Aim: This study aimed to identify the experiences and feelings of difficulty during international humanitarian aid of Japanese relief workers based on the length of the mission. Methods: This cross-sectional study was conducted from August through December 2015. Participants were 167 Japanese healthcare workers who participated in an overseas disaster relief mission and were asked to complete a self-administered questionnaire. Feelings of difficulty during the international humanitarian aid were assessed using the Humanitarian Aid Difficulty Scale. Scores on this instrument were evaluated based on mission duration using analysis of covariance with adjustment for sociodemographic status and disaster reliefrelated status. Results: Of the instrument's five subscales, the highest score for all mission duration was for "Culture and Custom". Higher "Culture and Custom" scores and "Cooperation" scores were associated with longer mission duration (p trend: 0.02 and 0.004, respectively). Additionally, the "Infrastructure" score for a medium mission duration was higher than that for a long mission duration (p = 0.001), and the "Cooperation" score for a long mission duration was higher than for a short mission duration (p = 0.02).
Conclusions:The mission duration may be independently associated with an increase or decrease in the negative experiences of Japanese relief workers at an overseas disaster site. Results suggest that it is necessary for Japanese relief workers, who participate in international aid, to further enrich their cross-cultural understanding through education. Moreover, relief organizations should provide comprehensive support that addresses difficulty-related feelings depending on the mission duration.