Japan’s science ministry is conducting an extensive aerial survey to see how radiation has spread from the disabled Fukushima Daiichi nuclear plant.
The ministry plans to measure gamma ray radiation at altitudes of 150 to 300 meters and recalibrate the readings to estimate levels of radioactive substances closer to the ground.
The survey will start by October in 22 prefectures ranging from Aomori in the northeast to Aichi in central Japan.
Among the 22, Fukushima and 3 other prefectures have already finished the survey. Three others have begun or are due to begin the operation in August. The remaining 15, including Tokyo, will follow suit in September.
The science ministry has acquired additional equipment to enable it to work quickly, as winter snow could hamper accurate monitoring. All the prefectures are due to complete the survey by the end of the year.