Can't say historical, but 1,000 μsv/year is the annual limit / point at which increase cancer risk exists.
Fukushima disaster levels were 400,000 μSv/h at peak. Short term dose of 10,000
μSv causes radiation sickness but probably not death. Beyond that it gets worse.
Fukushima disaster levels were 400,000 μSv/h at peak. Short term dose of 10,000 μSv causes radiation sickness but probably not death. Beyond that it gets worse.