In the immediate aftermath of the nuclear accident, public-health experts worried about the possible risk from radiation. Subsequent analyses have shown that the prompt, if frantic, evacuation of areas around the reactors probably limited the public’s exposure to a relatively safe level (see ‘The evacuation zones’). But uncertainty, isolation and fears about radioactivity’s invisible threat are jeopardizing the mental health of the 210,000 residents who fled from the nuclear disaster.

Researchers and clinicians are trying to assess and mitigate the problems, but it is unclear whether the Japanese government has the will, or the money, to provide the necessary support. Nor is it certain that the evacuees will accept any help, given their distrust of the government and their reluctance to discuss mental problems. This combination, researchers fear, could drive up rates of anxiety, substance abuse and depression.