中山 誠健

Volatile organic compounds (VOCs) have been suspected to cause building-related symptoms (BRSs). Although some studies investigated the association between BRSs and VOCs in indoor air, those results were inconsistent. This study investigated the contamination status of VOCs in the indoor air of 154 houses in Japan. Additionally, these samples were grouped by hierarchical clustering analysis based on the VOC composition, and the relationship between a VOC cluster and the BRSs was investigated. The median concentration of the sum of VOCs (ΣVOCs) was 140 μg m-3 (range: 18-3500 μg m-3). The levels of acetaldehyde in four samples and p-dichlorobenzene in one sample exceeded the guideline value. As a result of the hierarchical clustering analysis, the samples in this study were divided into six characteristic clusters based on the VOC composition. The ΣVOCs in cluster 1 were significantly lower than those in other clusters. In cluster 2, acyclic and aromatic hydrocarbons were dominant. Cluster 3 had a relatively high proportion of limonene. In cluster 4, the concentrations and composition ratios of α-pinene were higher than those of other clusters. In cluster 5, p-dichlorobenzene accounted for 42 %-72 % of the total VOCs. Cluster 6 had a relatively high proportion of decamethyl cyclopentasiloxane. This clustering likely depended on the construction of houses and lifestyles. As a result of logistic regression analysis, cluster 5 was associated with the cough symptoms of the BRSs. The results of the present study suggest that investigating the association between VOCs and BRSs is necessary to consider not only total concentrations such as TVOC and ΣVOCs but also VOC composition.

Semi-volatile organic compounds (SVOCs), such as phthalates and organophosphate flame retardants (OPFRs), are used in plastic products and electrical and electronic applications as plasticisers or flame retardants. There has been a growing concern that exposure to SVOCs can have an adverse impact on human health. Several large-scale epidemiological studies employ the sampling of house dust using household vacuum cleaners as the standard method. However, in this method, house dust samples might be contaminated by flame retardants and plasticisers because of the presence of these chemicals in the plastic materials of cleaners. Therefore, this study aimed to develop a low-cost, easy-to-distribute sampling method to collect house dust using a mop and analyse OPFRs, phthalate esters, and alternative plasticisers in house dust. Our findings show that the proposed mop sampling method can be easily distributable and lower contamination from a sampling tool. Moreover, the proposed house dust sampling method is extremely useful for a large-scale survey such as a cohort study.

The indoor environment, particularly indoor air quality (IAQ), is significantly associated with building-related symptoms (BRSs) in humans. In our previous studies, we demonstrated a significant relationship between BRSs and indoor chemical concentrations. In Japan, the Ministry of Health, Labor, and Welfare (MHLW) guideline recommends an air quality target of 13 volatile organic compounds (VOCs) and a provisional target of 400 μg/m3 for total VOCs (TVOC). The objective of this study was to determine the relationship between TVOC levels and the risk of BRSs using the Japanese provisional target TVOC level of 400 μg/m3. The relationship between odor intensity and BRSs while the TVOC levels were under 400 μg/m3 was also examined. The study was conducted in a laboratory house (LH) on the campus of Chiba University from 2017-2019. The study included 149 participants who spent 60 minutes in the LH. The participants were asked to evaluate the IAQ of the LH. A significant relationship between the risk of BRSs and the provisional target TVOC level was observed (odds ratio: 2.94, 95% confidence interval: 1.18-7.35). Furthermore, a significant relationship between odor intensity and risk of BRSs in spaces with TVOC levels less than 400 μg/m3 was detected (odds ratio: 6.06, 95% confidence interval: 1.21-30.44). In conclusion, the risk of BRSs is significantly lower in spaces with low TVOC levels and low odor intensity. Reducing the concentration of airborne chemicals and odor intensity may improve IAQ and prevent BRSs.

