One radiated particle in Lungs can be fatal in 20 to 30 years.

This is the one fact you don't hear about much. People usually talk more about external exposure. But, since one radiated particle(say a dust mote) gets lodged in your lungs. Within 20 to 30 years from this one particle in your lungs you likely would be dead. So, if you are in Japan and near the radiation site, one of the ways to live a full life is to wear a gas mask to filter out radiated particles in the air so they don't lodge in your lungs, especially if you need to be outside at all.