Japanese authorities told the International Atomic Energy Agency (IAEA) that radiation levels at the plant site between units 3 and 4 reached a peak of some 400 millisieverts per hour. "This is a high dose-level value," said the body, "but it is a local value at a single location and at a certain point in time."
Later readings were 11.9 millisieverts per hour, followed six hours later by 0.6 millisieverts, which the IAEA said "indicate the level of radioactivity has been decreasing."
Almost all people living within 20 kilometres of the plant have already been evacuated and supplied with potassium-iodide pills that will protect them effectively against the effects of iodine-131 that could conceivably be emitted in the future. The pills saturate the thyroid gland and prevent the radioactive iodine-131 from being absorbed, dramatically reducing the risk of thyroid cancers, which are the major potential health effect from the possible progression of the accident.
The IAEA said 150 people from around the site have been monitored. The results of some people have been reported and 23 have undergone decontamination.
