The Great East Japan Earthquake had occurred on March 11th in 2011. There were serious damages in Tohoku and Kanto district, especially seaside cities of the Pacific Ocean in Tohoku district by tsunami. Many people in these areas had lost their houses and more than fifty thousand temporary houses were built in three prefectures of the Tohoku district. Several problems, such as indoor thermal environment and indoor air quality as well as sound environment problems might be occurred in temporary houses.
This study aimed to investigate the indoor air quality, especially indoor VOC (volatile organic compound) concentrations in the temporary residential houses. In summer in 2011 and winter in 2012, measurements have been conducted in the temporary houses in Sendai and measuring results were compared with guideline value in Japan.
As a result, the mean concentrations were much less than the guideline values, however acetaldehyde, p-dichloro benzene and tetra-decane concentrations in some rooms exceeded the guideline values. Since p-dichloro benzene was emitted from moth-repellent that the residents used, the concentrations in the houses using moth-repellent might become at high level. The α-pinene and d-limonene are emitted from wood materials along with acetaldehyde. Therefore, the reason why the acetaldehyde concentrations were high in indoor air was the emission from woods used as construction and interior materials in the temporary houses. One of the sources of 2-ethyl-1-hexanol in indoor environments is the chemical reaction of the plasticizer contained in vinyl chloride materials. Since the vinyl chloride sheets were used at kitchen floorings in some temporary houses, 2-ethyl-1-hexanol was detected in the specific houses.
TVOC concentrations in every temporary houses exceeded the tentative guideline, 400 μg/m3. Since only about 65% residents of the temporary houses did not generally use the ventilation fans of the toilet or bathroom from the other previous survey, the necessary ventilation air volumes in houses were usually not enough. The acetaldehyde exceeded ratio for the temporary houses was higher than one of the previous survey of newly built houses. The mean TVOC concentration of about 2000 μg/m3 showed higher compared with the tentative guideline value. The shortage of ventilation air volume could be also one of the reasons that the TVOC concentrations were high in the temporary houses. The TVOC in the temporary houses contained not only terpens, such as α-pinene and d-limonene, but also the aromatic hydrocarbons, aliphatic hydrocarbons and other many kinds of compounds.
The mean DEHP concentration in house-hold dust was about 2000 μg/g. In the previous survey of the 30 apartments and kindergartens, an average DBP was 55.6 μg/g, and DEHP was 775.5 μg/g. While DBP concentration was at same level, DEHP was much higher than the previous study. Various materials, such as wooden flooring, tatami, and PVC sheet, are used in the temporary houses, and there were various sources of SVOC. The SVOC concentration in settled dust in the temporary houses could be affected by not only the emission source of interior materials but also the duration of exposure and frequency of cleaning on floorings.
