Volunteer report: Safecasting Miyagi by Rob Kneller

[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.
この報告は、東京大学先端科学技術研究センター教授のロバート・ケネラーさん(通称ボブさん)によるゲスト投稿です。ボブさんは5月末に車で宮城県を訪れた際に bGeigie 装置を搭載し計測してくださいました。ボブさんによる報告、放射線レベルおよび宮城県沿岸で見た被害の写真を以下に掲載します。
放射線レベルのマップはここで見ることができます:東京 – 千葉千葉 – 仙台仙台、一関、陸前高田、気仙沼(注:報告で使用されている放射線レベルの単位はカウント・パー・ミニット(CPM)です。300CPMはおよそ毎時1マイクロシーベルト、1平方メートルあたり11,000ベクレルに相当します。)
セーフキャストについては、Dorothy Parvaz 氏による4月のアルジャジーラ記事「Crowdsourcing Japan’s radiation levels(日本の放射線レベルをクラウドソーシング)」で読みました。まず Marcelino Alvarez 氏に連絡を取り、同氏がピーテル・フランケン氏を紹介してくれました。私は5月半ばに東京を訪れた際(仕事で日本とサンフランシスコを行き来するため)、ピーテルと会いました。ピーテルから紹介された Joe Moross 氏が、bGeiege 装置を私の車に搭載してくれました。

最も高い数値が計測されたのは次に立ち寄った安達太良サービスエリアでした。ここでもむき出しになった木のベンチの数値が高く7319CPMで、舗道での測定値はこの半分強でした。舗道から1.5メートルの高さに設置された bGeigie の測定値は、安積と安達太良では確か400CPM台(毎時1.3マイクロシーベルト)だったと記憶しています。

パーキングエリアに立ち寄りながらさらに北に進むうち、bGeigie と持ち歩き用のガイガーカウンターともに測定値が下がりました。仙台の出口前のパーキングエリアである蔵王PAと菅生PAでは、舗道の測定値はそれぞれ446CPMと258CPMでした。この頃には私は舗道の測定を bGeigie のほぼ真下で行っていました。蔵王では、bGeigie による空中の数値(舗道表面から1.5メートルの高さ)は舗道の測定値の約10分の1、菅生では約5分の1でした。郡山周辺での高い「舗道の値」対「空中の値」の割合は、沿道における「主にガンマ放射体」と、「ガンマ、アルファ、ベータ放射体の合計」の相対存在量――特に放射能が最も高い地域での、アルファまたはベータ放射体の相対存在量――を知る手がかりを与えてくれるのかもしれません。

今回の背景とその後について。アルジャジーラの記事を読んで以来、私はこのプロジェクトに関心を抱いていました。米国国立衛生研究所がんセンターで疫学研究に携わっていた際、放射線疫学部の John Boice 氏などがすぐ近くで働いていました。彼らは原爆およびチェルノブイリ事故の健康への影響について重要な研究を行った人々です。彼らは福島の原発事故の健康への影響についても追跡調査することにしています。また、特に政府当局からのデータが信頼できない、または公表されない場合、健康に関するデータ収集を民主化し、健康を脅かす出来事の被害を受けた人々に力を与えることが重要です。