Tsuji Masayoshi, Kakamu Takeyasu, Hayakawa Takehito, Kumagai Tomohiro, Hidaka Tomoo, Kanda Hideyuki, Fukushima Tetsuhito
Department of Hygiene and Preventive Medicine, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima 960-1295, Japan.
Sangyo Eiseigaku Zasshi. 2013;55(2):53-8. doi: 10.1539/sangyoeisei.b12008. Epub 2013 Mar 5.
Ever since the Fukushima Daiichi nuclear power plant (NPP) accident, every day about 3,000 workers have been working to repair the situation. The frequent occurrence of heat disorders has been a concern for the workers wearing protective clothing with poor ventilation. We have been analyzing the heat disorder problem since the accident in order to come up with a solution to prevent future heat disorder incidents among Fukushima Daiichi NPP accident clean-up workers.
From March 22 to September 16, 2011, the Fukushima Labor Bureau assessed 43 cases of nuclear power plant workers with heat disorders. Age of subject, month and time of occurrence, temperature, and humidity were examined for each case, as well as the severity of heat disorders. The grade of severity was divided into Grade I and Grade II or higher. Then, age, temperature, and humidity were analyzed using the Mann-Whitney Utest, and age, temperature, humidity, and presence or absence of a cool-vest were analyzed using the χ(2) test and logistic regression analysis. SPSS version 17.0 statistical software was used with a level of significance of p< 0.05.
Heat disorders occurred most frequently in subjects in their 40s (30.2%), followed by those in their 30s (25.6%), mostly in July (46.5%) between 7 am and 12 pm (69.8%). Heat disorders occurred most frequently in environments with temperatures more than 25°C (76.7%) and humidity of 70-80% (39.5%). Heat disorders of Grade II or higher occurred in 10 cases, 5 of which were in June. According to statistical analysis, there were no significant differences in difference of severity for all factors.
Heat disorders usually occur in workers aged 45-60; however, cases of heat disorders at the Fukushima Daiichi NPP occurred in clean-up workers at the relatively younger ages of 30-40, suggesting the need for heat disorder prevention measures for these younger workers. Heat disorder cases primarily occurred in the morning, necessitating preventive measures for the early hours of the day. In addition, because heat disorders of Grade II or higher occurred in June in 5 of 10 cases, we believe heat disorder precautions should be implemented from June. The lack of significant difference in severity difference may be attributable to the small number of cases or other factors. We think Fukushima Daiichi NPP accident clean-up workers need heat disorder prevention measures for their safety, based on the results of this study.
自福岛第一核电站事故以来，每天约有3000名工人致力于修复局面。对于穿着通风性差的防护服的工人而言，热紊乱频繁发生一直令人担忧。自事故发生后，我们一直在分析热紊乱问题，以便找到解决方案，防止福岛第一核电站事故清理工人未来发生热紊乱事件。
2011年3月22日至9月16日，福岛劳动局评估了43例患有热紊乱的核电站工人。对每例病例检查了受试者年龄、发生月份和时间、温度、湿度以及热紊乱的严重程度。严重程度等级分为I级和II级及以上。然后，使用曼-惠特尼U检验分析年龄、温度和湿度，并使用χ²检验和逻辑回归分析年龄、温度、湿度以及是否穿着冷却背心。使用SPSS 17.0版统计软件，显著性水平为p<0.05。
热紊乱最常发生在40多岁的受试者中（30.2%），其次是30多岁的受试者（25.6%），大多发生在7月（46.5%）上午7点至中午12点之间（69.8%）。热紊乱最常发生在温度超过25°C（76.7%）且湿度为70 - 80%（39.5%）的环境中。II级及以上的热紊乱发生了10例，其中5例发生在6月。根据统计分析，所有因素在严重程度差异方面均无显著差异。
热紊乱通常发生在45 - 60岁的工人中；然而，福岛第一核电站的热紊乱病例发生在相对年轻的30 - 40岁的清理工人中，这表明需要为这些年轻工人采取热紊乱预防措施。热紊乱病例主要发生在早晨，因此需要针对一天中的早些时候采取预防措施。此外，由于10例中有5例在6月发生了II级及以上的热紊乱，我们认为应从6月开始实施热紊乱预防措施。严重程度差异缺乏显著差异可能归因于病例数量少或其他因素。基于本研究结果，我们认为福岛第一核电站事故清理工人为了自身安全需要热紊乱预防措施。
