back into the valley it was apparent because it like a brown cloud. Feels the same to me here. Perhaps that is just localized pollution and not an inversion. Not sure really.

I would tend to agree Myanmar really looks like a major likely source of a lot of this now and perhaps a lot of the year. The high levels at Mae Sai seem to really implicate Myanmar.

[Ulysses G.]

A buddy just came back from visiting Luang Prabang and reports that the whole town and the whole area is immersed in one big cloud of smoke. That is what it looked like 10 years ago at this time of year, so this is nothing new.

[CobraSnakeNecktie]

it's raining !!!!! how cool is that

Edited March 10, 2010 by CobraSnakeNecktie

[scotbeve]

Here's todays PCD report.... what's wrong with the numbers here??? See it? And what was up with yesterdays PCD report (Eg: NO numbers in for Chiang Mai and Pae (assuming that is supposedly Pai))?

http://www.pcd.go.th/AirQuality/Regional/default.cfm

[WinnieTheKhwai]

Well, what's wrong is that yesterday (todays' report) was the first 'bad' day this season. The numbers for Mae Hong Son, Chiang Rai and especially Mae Sai remain horrific though. I seriously hope that crap doesn't come our way, and/or the area gets some decent rain today.

[scotbeve]

it's raining !!!!! how cool is that

YAAAAY!!!! Raining as I was writing my last post!!! Great! Let's have some more! AND it's a bit windy...

[orang37]

Priceless I think you read into I was saying CM has an 'unusually' high number of inversion days. ... snip ...

Sawasdee Khrup, Khun CobraSnakeNectie, and Khun Priceless,

Once again may we thank you both for continuing an interesting and edifying dialog (such a dialog, without the usual ad hominems, and irrelevant spew from fried-farang-brains [Thai: 'samong farang thod' ?], being a "gem" in the context of TV CM, ioho).

We do believe that in some years there is a definite and "deadly" air-trapped-by-inversion phenomenon in the riverine flood plain etched by the Ping over time. We'd hypothesize that those days of "pollution hel_l" we experienced here several years ago were contributed to by a change prevailing wind conditions: most likely a lack of wind.

Khun Priceless mentioned Colorado, and, of course, Denver is famous for pollution from trapped-air inversion.

Hypothesis : the high-pollution northern Thai sites have in common that they are all cities in flood-plains of rivers which is directly related to the fact that historically northern Thailand city demography developed around the rich fertile river valleys which support the production of some of the world's best rice in two crop cycles per year.

Null Hypothesis : find a northern Thai city (occupied for centuries, not some new "industrial zone") with major population numbers that is not in the flood-plain of a river, which is also "surrounded" by nearby mountains, which has very little pollution problem.

Exclusionary Hypothesis : exclude, or discount, Lampang's off-the-scale pollution because there are other distinctly identifiable sources of pollution which are clearly modern in origin: the Mae Moh lignite-burning plant ? Note: we have not read anything about the Mae Moh plant since the March, 2009, major victory of villagers and environemental groups over EGAT Nation on 2009 Victory over EGAT re Mae Moh Power Plant : is it still going and a major source of pollution ?

Again we'd like to draw your attention to patterns of prevailaing winds, and variability in patterns of prevailing winds (and/or lack of wind) as a possible major factor in what type of pollution travels where (or "sticks" around), and where pollution settles: we still think this has not received enough attention and discussion here.

best, ~o:37;

Edited March 10, 2010 by orang37

[CobraSnakeNecktie]

Thanks for the constructive dialogue Orang

Tomahawk had a good initial question. Are there times of the day or other anomalies that can be exploited to avoid air pollution and its well documented health risk side effects?

I think most of us can agree there is 'some' significant pollution in CM. Short of leaving what strategies can be used to minimize its effect?

I alluded to some of my tricks like getting out of the valley into the mountains for exercise or waiting for breezy periods and using my nose and eyes to guage situations.

How does one stay in CM and remain healthy? Its a good train of thought.

Edited March 10, 2010 by CobraSnakeNecktie

[Priceless]

Priceless I think you read into I was saying CM has an 'unusually' high number of inversion days. I'm not in the "its really bad camp" or the "its fine camp" when it comes to air pollution. I'm not sure what constitutes average or above average inversion days. Local small aircraft pilots might have an idea. Anyway inversions tend to occur at the base of mountains as the air is not powerful enough to flow over and just recirculates similar to an eddy in the water. Temperature gradients have something do with inversions also.

