Effects of air conditioning, dehumidification and natural ventilation on indoor concentrations of 222Rn and 220Rn

A bedroom was selected for detailed measurements on 220Rn and 222Rn concentrations and environmental parameters including CO2 concentration, temperature and relative humidity. To simulate different sealing conditions, five conditions were artificially created in the sampling period of 25 consecutive days. It was concluded that natural ventilation is the most efficient way to lower the 222Rn levels, while air conditioning is the next. Dehumidification provides only a marginal reduction of 222Rn levels. The 220Rn concentrations are not affected by natural ventilation, air conditioner or dehumidification, and were all around 10 Bq m−3. There are no significant correlations between the 220Rn and 222Rn concentrations and environmental conditions such as CO2 concentrations, temperature, relative humidity and pressure.