I've built some DIY air quality monitors. Radon sensors are hard to find.
In general from easiest to hardest:
- Temperature, humidity, pressure: many cheap, small and accurate sensors available.
- Particulate matter: many options as well though if you want good accuracy and silent fans you need to pay more.
- CO2: most sensors are actually just measuring other stuff (TVOC) and guessing CO2 concentration from that. You can get good true CO2 sensors from eg. Sensirion for $30+.
- VOC, CO, NO, O3 and other gasses: hard to measure reliably. Most sensors are comparatively large (few small SMD MEMS types exist), are power hungry (basically a heater element) and give you a crude estimate as they react to bunch of different gasses and the output is a mix of their concentrations.
- Radon: basically impossible for hobbyist. If you know of any sensor module I can buy below $100 in unit quantities please share.
Edit: I know airgradient are not hobbyists and they probably could get some radon sensors but it is still harder than for large companies. Their product definitely has the DIY vibe (but high quality) and I really like that it is easy to recreate and source all parts for it yourself, except the custom injection mold case.
Because Radon actually causes cancer and ventilation is expensive. I’ve read many articles about people going nuts trying to manage CO2, but I think it’s useful to know if I’m being exposed to something that would actually result in early death as I’m more likely to take immediate action on that.
I just want to point out that the other device being compared actually includes a radon sensor and the cost of that device would be cheaper than the airgradient plus the radon sensor.
