After searching for quite long, I’ve just found & successfully implemented a cheap air quality sensor to monitor indoor air quality and thought I share this news because there might be others looking for one.
This one is $25 (they’re usually 100+ $). It’s a USB stick that you can connect to a RPi or other Linux system, see installation instructions here and use exec binding to query it from openHAB.
It’s also being resold under various brands (I actually ordered this one).
