Change in the Measurement Frequency of Indoor Radiation Levels

Since the occurrence of the Great East Japan Earthquake, the city has been conducting fixed-point measurements of ambient radiation levels at a height of 5 cm and 100 cm in Elementary and Junior High Schools, Nursery Schools, and Kindergartens within the city, starting from June 2011. In fiscal year 2016, measurements were conducted once a month at 40 locations.
In addition, since February 2012, we have selected locations where rainwater, dust, and dirt tend to accumulate, such as under the rain gutters and rainwater pits of Public Facilities, and we conduct local measurements of the radiation levels at a height of 1 cm above the ground once a year. In fiscal year 2016, measurements were taken at 235 facilities and 729 locations.
In this context, the measurement results from 2011 to the present have been stable, remaining below the standard value set by the Ministry of the Environment (0.23 microsieverts per hour). Additionally, the values from the radiation monitoring posts in Shinjuku, which were established before the Great East Japan Earthquake, have decreased to levels seen before the disaster. Therefore, we will suspend the measurement of ambient radiation levels in the city from fiscal year 2021 onwards. However, if any concerns arise, we will immediately resume measurements.

• Change in Frequency of Ambient Radiation Measurement (PDF 283.9KB)