Changing into slippers when entering the nuclear medicine management district prevented pollution expansion. Accidents involving patients falling occurred in university facilities. It was thought that changing slippers was the cause. The pollution situation was measured in three facilities by using the smear method and the direct technique to examine the effect of changing slippers. The current state was measured. After pollution prevention guidance was continuously done, pollution expansion was measured; three weeks of measurements were compared. Pollution was detected in the first period of weeks at a frequency of 19 times. For the latter period, it was detected 6 times. Half the pollution was in the restroom. Pollution was reduced by doing pollution prevention guidance for the restroom. Patients' falls occur even if they change slippers. Falling accidents can be decreased.