Measurement results of radiation doses in the air (Shinjuku)

Graph of radiation doses in the air (From March 2011)

We measure radiation dose rate of γ ray in air for 24 consecutive hours throughout the year using the stationary measuring instruments called monitoring posts.

Measured vulue of radiation dose is expressed in a unit “Gy (gray) per hour” which indicates an amount of air absorbed dose as the strength of the amount of energy when radiation hits a material object, and 1 gray (Gy) of air radiation doses can be converted to 1 sievert (Sv).


Green belt in graph means the range of values observed at the Tokyo Metropolitan Institute of Public Health before the accident of Fukushima Daiichi Nuclear Power Plant : 0.028-0.079 µSv/h (the average value is roughly 0.035 µSv/h)

Measurement results
(Latest data)
(Past data)

Measurement at 1 meter above the ground (From May 2011 to March 2017)

We measure radiation doses in the air at 1 meter above the ground (soil) once a day using portable measuring instruments called scintillation survey meters.

Measurement results