[mpyne]

> a tiny amount of radiation coming from speck of decaying radioactive material released by Fukushima that is floating around in the air of your office room.

By that logic, we should panic if we inhale the sweet scent of someone eating a banana, or walk by a soy farm with the obvious smell of fertilizer. What people actually never seem to understand is that you live in a world already filled with natural radionuclides, they are not simply buried deep in the Earth's mantle, they are everywhere around us.

What airborne radioactivity is floating in your office from Fukushima, by the way? And what type of radiation does that radioactive contamination emit; alphas and betas would effect local tissue, but neutrons and the much much more common gammas would have their interactions occur over a much much greater volume (possibly outside the body entirely).