New “loss of happy life expectancy” indicator and its use in risk comparison after Fukushima disaster

To assess the effects of policy measures taken to ensure health and promote well-being, we developed a novel indicator, "loss of happy life expectancy" (LHpLE), under the concept that an objective of life is maximization of lifelong happiness, by using objective survival probabilities and a simple question regarding emotional happiness: "Did you experience a feeling of happiness yesterday yes/no?" We measured the emotional happiness of 4990 Japanese respondents through a questionnaire. We then used LHpLE to compare risks after the 2011 Fukushima disaster. LHpLE due to psychological distress was estimated from a decline of emotional happiness, whereas that due to radiation exposure was assessed from shortened life expectancy caused by additional cancer mortality. LHpLE values due to psychological distress in evacuees were approximately 1 to >2 orders of magnitude higher than those due to cancer mortality caused by actual radiation exposure, highlighting the importance of measures to minimize distress following public health emergencies. LHpLE could be used for integrated risk comparison among different types of harms and therefore in government policy-making.