When I said the air tends to be cleaner out of the valley then how could you know the air quality up in the mountains is not better? Isn't the mobile station up by the palace almost always better air quality? I would still stick to that anectdotal analysis if based on nothing more than just more trees to clean and refresh the air. When I used to live in Boulder Colorado at the base of the rockies it was common to have inversion flows and when descending back into the valley it was apparent because it like a brown cloud. Feels the same to me here. Perhaps that is just localized pollution and not an inversion. Not sure really.

I would tend to agree Myanmar really looks like a major likely source of a lot of this now and perhaps a lot of the year. The high levels at Mae Sai seem to really implicate Myanmar.

I am sorry, in my earlier posts I assumed that you actually knew what an inversion is. An inversion is an abnormal temperature gradient in that, at some altitude, the temperature actually increases , rather than decreases, with increasing altitude. This can lead to pollution being trapped close to the ground. From what I can remember from my meteorology classes, there is no correlation between the frequency of inversions and the proximity of mountains. However, the "locking in" effect of inversions is frequently stronger in valleys such as the one where Chiang Mai is located.

That pollution tends to stay close to the ground, say within a few 1,000 feet, is probably more due to the law of gravity than to inversions. An inversion will exacerbate this effect though, as has been said happened in CM in 2007.

/ Priceless

[orang37]

... snip ... That pollution tends to stay close to the ground, say within a few 1,000 feet, is probably more due to the law of gravity than to inversions. An inversion will exacerbate this effect though, as has been said happened in CM in 2007

Sawasdee Khrup Khun Priceless,

Would you say that a lack of wind is usually associated with an "inversion" ?

If we accept that pollution obeys the laws of gravity, then isn't a logical corollary the assumption that for pollution to move somewhere else from where it originates: it must be first lifted up through the application of some kinetic energy, and second moved laterally by some kinetic energy ?

Naturally, we can assume that the smoke and hot-air of fires rising lift up particulate matter, and once lifted up into the atmosphere, wind must, logically, be the only "extra" force of kinetic energy that can cause it to move some distance ?

If we were in the middle ages, we could discuss the possibility of miniature beings with wings being born in rice burn-off. and mountain-side fires. and flying, and the possibility of flagellation and extreme spiritual techniques being used to neutralize these hypothetical flying particulate-demons ? But alas, the Unicorns, and the Mom-Makara of yore, and Upagruta in his ruby palace at the bottom of the sea, are gone for most us.

We beg you to dip into your "well of scientific knowledge," and speak to us about : wind

best, ~o:37;

[CobraSnakeNecktie]

Okay great then we have a non 'inversion' situation of pollutants being trapped in a valley. Lack of air flow or gravity being the more likely cause with less likely or unknown periods of infrequent or rare thermal inversion. Doesn't particularly change the spirit of the observations about relative concentrations of pollutants being trapped in the valley. Thanks for the clarification on terminology.

I noticed you just glossed over my postulated theory of greater <2.5 pm matter in CM due to combustion of hydrocarbons. If two different locations had comparable PM 10 levels but one area had significantly more 2.5 pm as a percentage of PM 10 then wouldn't the area with more 2.5 represent a greater health risk?

It's my understanding that burning hydrocarbons under pressure for example in vehicles creates these smaller and more health risky particles. Further it's my assumption that dense CM with its traffic and restaurant concentrations would be producing a lot more 2.5 pm hydrocarbon emissions than a agricultural region.

On the one hand the smaller pm 2.5 particles lodge deeply into the lungs and seem to be associated with more rapid cardiovascular damage as well as the increased transportion of toxins to the blood stream.

On the other hand I have generally made the assumption that agricultural burning tends to release larger less harmful particles because they are burned under less combustion pressure. Of course there are other factors like pesticides and oil based fertilizers being burned in agriculture settings which might offset the benefit of less PM 2.5.

One question I would find interesting is whether its better to be proximal to sources of agriculture burning or vehicle emissions and their relative health effects.

Kind of getting back to the spirit of the thread about avoiding health risks associated with variable levels of air pollution.

Winnie. Orang, Priceless? it's interesting topic to me because I want to live a long time in good health.