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AirGradient Forum

Do these PM 0.3 values seem right? Are they high, or is the sensor being weird?

#1

I have two AirGradient units in my house in different rooms. They both detect 0 PM 2.5 (very rarely 1), but their PM 0.3 readings seem consistently high to me. One room never gets below 30, and currently is reading 156! The other occasionally gets as low as 5, but typically is over 20.

I can’t seem to easily find any good references about smaller particles. Do these numbers make sense, or are they clearly wrong? Is my house covered in asbestos or what?

#2

The PM03 are particle counts and not ug/m3 as the other PM parameters.

So it’s normal that they are a lot higher.

#3

Some questions:

  • Is there any guidance on thresholds of concern for these particle counts?
  • Any rough mapping of absolute counts to ug/m3?
  • I couldn’t really find guidance re: ug/m3 or ppb for this particle size either – it seems like there’s a lot of info about PM 2.5 particles, but when I search for PM 0.3 all I come up with is explainers about Brownian Motion and how HEPA filters work. Are there any bits of guidance from the EPA, some other governmental agency (any country), or scientific journal articles that talk about it?

I can see in my own house that either the two sensors are not calibrated the same, or one room has about 2x the amount of another room as a matter of course.

#4

Have you tried moving both sensors to the same room?

In my house I consistently have a reading of 0 for pm2.5 but 0.3 is over 100 like yours.

To make sure, I brought my unit outside and saw a jump in numbers that made it similar to what AirNow shows for my area.

#5

I haven’t tried moving the sensors to the same room yet… I’m planning on letting them exist in their separate rooms for a few days, and then swapping them. Not quite sure if that’s the best approach, and I’ll probably put them in the same room at some point to get a direct comparison between what they are reporting.

#6

I do research regarding health effects of ultrafine airborne particles such as PM0.3 or PM0.1. It is a relatively young reseach field with many open questions. Scientists around the globe work on this emerging topic.

We know that the total mass of these particles is generally very low, whereas the total particle number is very high. The latter raises the question whether these particles pose a health risk. I am unaware of guidance from health or environmental agencies regarding PM0.3 or PM0.1, which is likely the result of the unclear health implications.

For scale: a 0.1 micrometer particle is equally long as 1000 hydrogen atoms. This comparison emphasises that we get close to the atomic level of matter, which makes research complex.

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