Safecast s a global volunter-centered citizen science project working to empower people with data about their environments. It was established by Sean Bonner, Pieter Franken and Joi Ito shortly after the Fukushima Daiichi nuclear disaster in Japan, following the Tohoku earthquake on 11 March 2011 and manages a global open data network for ionizing radiation monitoring.
Azby Brown et al, 2016 Safecast: successful citizen-science for radiation measurement and communication after Fukushima, J. Radiological Protection, 36, S82.
The Safecast team, with help of International Medcom, Tokyo Hackerspace and other volunteers, has designed various devices for radiation mapping. These include the bGeigie and bGeigie Nano for mobile applications (carborne and walking measurements) as well as fixed stations called Pointcast.
Safecast maintains the largest open dataset of background radiation measurements ever collected. Over 50 million readings to date and growing daily.