Decentralised ventilation efficiency for indoor radon reduction considering different environmental parameters

ABSTRACT Radon-222 contributes to half of the natural radiation exposure of humans and is one of the main causes of lung cancer. Of particular importance for humans is the exposure to radon-222 indoors, which enters living and working areas from the soil air, e.g. through cracks in the foundations of buildings. An easy and efficient way to minimise indoor radon in dwellings can be achieved through ventilation. How meteorological parameters and the geological background can influence ventilation efficiency in reducing indoor radon has not yet been fully investigated. Therefore, a decentralised ventilation system was installed in an unoccupied flat located in a former uranium mining region to analyse the effect of already existing ventilation modes on indoor radon activity concentration. It is aimed to assess 22 different ventilation experiments that were performed within the time period of one year. Even with a strong seasonal trend with significantly lower indoor radon activity concentrations in summer compared to winter, the decentralised ventilation system was able to reduce indoor radon by up to 83 %. Thereby, strong dependencies on the experimental parameters such as ventilation type or performance level of the fans were found.