1 Introduction  
1.1 Recent evidence and original radiation data on the Fukushima nuclear disaster  
1.2 Wide area airborne monitoring  
2 Dose rate measurement at hotspots in Kashiwa City  
2.1 Parking lot gutter  
2.2 Paved road gutter  
2.3 Bases of large zelkova trees  
3 Environmental dose decrease  
3.1 Decontamination  
3.2 Dose rate monitoring in the daily living environment  
4 Discussions  
4.1 Rutherford and Soddy law  
4.2 Reliability test of DoseRAE 2  
4.3 The environmental radiation information of the University of Tokyo  
4.4 Dose rate vs. time at several points in Kashiwa City for 12 years  
5 Conclusions