In Chernobyl, an area 30 km from the nuclear plant, where the radiation level was 0.232 μSv/hour, was declared “no-entry zone”. In Chernobyl, in area where radiation levels were daily even 0.16 μSv/hour have been admitted as being dangerous, and in fact, adults got leukemia and died.
Annotator: In case, in Kamakura, were I live, the level is 0.16 μSv/hour.
Concerning the gamma dose rate in a certain spots one meter above the ground level, the radiation levels declared officially for Kamakura city are generally between 0.11〜0.14 μSv/hour.
Radioactivity, in case of of iron, concrete, etc causes the oxidation and corrosion, but in humans accelerates the aging process and cause them sickness.