In this study, we aimed to investigate radiation risk perception, mental health, and interest in tritiated water among evacuees from and returnees to Tomioka town, Japan, as well as to evaluate the intention to return (ITR) among evacuees living inside and outside Fukushima Prefecture. Of the 1728 respondents, 318 (18.4%) and 1203 (69.6%) participants reported living outside and inside Fukushima Prefecture, and 207 (12.0%) reported living in Tomioka. The ITR was not significantly different between those who lived inside and outside the prefecture among the evacuees. Similarly, there were no significant differences in radiation risk perception, mental health, and interest in tritiated water. However, the evacuees were independently associated with a motivation to learn about tritiated water (OR = 1.242, 95%Cl: 1.041–1.438, p = 0.016), reluctance to consume food from Tomioka (OR = 1.635, 95%Cl: 1.372–1.948, p < 0.001), and concern that adverse health effects would occur because of the Fukushima Daiichi Nuclear Power Plant accident (OR = 1.279, 95%Cl: 1.055–1.550, p = 0.012) compared to returnees, according to logistic regression analysis. Interestingly, the returnees were found to have better mental health but lower life satisfaction than the evacuees. These findings suggest the importance of ongoing risk communication about radiation exposure and tritiated water among residents regardless of their place of residency.

This study aimed to clarify the frequency of visits (FOV) to Tomioka town, Japan, and related factors among evacuees more than a decade after the Fukushima Daiichi Nuclear Power Plant accident. A questionnaire survey was conducted on residents (age ≥ 18 years) who had residence cards in August 2021. Of the 2260 respondents, the FOV to Tomioka was as follows: 926 (41.0%) more than twice a year (Group 1 [G1]), 841 (37.2%) once a year (G2) and 493 (21.8%) no visits (G3). About 70% of the respondents who had decided not to return to Tomioka visited once a year or more. No significant differences in the FOV or radiation risk perception were found between groups. Multinomial logistic regression analysis using G3 as a reference revealed independent associations between living inside Fukushima in G1 (odds ratio [OR] = 5.4, 95% confidence interval [CI]: 4.1–7.3; P &lt; 0.01) and G2 (OR = 2.3, 95% CI: 1.8–3.0, P &lt; 0.01), undecided about returning in G1 (OR = 2.5, 95% CI: 1.9–3.3, P &lt; 0.01), females in G1 (OR = 2.0, 95% CI: 1.6–2.6, P &lt; 0.01) and motivation to learn more about tritiated water in G2 (OR = 1.8, 95% CI: 1.3–2.4, P &lt; 0.01). Overall, 80% of the residents had visited Tomioka within a decade after the accident. These findings suggest the need to continue the effective dissemination of information about the effects of a nuclear accident and the subsequent decommissioning process to evacuees after evacuation orders have been lifted.

Temporal variation and fluctuation in environmental contamination in Futaba town and Okuma town, the location of the Fukushima Daiichi Nuclear Power Plant (FDNPP), were evaluated based on a car-borne survey conducted from October 2021 to November 2022. Although the environmental radioactivity levels in the interim storage facility area (ISF) were higher than those in open areas (i.e., the evacuation-order-lifted areas in Futaba town and the specific reconstruction and regeneration base area [SRRB] in Okuma town), only minor changes were seen in the ambient dose and radiocesium detection rates in the ISF and SRRB, respectively. These findings suggest that such differences may be the result of multiple factors such as physical decay (decreasing factor) and radiocesium resuspension (non-decreasing factor) accompanied by human activity such as traffic and decontamination construction in these areas, in addition to weather conditions such as wind direction. However, the higher radiation exposure doses in the ISF and SRRB were estimated to be at a limited level (lower than the public dose). Therefore, to help ensure the safety and future prosperity of residents and communities in the affected areas around the FDNPP, long-term follow-up monitoring of temporal dose levels during the recovery and reconstruction phases is extremely important.