The relationship between chemical concentrations in indoor air and the human sense of comfort and relaxation have been reported. We investigated the effect of the sum of volatile organic compounds (sigma VOCs; sum of 79 VOCs) on the level of relaxation in two laboratory houses with almost identical interior and exterior appearances. The electroencephalogram (EEG) was monitored to evaluate the degree of personal relaxation objectively. The experiments were conducted in laboratory houses (LH) A and B with lower and higher levels of sigma VOCs, respectively. A total of 168 healthy volunteers participated, who each performed the task for 20 min, followed by a 10-min break, and EEG was measured during the break. Simultaneously as subjective evaluations, the participants were asked to fill a questionnaire regarding the intensity of odor and preference for the air quality in each LH. The subjective evaluation showed a significant association between sigma VOCs and participants' relaxation (OR: 2.86, 95%CI: 1.24-6.61), and the objective evaluation indicated that the participants were more relaxed in the LH with lower levels of sigma VOCs than that with higher levels (OR: 3.03, 95%CI: 1.23-7.50). Therefore, the reduction of sigma VOCs and odors in indoor air would have an effect, which is the promotion of relaxation.</p>

kkPeople's living environments and lifestyles have drastically changed with the times. It is necessary to reassess risk factors associated with changes in social conditions to prevent sick building syndrome (SBS). This study aimed to determine the association between the onset of SBS and participant characteristics, social and residential environments, and lifestyle. An online nationwide questionnaire survey involving 4996 participants was conducted. The risk factors for SBS were examined using logistic regression analyses. The main risk factors for SBS were female sex (odds ratio [OR] = 1.20, confidence interval [CI] = 1.01-1.42) and young age (OR = 2.42, CI = 1.55-3.78). Other risk factors included having a medical history of allergies and mental illness (OR = 1.75, CI = 1.34-2.29), special housing specifications for the indoor environment (OR = 0.77, CI = 0.63-0.95), smoking indoors (OR = 1.25, CI = 1.00-1.55), and others. Women, young individuals, and those with a history of diseases, such as allergies and mental illness, had an increased risk of SBS, indicating that such individuals need to pay attention to chemical exposure. The study results indicate the possibility of preventing SBS by the careful selection of indoor environments and lifestyle.

It is well known that the indoor environment, particularly indoor air quality (IAQ), has significant effects on building-related symptoms (BRSs) in humans, such as irritation ofmucosalmembranes, headaches, and allergies, such as asthma and atopic dermatitis. In 2017, Chiba University launched the "Chemiless Town Project Phase 3" to investigate the relationship between IAQ and human health. Two laboratory houses (LHs) were built on a university campus inwhich the interiors and exteriors were similar, but the levels of indoor air volatile organic compounds (VOCs) were different. A total of 141 participants evaluated IAQ using their sensory perception. There was a significant relationship between differences in VOC levels and BRSs occurrence (OR: 6.89, 95% CI: 1.40-33.98). It was suggested that people with a medical history of allergies (OR: 5.73, 95% CI: 1.12-29.32) and those with a high sensitivity to chemicals (OR: 8.82, 95% CI: 1.16-67.16) tended to experience BRSs. Thus, when buildings are constructed, people with a history of allergies or with a sensitivity to chemicals may be at high risk to BRSs, and it is important to pay attention to IAQ to prevent BRSs. (C) 2020 The Authors. Published by Elsevier B.V.

Herein, the concentrations of formic acid, acetic acid, and ammonia in samples of indoor air for 47 new houses were measured two weeks after completion. The houses were fabricated with light-gauge steel structures. The measurements were performed in living rooms and bedrooms without furniture and outdoors. Air samples were analyzed using ion chromatography. The mean values were 28 (living room), 30 (bedroom), and 20 mu g m(-3) (outdoor air) for formic acid; 166 (living room), 151 (bedroom), and 51 mu g m(-3) (outdoor air) for acetic acid; and 73 (living room), 76 (bedroom), and 21 mu g m(-3) (outdoor air) for ammonia. The total values of the three substances accounted for 39.4-40.7% of the sum of chemical compound values. The analyzed compounds were indicated by two principal components (PC), PC1 (30.1%) and PC2 (9%), with 39.1% total variance. Formic acid, acetic acid, and ammonia were positively aligned with PC1 and negatively aligned with PC2. Factors such as room temperature, aldehydes, and phthalates were positively aligned with PC1 and negatively aligned with PC2. Furthermore, concentrations of formic acid, acetic acid, and ammonia were significantly and positively correlated with room temperature (p < 0.05).

