» It’s no longer at its peak, and that’s a good thing: The International Atomic Energy Agency says that the decrease happened over a six-hour period. And the IAEA makes a good point that you should keep in mind. “This is a high dose-level value, but it is a local value at a single location and at a certain point in time,” they say. In other words, even if you’re within the 20-mile radius where radiation is likely to hit, the level will most assuredly be far lower than these peak levels. It’s still high, though – one milli-sievert per hour is equal to the yearly legal limit of radiation you’re supposed to get. (see our earlier posts about this topic here and here)
» This is an extremely large jump: One milli-sievert per hour is the legal annual limit for radiation in a year. Our earlier estimate showed a level of 8,217 micro-sieverts. 1,000 micro-sieverts equals 1 milli-sievert. So we went from 8,000 to 400,000 in a couple of hours. This is still no Chernobyl, but this is a huge jump. If it jumps to 1,000,000 micro-sieverts, it leads to radiation sickness – and then we’re in trouble. (For more info, read these posts: One. | Two. | Three.)
» To explain: This number comparison is to emphasize the difference between an actual going-to-kill-us-all meltdown and what’s happening in Fukushima. While things could get worse from here, right now, the worst of what’s happening in Fukushima is 0.3 percent as bad as the worst of the Chernobyl disaster. 400 rontgen is enough radiation to kill you. 10,000 micro-sievert equals 1 rontgen. Chernobyl was pushing out 30,000 rontgen per hour at its core – enough to kill someone in 48 seconds.
This is an important point to make – while levels are higher than normal, this is extremely minor on the scale of a real disaster. Oh, and one more thing – Fukushima only hit its 8,217 micro-sievert peak for a very short period. Chernobyl’s level was sustained. (EDIT: Please see update. | Second update. | Third update. | Fourth update.)