Radiation Levels In Fukushima

On March 11, 2011, a magnitude 9.1 earthquake hit eastern Japan.

A 43–46 feet high tsunami engulfed scores of cities and

disabled the power supply and cooling of three Fukushima Daiichi reactors,

forcing more than 150,000 people to evacuate from the area.

While radiation levels have declined over the years,

there are still several towns where people cannot return

because of high radiation levels.

The map below shows how radiation levels in Fukushima have changed from 2012 to 2021.

The Japanese government sets a long-term decontamination target at 0.23 microsieverts per hour (μSv/h),

which is the nationally allowed safety standard except medical or natural background exposure.

Green dots show spots evaluated below 0.23 μSv/h

while yellow and red indicate ones above that.

Over the ten years, radiation levels in most of the parts

have dropped below 0.23 μSv/h.

Locations evaluated above 0.23 μSv/h are concentrated

in the no-entry zone around the nuclear plant,

which makes up 2.4% of the prefecture's area.

In 2021, a UN report said that no "adverse health effects"

directly related to radiation from the disaster have been identified among Fukushima residents.

Even if radiation-related adverse health effects do occur in the future,

they will be "unlikely to be discernible," it said.

However, the residency rate in the former evacuation zone is still only 30%.

The number of people who have returned to their hometowns

has remained at a low level due to the fear of radiation and

the fact that some residents have moved their living bases

because of the prolonged evacuation.