22 , 2015-07 , The Institute of Social and Economic Research, Osaka University
Based on prefecture-level panel data from Japan for the period 2010–2014, this study investigates the influence of the 2011 Fukushima nuclear accident on the body mass index (BMI) and obesity rates of children and any changes over time. A differences-in-differences approach was used to show that: (1) BMI and obesity rates in disaster-damaged areas are higher than those in other areas; (2) The difference in the BMI (and obesity rate) of children between damaged and other areas increased after the accident, suggesting that the accident led to increases in both BMI and obesity rates; (3) For cohorts aged between 5 and 7 years old in 2010, the influence of the accident is persistent even after 3 years. Furthermore, the effect of the accident increased as time passed; (4) Cohorts aged between 8 and 10 years in 2010 were no longer influenced by the accident 2 years afterwards. These findings suggest that restrictions placed on outdoor exercise as a result of the nuclear accident in Fukushima prevented younger primary school children from burning calories. Consequently, younger children developed a habit of inactivity, leading a persistent increase in BMI. In contrast, such a habit was not formed by older children and therefore the effect of the accident was temporary.