According to http://www3.nhk.or.jp/daily/english/12_51.html http://www3.nhk.or.jp/daily/english/12_51.html the exposure level measured outside the plant is 1.01

According to http://www3.nhk.or.jp/daily/english/12_51.html http://www3.nhk.or.jp/daily/english/12_51.html the exposure level measured outside the plant is 1.015 mSv / hr. Exposure to about 1000 times that hourly level in a short time period is needed for life-threatening acute radiation poisoning. Exposure to 1.015 mSv / hour for a year would give a dose equivalent of 8.9 Sv - the excess relative risk of cancer for low dose chronic radiation exposure is about 0.97 per Sv - so the exposure to that level for a year would drastically increase cancer risk. Obviously, people won't be allowed into the areas where radiation levels were that high. I saw a report of a worker acutely exposed to >100 mSv; that single event would be enough to increase that worker's lifetime risk of cancer by about 10%.