Radon is a radioactive gas that is naturally emitted from the earth's surface and it is basically inert. It's an odorless, colorless, and invisible
Radon Detector Circuit
How to Build a Home-Brew Radon Detector - IEEE Spectrum
Radon Detector RadonEye Home Radon Gas radiation real-time radon monitor Bluetooth version RN200 or Wifi version Plus+2
Radon Mitigation Systems - MN Dept. of Health
EcoSense RD200 RadonEye Home Radon Detector Fast & Accurate Real-Time Monitoring OLED Display Easy Setup with Free App Bluetooth
RD200M : High-performance radon sensor - Radon FTLab
Sensors of radioactivity
How to Build a Home-Brew Radon Detector - IEEE Spectrum
Radon Detector
Ion Chambers
Darlington triplet - static electricity detector? - Electrical Engineering Stack Exchange