Radiation map for Japan

A friend traveling to Japan asked me how safe is there after the Fukushima Nuclear disaster. This is a radiation dose map for Japan. Below, you will find a brief explanation to understand it, based on a Radiation Awareness Module from the Canadian Light Source.

Ionizing radiation is energy transmitted through a media capable to remove electrons from atoms. During its travel, some of its energy is deposited or lost into the medium. If the energy is deposited in a person, he or she receives a radiation dose.  Radiation doses are measured in milli-Sieverts (mSv). The average annual radiation dose to the general population in Canada from natural sources is about 2 mSv per person, and from human-made sources is about 0.6 mSv per person. This is a brief chart of the radiation dose a person can adsorbed from different sources.