Measurement results of radiation doses in the air (Shinjuku)

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

[graph]Graph of radiation doses in the air (Shinjuku)

Click on the graph for an enlarged display



[graph]Graph of radiation doses in the air (Shinjuku)

Click on the graph for an enlarged display

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).

[Reference]

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 at 1 meter above the ground (From May 2011)

[graph]Measurement at 1 meter above the ground (Shinjuku)

Click on the graph for an enlarged display

[graph]Measurement at 1 meter above the ground (Shinjuku)

Click on the graph for an enlarged display

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.