The average annual radiation dose of a person living in the United States is 6.2 millisieverts. This includes 2.4 millisieverts per year of natural or background radiation, according to the National Council on Radiation Protection and Measurements, an advisory group. A millisievert is a measure of radiation absorbed into living tissue.
The Chernobyl emergency workers who died within a month of the accident received doses of around 6,000 millisieverts. Over many years the average dose evacuated residents of the area received was 490 millisieverts, according to the World Nuclear Association, a nuclear information and analysis group. The typical dose of a CT scan is about 10 millisieverts, according to Radiology Info.
Over a short time, a 1,000-millisievert dose causes acute radiation sickness; a 10,000-millisievert dose would be fatal within a few weeks.
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