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Volatile organic compounds (VOCs) are representative indoor air pollutants that negatively affect the human body owing to their toxicity. One of the most promising methods for VOC removal is photocatalytic degradation using TiO2. In this study, the addition of carbon black (CB) and heavy metal nanoparticles (NPs) was investigated to improve the efficiency of a TiO2-based photocatalytic VOC decomposition system combined with ultrasonic atomization and ultraviolet irradiation, as described previously. The addition of CB and Ag NPs significantly improved the degradation efficiency. A comparison with other heavy metal nanoparticles and their respective roles are discussed. [ABSTRACT FROM AUTHOR]

The human behavior has much impact on the infectious desease spreading. The pathogen generation is not uniform for the residential area since the human have some preference on where to be. The purpose of the present study is to evaluate the impact of the human preference on the seat choice behavior on the pathogen concentration. The preference of the seat selections in a train was modelled and the agent simulation was performed in order to evaluate the non-uniformity of pathogen. The concentration was calculated with Wells-Riley model. The results of the agent simulation showed the preference of seat choice based on the experimental results in a train environment. The seats at the end were more selected than other seats. The concentration at the seats at the end kept increasing because the agent sat there by turns and that is why there was no recovery time. The double effect of the more seat selection and the less recovery time has much impact on the non-uniformity of the concentration.

In recent years, as houses have become more insulated and airtight, indoor environments in Japan have tended to become low-humidity in winter, making dryness a problem. The relationship between the perception of dryness indoors and low indoor humidity is unclear, though it has been suggested that other environmental factors may influence perception of dryness and adverse health effects. It is essential to clarify the association between the indoor environment and human responses related to the perception of dryness. A questionnaire survey regarding indoor thermal environment, air quality, living environment, resident characteristics, resident behaviour, and health-related symptoms was conducted throughout Japan in the winter of 2022. The paper first describes the findings of this survey on resident characteristics, building characteristics, indoor humidity sensation, operating patterns of humidifiers and other devices, and resident health problems related to indoor dryness. Next, multiple regression analysis was used to identify the factors influencing the impact of dryness on health problems at various sites.

Indoor dampness can promote the establishment of microbes in indoor environments, and as such, controlling dampness is important for maintaining a healthy indoor environment. Here, an index is proposed for evaluating indoor dampness based on checking for visible condensation, mold in living rooms and bedrooms, and moldy odors indoors. In this evaluation method, eight items related to visible condensation, presence of mold, and moldy odors are assigned a maximum score of 3 points; the total score (a maximum of 24 points) is then used as an index for the degree of dampness. We classified the total score into four rankings based on quartiles. Rank 4 represents the lowest rank and was assigned to houses that had the most severe levels of indoor dampness. We hypothesized that the lower the rank, the higher the incidence of sick housing syndrome (SHS) would be among young children. To clarify whether there was an association between child SHS and indoor dampness, we conducted an Internet-based cross-sectional survey on children aged 4–12 years. This study first identified potential confounding variables for exposure to indoor dampness using a directed acyclic graph. The results indicated that the higher the degree of dampness, the higher the health risk was for ocular, nasal, and throat symptoms. Dose-response relationships between indoor dampness and SHS were presented using the dampness index proposed in this study.

COVID‐19 outbreaks occurred in several hospitals, and the National Institute of Infectious Diseases, local authorities, and universities carried out investigations into ventilation in hospitals. The results indicated that ventilation performance was insufficient to prevent aerosol infection due to poor air conditioning, equipment maintenance, and existing ventilation design guidelines. The authors investigated guidelines for ventilation measures for general patient wards with the cooperation of The Society of Air‐Conditioning and Sanitary Engineers of Japan and the Japanese Society for Infection Prevention and Control. Based on a survey of COVID‐19 outbreaks in hospitals, ventilation countermeasure plans for 3 stages (a. normal conditions, b. increased risk of outbreaks, and c. infected patients treated) were compiled. [ABSTRACT FROM AUTHOR]

The characterization of indoor PM2.5 has been concerned about health effects. PM2.5 in indoor air is affected by not only indoor emissions but also penetrations from outdoor air. Therefore, it is important for indoor PM2.5 to take into account of penetration factors of PM2.5 through air conditioning units in buildings. This study aimed at investigating PM2.5 concentrations and I/O ratios (indoor/outdoor concentration) in office buildings. As a result, the relationships between PM2.5 concentrations or I/O ratios and building characteristics could be classified as the types of buildings, such as specific or non-specific, and air conditioning units, such as the individual or central system. The I/O ratio for the specific buildings, over 3,000 m2 of total floor area and buildings that had the central air conditioning unit was relatively low because of medium performance filter in air conditioning units.