After the declaration of a nuclear emergency by the Government at 19:03 on 11 March, the Fukushima prefecture ordered the evacuation of an estimated 1,864 people within a distance of 20 km from the plant. This was extended to 30 kilometres (19 mi) and 5,800 people at 21:23 by a directive to the local governor from the Prime Minister, together with instructions for residents within 10 kilometres (6.2 mi) of the plant to stay indoors.The evacuation was expanded to a 10 kilometres (6.2 mi) radius at 5:44 on 12 March, and then to 20 kilometres (12 mi) at 18:25, shortly before ordering use of seawater for emergency cooling.
News reports at 17:35 JST on 12 March that NHK advised residents of the Fukushima area "to stay inside, close doors and windows and turn off air conditioning. They were also advised to cover their mouths with masks, towels or handkerchiefs" as well as not to drink tap water. Air traffic has been restricted in a 20-kilometre (12 mi) radius around the plant, according to a NOTAM. The BBC has reported as of 22:49 JST (13:49 GMT) "A team from the National Institute of Radiological Sciences has been dispatched to Fukushima as a precaution, reports NHK. It was reportedly made up of doctors, nurses and other individuals with expertise in dealing with radiation exposure, and had been taken by helicopter to a base 5 km from the nuclear plant."
Over 50,000 people were evacuated during 12 March.The figure increased to 170,000–200,000 people on 13 March, after officials voiced the possibility of a meltdown.
On the morning of 15 March, the evacuation area was again extended. Prime Minister Naoto Kan issued instructions that any remaining people within a 20 km (12 mi) zone around the plant must leave, and urged that those living between 20 km and 30 km from the site should stay indoors.A 30 km no-fly zone has been introduced around the plant.
Unlike the Chernobyl Exclusion Zone which is long established and fixed, the evacuation area around Fukushima is constantly under review. Some of the towns originally evacuated have allowed residents to return. However. other areas may remain free of people for some time to come.