People should check out Safecast, which is a citizen-led open data network for monitoring and publishing radiation readings, including an open API: https://blog.safecast.org/ They're using low-cost open hardware, including Arduino: https://github.com/Safecast/General/wiki/Safecast-Devices Here's their latest heatmap (well, radiation map) for Japan, centered on the Fukushima area: https://safecast.org/tilemap/?y=37.14…
Do you know how they're communicating the expected health effects of dose rates like these? For instance the yellow is 4 uSv/hr, roughly 10x a normal dose rate in the USA.
I don't know that, I'm sorry, but you can e-mail them or Tweet them and find out.