Radiation: How much is harmful?

April 07, 2011

How dangerous to human health is radiation from the crippled nuclear power plant in Japan? How does it compare with other nuclear accidents and our everyday radiation exposure?

Not all radiation is the same, so scientists use the ‘sievert’ to measure the health risks of radiation. A one-sievert dose of radiation would cause immediate radiation sickness. But most radiation doses are much smaller, so you’ll see them measured in millisieverts or even smaller microsieverts.

1 sievert = 1000 millisieverts 
1 millisievert = 1000 microsieverts

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