Indoor radon daughter dynamical behaviour in a low ventilation dwelling

A dwelling in M?traderecske in the Hungarian north-east region was selected to study the radon daughter (RD) behaviour in a family room with natural low ventilation under living conditions. The selected house is erected on a geology where a relatively high radon concentration with yearly average of 1KBq/m3 exists. The room is considered a natural radon chamber where the most convenient environmental conditions are. Radon concentration was measured continuously by a monitor (Atmos10, Gammatechnik Sweden and Pylon Electronics of Canada). The RD concentration and its temporal and spatial variation were monitored using an electrostatic collector as described by Samuelsson (Linkoping University, Sweden). A similar instrument was built to measure RD transport under laboratory conditions so that an approximate model could be optimized (Rodriguez J. USB- Thesis, 1998). Results indicate that RD has a growing rate of a quarter with respect to the radon concentration increase. Fluctuation of radon gas and its daughter has a delay time of more than two hours. We also observed that ventilation is an effective means to reduce indoor radon concentration and the RD recovering time is approximately 14 hours.
Moreover as dust content increases, radon daughter concentration diminishes. Smoke and water moisture were considered. As expected a complex behaviour was observed and it could not be described by a simple transport equation. In few cases the predicted exponential RD spatial distribution was measured