Keywords:Fukushima Daiichi Nuclear Power Plant accident, indoor radioactive substances, temporal changes, former evacuation areas
With the lifting of evacuation orders and the certification of “Specific recovery and revitalization base area revival and revitalization plan", the number of the returnees is predicted to increase. Information in line with the current situation becomes more important. In particular, information in residential houses is important since residents spend large portion of their time indoors. We are continuing to investigate remaining radioactive substances in residential houses within former/current evacuation areas since 2012. Information on remaining indoor radiocaesium is important for residents since it might cause internal exposure. In this study, we present the temporal changes in remaining indoor contamination.