Realistic values for PM 2.5?

Hey guys. I booted up my AirGradient DIY yesterday and the PM values were all at 0 for a long time. They did eventually pop up when we cooked dinner. So I’m wondering if this looks about right? I expected to see slightly higher than 0 but I have no frame of reference.

I flashed ESPHome on the board and this is the Home Assistant history graph from the past 24h. The numbers pop up to 1 every once in a while, too, with a max of 52. I had also installed the official AirGradient version via Arduino but that also reported 0.


Edit: whoops, just read Question about overall calibration and why my numbers are all over the map? and looks like that answers my question.

I’ve had the same thing, where mine was showing 0 and wasn’t sure if that was correct. I went to for my zip code and click on More Details under Air Quality to get an estimated PM2.5 for your area. Mine was really low for my area, 7-10, and inside should be lower than outside, so I think it is reasonable for it to be 0.

You could try taking it outside for 10 min and see if it shows non-zero numbers.

Easiest is just to create some smoke, e.g. with a candle. The sensor should pick this up quickly.

Also, keep in mind that we display PM2.5 in µg/m3 and not US AQI. In low concentrations, US AQI is roughly 3 times µg/m3.

So the unit might give the impression that the sensor shows too low, if people are used to the US AQI index.

You can calculate the values with this calculator: AQI Calculator - US EPA Scale convertor

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