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Cellphone logs help estimate radiation exposure of Fukushima evacuees
Clever.
Chaos reigned during the early phase of the Fukushima nuclear disaster, and people who fled the area have no idea how much radiation they were exposed to before the evacuation. But a scientist has come up with a novel approach to better evaluate their radiation doses by utilizing the logs of GPS-equipped cellphones.
Ryugo Hayano, a physics professor at the University of Tokyo, said he got the idea when he learned that Zenrin DataCom Co., a geographical information service firm, had acquired anonymous-format location logs of Global Positioning System-enabled cellphones with the consent of their users.
He and a co-worker estimated the flow of evacuees on an hour-by-hour basis by using logs of users who were in Fukushima Prefecture when the nuclear crisis began to unfurl. Those users account for roughly 0.7 percent of the entire population of Fukushima Prefecture.
...snip...
The reconstructed flow of people shows that, as of March 15, 2011, only a limited number of people stayed in areas where the central government's simulator, the System for Prediction of Environmental Emergency Dose Information (SPEEDI), gave thyroid gland dose estimates of 100 millisieverts or more for a 12-day period from 6 a.m., March 12, through midnight, March 23, 2011. The SPEEDI doses tend to be overestimates, as they hypothesize a 1-year-old infant who stayed outdoors around the clock.
http://ajw.asahi.com/article/0311disaster/analysis/AJ201305100073
Ryugo Hayano, a physics professor at the University of Tokyo, said he got the idea when he learned that Zenrin DataCom Co., a geographical information service firm, had acquired anonymous-format location logs of Global Positioning System-enabled cellphones with the consent of their users.
He and a co-worker estimated the flow of evacuees on an hour-by-hour basis by using logs of users who were in Fukushima Prefecture when the nuclear crisis began to unfurl. Those users account for roughly 0.7 percent of the entire population of Fukushima Prefecture.
...snip...
The reconstructed flow of people shows that, as of March 15, 2011, only a limited number of people stayed in areas where the central government's simulator, the System for Prediction of Environmental Emergency Dose Information (SPEEDI), gave thyroid gland dose estimates of 100 millisieverts or more for a 12-day period from 6 a.m., March 12, through midnight, March 23, 2011. The SPEEDI doses tend to be overestimates, as they hypothesize a 1-year-old infant who stayed outdoors around the clock.
http://ajw.asahi.com/article/0311disaster/analysis/AJ201305100073