Health considerations in Tokyo

britinjapan

Could anyone help out on heath related concerns of radiation exposure by living in Tokyo?

I am particularly sensitive between the difference of internal and external contamination. Assuming that the two main sources of internal contamination are eating and breathing, and one can control what you can eat (by avoiding food from the contaminated zones and lets say drinking imported water), to what extent is one exposed to radiation in the air?

I`ve read that radionuclides don't dissipate by themselves, but cling onto particles - is this correct? Does a simple paper mask protect oneself?

To what extent is the risk in Tokyo and how can one protect oneself further?

Many thanks for any views and suggestions.