The Great East Japan Earthquake occurred on March 11, 2011, causing severe damage to cities in the Tohoku district along the coast of the Pacific Ocean. Many people in the Tohoku area lost their homes, and as a result, more than 50,000 temporary housing units were built in three affected prefectures. Most temporary housing units were terrace houses built closely together with subpar thermal insulation and energy conservation, so potential problems concerning indoor thermal and acoustic environments, as well as the air quality, are a serious concern. Therefore, the objective of the present study was to clarify the relationship between the indoor and outdoor environment of temporary housing and the overall living situation of temporary housing residents. We also sought to propose an optimal method for the environmental design of temporary housing and to suggest ways to improve environmental policies.
We conducted a questionnaire survey regarding the environmental factors and self-reported health conditions of residents living in temporary housing in and around Sendai city in the summer of 2011 and the winter of 2012. Questionnaires were distributed by mail to 99 temporary housing units in the summer and 152 in the winter, with response rates of 77.8% and 57.9%, respectively. In addition, we performed multivariable logistic regression analysis to investigate the association between adverse health effects and influencing factors related to living in temporary housing.
Based on the results, 78.7% of the respondents answered that there was visible condensation on the surfaces of doors and windows, and 46.6% answered that they had observed mold growth in the winter. About 40% of the respondents reported that they used exhaust fans in the lavatory or bathroom continuously for ventilation. On the other hand, about half of the respondents only used exhaust fans when using the toilet or taking a bath. These results suggest that air circulation and ventilation are inadequate in temporary housing.
The questionnaires also included items regarding the following health-related symptoms: ocular symptoms, nasal symptoms, respiratory symptoms, dermal symptoms and mental symptoms. The results showed that the prevalence of each symptom was about 40%, and that symptom onset was within 3 months after moving into the temporary housing. Adjusted odds ratios for each health symptom in the summer and winter were calculated using a multivariable logistic regression model adjusted for age, gender, and smoking status. In the summer, the risk of ocular, nasal, respiratory and dermal symptoms increased significantly with closer proximity to industrial plants (p<0.05). In the winter, the risk of nasal, respiratory, and dermal symptoms increased significantly with increased frequency of hanging the laundry indoors (p<0.05). These results suggest that among residents of temporary housing, the outdoor air environment is associated with health symptoms during the summer and the indoor air environment is associated with adverse health effects during the winter.
