A forecast by the Comprehensive Nuclear Test Ban Treaty Organization shows how weather patterns this week might disperse radiation from a continuous source in Fukushima, Japan. The forecast does not show actual levels of radiation, but it does allow the organization to estimate when different monitoring stations, marked with small dots, might be able to detect extremely low levels of radiation. Health and nuclear experts emphasize that any plume will be diluted as it travels and, at worst, would have extremely minor health consequences in the United States.

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