Somewhat related: I had trouble with reliability of Adafruit's CircuitPython and MicroPython on various microcontrollers. I couldn't get them to reliably send t

Somewhat related: I had trouble with reliability of Adafruit's CircuitPython and MicroPython on various microcontrollers. I couldn't get them to reliably send their data to an MQTT queue over wifi. So I gave up and bought a couple of AirThings air sensors. Lucky I did. Our furnace air intake pipe had been blocked by multiple birds nests, and the secondary pipe for the water heater was incorrectly connected. Our indoor CO2 levels were higher than 4,000ppm! The levels would also jump when the furnace kicked on, even with windows open. Thankfully apartment complex maintenance was able to fix it immediately and levels are much lower now, especially when the furnace is running. (About 500ppm with windows open, 700 with them closed and furnace running, 1,100ppm if the windows haven't been open and the furnace hasn't run for a while.) It's possible our health has improved because of the sensors. I got 2 AirThings View Plus. I'm not affiliated with the company other than having bought their products.