[This is a guest written article, views expressed are the authors alone and may not be endorsed by Safecast]
This is a guest post by Bob Kneller JD, MD, MPH who is working at the University of Tokyo, Research Center for Advanced Science and Technology. Bob took the bGeigie system when he drove up end May to Miyagi Prefecture. Here is his report and findings including pictures of radiation level and the destruction he saw along the Miyagi coastline
The radiation level maps can be found here: Tokyo – Chiba / Chiba – Sendai / Sendai, Ichinoseki, Rikuzentakata, Kesennuma (note – the radiation levels in the report are in Counts Per Minute (CPM) – 300 CPM is equivalent to around 1µSv/hr or 11,000 Bq/m2)
I heard about Safecast from Dorothy Parvaz’s April article “Crowdsourcing Japan’s radiation levels in Al Jazeera”. First I contacted Marcelino Alvarez, who put me in touch with Pieter Franken. I met Pieter when I traveled to Tokyo in mid-May (my work takes me back and forth between Japan and the San Francisco area). Pieter put me in touch with Joe Moross who set my car up with the bBeigie system.
On May 25 I headed north along the Touhoku Expressway for Sendai. South of Koriyama I began to stop at highway rest stops to take hand held readings. The first such rest stop was Abukuma Parking Area. The first reading, 2942 cpm, was with the Geiger counter placed on a weather-worn bench. This was 1000-2000 cpms higher than pavement readings in the same rest stop.
The same phenomenon occurred at the Asaka Rest Stop, just south of the Koriyama interchange. There a worn bench reading was 7195 cpm (image 0590 attached) which was over twice the pavement reading.
The highest reading I recorded was at the next rest stop, the Adatara Service Area. Again a bare wooden bench reading took the prize, 7319 cpm, while the pavement readings were just over 50% of that value. If I recall, the bGeigie mounted about 1.5 meters above the pavement was reading in the 400’s (1.3µSv/hr) at Asaka and Adatara.
This suggests that radioactive isotopes had been absorbed by the bare wood and not washed away (or otherwise dispersed) as it had been on the pavements.
As I went farther north stopping at rest stops, both the bGeigie and hand held Geiger counter readings decreased. At the rest stops just before the exits to Sendai, Zaou and Sugou, pavement readings were 446 and 258 cpm, respectively. By this time I was taking pavement readings almost directly underneath the bGeigie. I noticed that the bGeigie air readings (1.5 m above pavement) were about 1/10th the pavement reading at Zaoo and about 1/5th the reading at Sugou. Maybe the high ratio of pavement:air readings around Koriyama provides a clue as to the relative abundance of principally gamma vs gamma + alpha + beta emitters along the route–in particular the relative abundance of alpha or beta emitters in the areas of highest radioactivity.
Three days later, I drove north to the ports of Ofunato, Rikuzentakada and Kesennuma to see the conditions following the tsunami. I have never before seen such devastation. Parts of Ofunato and Kesennuma remain although the downtown areas near the port are destroyed. But almost all the buildings in Rikuzentakada are gone, save for the sturdy but ravaged Capitol 1000 Hotel near the shore and two apartment blocks, where those who made it to the 5th floor survived. At least the people in this area don’t have to deal with high radioactivity. Readings were low. (But what about the coastal marine food chain and the fish on which the livelihoods of the people in these towns will depend?)
That evening I drove back to Tokyo, reversing the route I had taken north (the Tohoku Expressway) as far as Koriyama, then cutting east to the coast at Iwaki and continuing along the Jouban Expressway to Tokyo. Pavement readings declined as I went east from Koriyama. They were 466 cmp at a rest stop near Iwaki.
By way of background and afterward. From the time I read the Aljazeera article, I was interested in this project. In a previous career as a cancer epidemiologist at the US National Cancer Center, I worked down the hall from John Boice and others in the Radiation Epidemiology Branch. These people who carried out some of the key studies of the health effects of the atomic bombings and Chernobyl. They will be following the health impact of the Fukushima accident. But in addition, it is important to democratize the collection of health data and to empower people affected by health threatening incidents–especially if data from government authorities is unreliable or withheld.
So I hope the project goes forward, and that it involves more and more Japanese people who feel empowered to find monitor their own environment and to make change happen when change is needed. I also hope that the data being gathered will prove useful to the worldwide epidemiology community and that insights about radiation dispersion, health effects, etc will come from this project.