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Lacessit

Are PM 2.5 numbers reliable?

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Background: I have moved from Chiang Mai to Chiang Rai. My PM 2.5 meter in my Chiang Mai condo regularly hit the 100 mark.

The same meter in the Chiang Rai condo is sitting on 50. If I switch on the air purifier, I can get it down to 30 in about an hour. Overnight, I've had it down to 8.

BUT as I type this, Chiang Rai PM 2.5 air quality is officially 156. Can some kind soul explain?

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6 minutes ago, CharlieH said:

According to AQI its 114.

 

You do know the difference between actual AQI and meter readings ? as they are NOT the same thing.

No, that's why I am confused.

I refuse to believe Chiang Rai air quality is worse than Chiang Mai, because the meter, my eyes, and my throat is telling me different.

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1 hour ago, Lacessit said:

... because the meter, my eyes, and my throat is telling me different.

1 hour ago, Lacessit said:

Chiang Rai air quality is worse than Chiang Mai ?

Yes/No. Depending on time and place.

To be sure I would have a second PM2.5-monitor.

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Posted (edited)

@ Lacessit

These stations in/around CR are reporting

the AQI, tonight 113 - 144.

image.png.dd5bb63206024775cab8ce64e06be159.png

AQI 113  means  image.png.2e6a671ea5eae14a121a445e17b2b32f.png

 

AQI 144  means image.png.a169d572cabc3411fecf73f6a4954496.png

CharlieH ^^^ gave you the link to the AQI-Calculator.

             *****************************

 

 

Edited by Yom
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8 minutes ago, stouricks said:

And which would you believe to be correct

My  experience until now: the measurements were always quite similar.

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Chiang Rai generally has lower PM2.5 than Chiang Mai and the temperature is normally about 2 or 3'c lower than CM. Not always though but more often than not. Your meter is probably working fine. 

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Generally no as the 3 websites I check show variable results for my location  but they do show trends which is helpful

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Posted (edited)
23 hours ago, Lacessit said:

No, that's why I am confused.

I refuse to believe Chiang Rai air quality is worse than Chiang Mai, because the meter, my eyes, and my throat is telling me different.

Non linear distribution of particulates. Different conditions in sampling areas, calibration drift, % error of metering instruments etc etc.

Edited by emptypockets
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PM 2.5 use to be about 30-35% of the AQi Value.

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