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Comment by ChikkaChiChi | Hacker News Reader

Can anyone recommend a decent CO2 and VOC monitor for a desktop? It'd be great to have something to help tell me when I need to improve the ventilation.

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I use this one https://www.amazon.ca/Autopilot-Desktop-Monitor-Data-Logger/...

I have an unbranded one I bought from Alibaba. It's a box about 50cm x 75cm x 25cm and runs on 2 AA batteries or USB power. Not rechargeable. Right now it's showing 628 ppm CO2. Outside, about 395 ppm, which is about right. If I breathe on it, 1500 ppm CO2. Has data logger functions and a USB port. Costs about $150.

If you just want a light filter for quality/price/utility that a fellow geek applied without having done a buttload (but a bit) of research, I bought one of these and am satisfied:

https://www.amazon.com/gp/product/B07D9SH4M5/ref=ppx_yo_dt_b...

Unfortunately, it's showing out of stock. :-(

I am running ESPHome on ESP8266, sensor is MH-Z19B.

You can also run Tasmota firmware on ESP8266 which means you can easily monitor CO2 value from your browser.

Looks neat, I wonder if you could get it down small enough to run on something wearable like a watch-style device.

Well, you could. I have it on 3D printed case, but have no need for mobility. Of course you would need battery and with small (1000mAh or so) battery it could run at least few days with one charge.

For tVOCs and inaccurate, inferred CO2 readings, absolutely. Sensors like the BME680 or SGP30 are ~4mm square.

For real CO2 sensors, not yet. The smallest accurate sensor I've worked with is the SCD30 and it's much too large to fit into a watch body as-is.

Sensirion has come up with the SCD40 though, which is 12x12x7mm and should make a wearable CO2 sensor feasible.

Thanks for the answer.

Have been using and giving away as gifts "TFA Dostmann AirCO2ntrol Mini CO2-Monitor" devices. Costs around 70 bucks. And sensor values are accessible over its usb data lane fairly easy (there are some python implementations out).

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