Japanese media report this morning that the radioactive vapor released from the stricken Fukushima Dai-ichi nuclear plant measured 1,557 micro sieverts. The micro sievert is the unit used to measure the biological effects of radiation exposure. Humans average 2,400 micro sieverts per year of natural radiation exposure.
In other news, the operator of the nuclear facility, Tokyo Electric Power Company (TEPCO), announced rolling blackouts of three hours' duration to offset a loss in capacity equivalent to 25% of normal energy use. The blackouts will affect Tokyo and other areas supplied by TEPCO and will occur in cycles over the coming days.