PM2.5 Air Quality Sensor Measurement Units

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MrSomethingRed
 
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PM2.5 Air Quality Sensor Measurement Units

Post by MrSomethingRed »

Hello all!

I was wondering if anyone had a deeper idea about what units the PM2.5 Air Quality Sensor outputs in. I can see in the documentation I have the choice between "Standard", "environmental" and particles per decillitre.

While the last one is quite obvious, I am trying to figure out what on earth the other two units are actually measuring in, unfortunately neither the datasheet nor google have been much help here, does anyone have an idea? I am hoping to compare to known measurements reported in micrograms per L.


Cheers!

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mikeysklar
 
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Re: PM2.5 Air Quality Sensor Measurement Units

Post by mikeysklar »

I don't think we will get an answer on the difference between "Standard" and "Environment" in this case. When the datasheet doesn't say and the rest of the internet speculates you will have to just pick one and stick with it. The EPA uses the "standard particle" reading.
Standard PM vs. Environment PM
Nobody seems to know what the difference between these two measurements are. There are only two hints as to which one to use.

The PMSA300I datasheet simply says "CF = 1 should be used in the factory environment" which suggests it is only meant to be used for factory calibration and the atmospheric environment metrics are the ones we should use in real life.

However a number of slides presented by researchers at the US Environmental Protection Agency used the standard particle reading despite the datasheet and point out that it is consistently lower than the atmospheric environment reading. They point out that PurpleAir uses the CF=1 for indoor sensors and CF=atm for outdoor sensors, but I get the impression that nobody but the Plantower folks who manufacture this sensor really know.
https://www.glennklockwood.com/electron ... a300i.html

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MrSomethingRed
 
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Re: PM2.5 Air Quality Sensor Measurement Units

Post by MrSomethingRed »

Thanks for your response! I guess I will just have to do some kind of manual calibration myself!

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