© 2019, The Author(s). Nowadays, people spend most of their time indoors; thus, the indoor environment greatly affects human health because of exposure to chemicals indoors. Thus, in collaboration with Japanese house builders, a list of building materials having low volatile organic compound concentrations was compiled herein. The air-quality samples from seven newly built houses (seven bedrooms and seven living rooms) were collected and tested for 64 volatile organic compounds and two aldehydes. Air samples were obtained from the house with no furniture or household goods and were sampled 1 week after construction and repeated after a month. Furthermore, the test results with a 2009 survey of indoor air quality in newly constructed houses were compared. One week after construction, the xylene, styrene, toluene, formaldehyde, and ethylbenzene concentrations were less than half the standard guideline values set in Japan. The main substances detected in the samples were 2-butanone, acetone, ethanol, ethyl acetate, butyl acetate, and undecane. The statistical significance of the changes in substance concentrations over time was examined via Wilcoxon signed-rank test. One month after construction, the concentrations of all chemical substances had undergone a statistically significant reduction, except butyl acetate. The median of total volatile organic compounds in living rooms was 291 µg/m3, and the maximum was 354 µg/m3; both were under Japan’s provisional total volatile organic compound target of 400 µg/m3. These values were significantly lower than those recorded by other researchers. This study concludes that using experimentally identified low volatile organic compound materials effectively improves the indoor air quality.

Background: With the aim to prevent sick building syndrome and worsening of allergic symptoms, primarily resulting from the indoor environment, the relationships among people's residential environment in recent years, their lifestyle habits, their awareness, and their symptoms were investigated using an online survey.Methods: In the survey, respondents experiencing symptoms specific to sick building syndrome, although they were not diagnosed with sick building syndrome, were categorized in the pre-sick building syndrome group. The relationships among individual characteristics, residential environment, and individual awareness were analyzed.Results: Results showed that the prevalence of pre-sick building syndrome was high among young (aged 20-29 years) population of both sexes. In addition, "condensation," "moisture," "musty odors" in the house, and the "use of deodorant and fragrance" were all significantly associated with pre-sick building syndrome. Conversely, there was no significant association with recently built "wooden" houses that are highly airtight and have thermal insulation.Conclusions: Efficient "ventilation" plans and "ventilation" improvement and air conditioning systems to prevent mold and condensation in rooms are necessary to maintain a good, indoor environment that is beneficial for health. Efforts should also be made to encourage individuals to regularly clean and effectively ventilate their homes.

Recently, people have become increasingly aware of potential health issues related to indoor environments. In this study, we measure the concentrations of various volatile organic compounds, carbonyl compounds, and semi-volatile organic compounds, as well as the ventilation rates, in 49 new houses with light-gauge steel structures one week after completion. The proper indoor air quality of new residential environments can be ensured by characterizing people's exposure to certain chemicals and assessing future risks. Our results show that the concentrations of the measured compounds were lower than the guideline values set by the Ministry of Health, Labour and Welfare of Japan, and would continue to decrease. However, we observed that unregulated compounds, assumed to be substitutes for regulated solvents, contributed substantially to the total volatile organic compounds. To reduce indoor chemical exposure risks, the concentrations of these unregulated compounds should also be minimized. In addition, their sources need to be identified, and manufacture and use must be monitored. We believe it is important to select low-emission building materials for reducing residents' exposure to indoor chemicals.

© 2018 WIT Press. The relationship between adverse health effects, including sensory irritation and decline in cognitive performance, and the exposure to indoor air pollutants has been considered inconclusive. This is possibly because the occurrence of relevant symptoms seems to largely depend on individual sensitivity and mental state. Therefore, further evaluation of the relationship between indoor environment and its related adverse health effects using subjective and objective data is required. In 2017, two new laboratory houses (LHs) were built on the campus of Chiba University (Japan) as part of a new project called the Chemiless Town Project, phase 3. This project aims to investigate the impact of the indoor environment on physical and mental health and to construct a healthy indoor environment. The interior and exterior appearances of the two LHs appear the same; however, the concentrations of chemicals inside them differ due to the differences in their construction and interior materials. The project commenced in November 2017 and will continue until 2021. In the project, approximately 400 participants will be recruited who will evaluate indoor air using sensory perception. The evaluation will be performed using objective methods, including monitoring brain waves and heart rate variability, and subjective methods, including completing self-reported questionnaires, while staying in each LH. Simultaneously, the indoor air samples of each laboratory will be collected and analysed. In 2017, 17 healthy female and 26 healthy male volunteers participated in the experiment. The median of sum concentrations of volatile organic compounds in the indoor air of each LH were 314 and 1674 μg/m3, respectively. No significant differences were found in terms of degrees of performance and relaxation of participants between the LHs. Additional research and analysis will be conducted with more participants to further examine the relationship between the indoor environment and related health effects.