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PM2.5 Air quality Sensor - Units?

Posted: Sat May 12, 2018 11:20 am
by solaria123
So, the particle counts are particles / 0.1 liter. Multiply by 10,000 to get particles / meter^3

What about the "concentration units"? I assume that's ug/meter^3...
but what's the difference between "standard" and "environmental"?


Re: PM2.5 Air quality Sensor - Units?

Posted: Mon Jun 04, 2018 7:14 pm
by amhamilton
I was hoping for an answer to this same problem. Did you ever find an answer?

Re: PM2.5 Air quality Sensor - Units?

Posted: Mon Jun 04, 2018 11:08 pm
by solaria123

I discovered that it can't actually detect particles > 3um; the numbers it reports are just estimates:
From these measurements, we conclude that the Plantower PMS5003 is able to measure PM2.5 more
or less correct. With a suitable calibration, it may be calibrated to a reference instrument such as the
Grimm. The PMS5003 however is not able at all to directly measure large particles > 3um. When it
outputs PM10 values, these are pure estimates based on particle sizes it can measure (d < 3um) and
under the assumption of a broadly distributed particle spectrum. When the particle spectrum is not
containing PM mass contributions at sizes < 3um, the PMS5003 erroneously outputs PM10 values close
to zero.

These findings intensify the strong suspicion that low-cost PM-sensors, mainly produced by Chinese
manufacturers and designated as PM2.5 sensors but also reporting PM10 values, aren’t able to
measure particles larger than 3um and therefore solely extrapolate on PM10 values assuming a certain
particle distribution. ... _PM-sensor
...but nothing about the Concentration Units. Maybe it has something to do with how it estimates the large particle distribution? Standard vs Environmental particle spectrum?

For my application, using the 0.5 micron counts. When the count exceeds 352, the ESP8266 triggers the HVAC to filter the air...

Re: PM2.5 Air quality Sensor - Units?

Posted: Wed Jun 06, 2018 2:02 pm
by adafruit_support_carter
Check out the info I posted to @amhamilton's similar question here: