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Emergency workers were exposed to high
doses of radiation; the surrounding population to far less

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  • A total of 237 occupationally exposed people were admitted to hospitals and 134 were diagnosed with "acute radiation syndrome." Of these, 28 died within the first three months, while at least 14 additional patients have died over the past ten years although these were not necessarily associated with radiation exposure. Two other people died in the explosion, and one more presumably of heart failure.

  • Some 200,000 people involved in the initial clean up of the plant received average total body radiation doses of the order of 100 millisieverts (mSv)-a millisievert is a unit of radiation dose equivalent to about 10 general chest X-rays. This dose is about five times the maximum annual dose limit currently permitted for workers in nuclear facilities (20 mSv per year). Average worldwide natural "background" radiation is about 2.4 mSv annually. An evacuated home within the 30km exclusion zone

  • Some 20,000 liquidators received doses of the order of 250 mSv; a few per cent of them received doses of 500 mSv; and several dozen people received potentially lethal doses of a few thousands of millisieverts.

  • Fewer than 10 percent of the 116,000 people evacuated from the "exclusion zone" received doses greater than 50 mSv; fewer than 5 percent received more than 100 mSv.

  • More than 400,000 people lived in areas contaminated with more than 555 kBq/square meter2- classified by Soviet authorities as areas of strict control, requiring decontamination measures and restrictions on the use of locally produced foods.

  • In Belarus, where an estimated 70 percent of the radioactive releases were deposited, about 20 percent of the population (2.2 million people) continue to live in areas where contamination initially exceeded 37 kBq/square meter-a low level not requiring decontamination and other control measures.

  • For people outside the former USSR, the highest (national) average radiation dose during the first year after the accident was 0.8 mSv, that means an additional dose equal to about one third of the dose due to natural background radiation in that year.
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2 levels of radioactive contamination in this report are given in kBq per square meter. The Becquerel is equal to one atomic disintegration per second. 1 kBq = 1000 disintegrations per second.