The size of these areas is based on daily air-born monitoring that showed last week’s radiation levels were carried approximately 13,000 square kilometers (5,019 square miles), which is about 3% of Japan.
Under the MOE’s previous policy, cleaning up the radiation was implemented in areas with over 5 millisierverts per year, which measured about 1,800 Sq kilometers (695 Sq miles) within Fukushima.
The new policy covers seven times more area than the original estimate. About 60% more land in Fukushima prefecture will be decontaminated.
Some areas of Gunma, Tochigi, Miyagi, and Ibaraki prefectures will be included as well as parts of Chiba, Tokyo and Saitama prefectures.
As reported last week, during the last several weeks, radiation has been carried west by prevailing autumn wind patterns, resulting in an increase in radiation in the northern parts of Gunma and some limited areas of Chiba.
For the first time in several months, on Oct. 6, air-borne radiation levels were in the 10,000 *becquerel range in the extreme northwest corner of rural Tokyo, far away from the metropolitan area.
Yamagata and Kanagawa prefectures measured less than 1 millisieverts of radiation exposure per year.
The MOE is still deciding on an official method to decontaminate these areas.
*The difference between becquerels and sieverts is that becquerels measures radiation emitted and sieverts measures potential for damage to the human body. This is only one of many differences.