New Method: Indoor 220Rn (Thoron) Measurement by Rad-7 Based on Micro-Solenoid Valve

Increasing attention has been paid recently to the radioactive gas-²²⁰Rn (thoron) which arouses concern on indoor air quality and human health. A new method of measuring indoor thoron has been illustrated and used to investigate the indoor thoron spatial distribution. The new method realizes fast and reliable measurement of indoor thoron. The thoron concentration is found to decrease exponentially from the walls or floor to the center of the room, no matter whether the door is closed or open, and no matter whether the clay house is decorated or undecorated. The undecorated bare clay house is confirmed to have high thoron concentration in the vicinity of the walls and floor. After it is decorated with newspaper (43 g/m²), the thoron concentration is somewhat lower when the door is closed. But it does not take effect when the door is open. The selected paper (170 g/m²) is proved to be quite effective in reducing the thoron concentration no matter the door is closed or open.