Air Lab – A portable and open air quality measuring device

Re:Air Lab – A portable and open air quality measuring device by radicality on Thursday June 05, 2025 @12:03PM (#44192960)

Oh yeah? That’s surprising, I’m doing something similar - with esp32s from M5stack, specifically their SCD41 sensor for co2 (same as in the device in the post), with an AtomS3 to drive it, and it’s super responsive and I think very accurate. Perhaps you have the scd40? It’s rated for high accuracy up to 2000ppm, while scd41 maintains accuracy up to 5000ppm.

Using with esphome and homeAssistant, I grab the data every 5 seconds (I did 1s too but seemed unnecessary), and push it to HomeAssistant. The moment I turn on the oven, or open a window, or just enter the room after the night from the bedroom, the graph moves very very visibly and very quickly. I like this setup much more than my uHoo Air sensor.

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Re:Air Lab – A portable and open air quality measuring device by Havoc on Thursday June 05, 2025 @12:55PM (#44193420)

Have a similar setup. Unfortunately the open a window thing isn't all that reliable as test. Even sensors cheaper than the SDC40/41 will happily do that.

The issue is more drift and that its a very localised measurement. The sharp spikes in the graphs are often more about the air is moving than the room's total CO2 changing. Like on mine (also sdc41) I can see when I wake up on the bedroom one. Being awake produces more CO2 sure but it's marginal. 80% sure the spike is simply more turbulence in room. Lying still for hours vs getting up and making bed etc

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