Disaster in Japan has forced humanity to speak again with anxiety about the dangers of radiation. But the real horror is that to understand this without special knowledge is impossible.Fear is all incomprehensible. To sort out what on television telling the experts, the ordinary man more difficult because the measuring radiation levels and to assess its risks are still using a dozen different units. X-rays, bery (the biological equivalent of radiation), curie, Grays, Becquerel, Sievert - they are so many precisely because for many decades, all work on nuclear issues, strictly confidential, and each country has its unit of measurement.
In recent years, to measure radiation levels to apply the new international unit - the sievert and thousands and millions of shares. In these units report to the data on the situation and the Japanese. The true meaning of this unit only understand physicists, but we need to know that the maximum safe dose for humans is 100 millisieverts per hour. Natural background radiation is from 12 to 16 micro sievert per hour.
Now, the real danger. Radiation dose of 1-2 Sievert per hour (ie 1-2 million micro sievert!) Can cause radiation sickness. Single irradiation dose of 3.5 sievert damages the bone marrow so much that without adequate care for a month or two are killed every other person. Higher doses of damaging the lungs and gastrointestinal tract - the death occurs within 10-20 days. A dose higher than 15 sievert can kill a person in a matter of days.
When hydrogen explosion at a Japanese nuclear power plant in the atmosphere were radioactive iodine and cesium. The half-life of iodine - 8 days, that is, a week later the dose is reduced exactly by half. And after 40 days it will be completely safe. The half-life of cesium is 30 years old, which means that, falling to the ground from the atmosphere, it will be a long time to accumulate in the environment - plants, animals and humans. In the body it penetrates the respiratory system and digestion, accumulates in muscle and liver. Biological half-life of cesium from the body considered equal to 70 days.
That is, if he ceases to act in person with air and food, we finally cleared the organism from him about a year. But in reality, this time may be more or less - a lot depends on health, nutrition, use of different sorbents that bind him and excreted. In this capacity, using barium sulfate, sodium alginate, and others. To calculate the radiation dose specifically to each individual, to the radiation background is multiplied by the time that people spent in contaminated areas.
For emergency prevention of radiation sickness usually applied iodine. He quickly accumulated in the thyroid gland, radioactive iodine, and there's just no room left. That is why the Japanese authorities have ordered to give tablets containing iodine, all the evacuees from the area of the accident.
