Citizen Scientists Reclaim Japans Nuclear Disaster Zone

Every year when winter finally loosens its grip on northern Japan, Tomoko Kobayashi begins what has become an annual rite for her and a small band of collaborators.They head out with measuring devices to keep tabs on an invisible threat that still pollutes the mountains and forests around their homes: radioactivity.In her car, Ms.

Kobayashi follows a route that she now knows by heart, making regular stops to probe the air with a survey meter, a box with a silver wand that looks and acts like a Geiger counter.She uses it to detect gamma rays, a telltale sign of the radioactive particles that escaped when three reactors melted down at the Fukushima Daiichi nuclear plant in March 2011 after an undersea earthquake sent a towering tsunami crashing into the coastline.She and a group of fellow residents of Odaka, a small community 10 miles north of the plant, spend days collecting readings at hundreds of points, which they use to create color-coded maps of radioactivity levels emanating from reactor particles still scattered across the countryside.

Ms.Kobayashi posts them on the wall of her small inn for guests to see, making up for a lack of government maps detailed enough to reveal potentially hazardous spots.“The government wants to proclaim that the accident is over, but it isn’t,” said Ms.

Kobayashi, 72, who reopened her inn, Futabaya, seven years ago, after the evacuation order in Odaka was lifted.The inn has been in her family for four generations and she grew up here, never imagining she would one day have to master an arcane knowledge of microsieverts and atomic half-lives.“I choose to live here, but is it safe? Can I pick these nuts or eat those fruit? The only way to know for sure is do the measuring ourselves,” she said....