Publications by authors named "Naoki Kagi"

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 TiO. In this study, the addition of carbon black (CB) and heavy metal nanoparticles (NPs) was investigated to improve the efficiency of a TiO-based photocatalytic VOC decomposition system combined with ultrasonic atomization and ultraviolet irradiation, as described previously.

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Residents themselves are responsible for controlling their living environment, and their perception of coldness is important to protect their health. Although previous studies examined the association between perceived coldness and indoor temperature, they did not consider the spatial-temporal differences in indoor temperatures. This study, conducted in Japan, measured indoor temperatures in 1,553 houses across several rooms (living room, changing room, and bedroom) and heights (at 1 m above the floor and near the floor) over two weeks and obtained the perceived coldness from 2,793 participants during winter.

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Article Synopsis
  • To ensure the sterility of cell products in clean room environments, a study was conducted to evaluate the correlation between particles generated by laboratory operators and airborne bacteria using biosafety cabinets.
  • The research involved experiments that simulated particle generation from operators wearing different types of clothing and measured the quantity and size of particles, along with the presence of bacteria.
  • The findings indicated that operators in textile clothing showed a higher presence of particles and bacteria compared to those in dustless clothing, highlighting the importance of proper attire in maintaining sterile conditions.
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Introduction: Cell processing operators (CPOs) use a variety of disinfectants that vaporize in the workspace environment. These disinfectants can induce allergic reactions in CPOs, due to their long working hours at cell processing facilities (CPFs). Ionic substances such as CHCOO generated from peracetic acid, nitrogen oxides (NOx) and sulfur oxides (SOx) from outdoor environment are also known to pollute air.

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Article Synopsis
  • A year-long study in Tokyo and Osaka explored how indoor environmental factors affect building-related symptoms in office workers, involving 483 participants across 24 office rooms.
  • The findings showed that low relative and absolute humidity significantly correlated with upper respiratory symptoms, with a relative humidity below 38% notably increasing the risk.
  • Despite monitoring indoor air pollutants, the study found no significant link between air quality and building-related symptoms, highlighting the need for effective humidity control in office environments, particularly during winter.
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We evaluated the deposition of droplets and droplet nuclei-generated by simulated coughing and talking from three points in a bus-on the driver's face and on surfaces around the driver (e.g., the steering wheel), based on whether countermeasures were taken, and assuming that an infected passenger was talking to the driver.

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As COVID-19 continues to spread, infection risk on public transport is concerning. Air exchange rates (ACH) and advection-diffusion of CO and particles were determined in a route bus to evaluate the infection risk. ACH increased with bus speed whether windows were open or closed, and ACH were greater when more windows were open.

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To identify potential countermeasures for coronavirus disease (COVID-19), we determined the air exchange rates in stationary and moving train cars under various conditions in July, August, and December 2020 in Japan. When the doors were closed, the air exchange rates in both stationary and moving trains increased with increasing area of window-opening (0.23-0.

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Article Synopsis
  • The COVID-19 pandemic has transformed work dynamics, leading to a shift from office work to increased work-from-home (WFH) arrangements, with office days decreasing and home workdays rising among Japanese workers.
  • A study involving 916 workers revealed that while home environments were preferred for thermal comfort, air quality, and sound, dissatisfaction with lighting and IT resources was noted compared to office settings.
  • The research indicates that satisfaction with COVID-19 safety measures in the office correlates with productivity, and enhancing air quality could foster better satisfaction and work efficiency in the New Normal era.
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The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a new zoonotic agent that emerged in December 2019, causes coronavirus disease 2019 (COVID-19). This infection can be spread by asymptomatic, presymptomatic, and symptomatic carriers. SARS-CoV-2 spreads primarily via respiratory droplets during close person-to-person contact in a closed space, especially a building.

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Coronavirus disease 2019 (COVID-19) rapidly spread worldwide in the first quarter of 2020 and resulted in a global crisis. Investigation of the potential association of the spread of the COVID-19 infection with climate or ambient air pollution could lead to the development of preventive strategies for disease control. To examine this association, we conducted a longitudinal cohort study of 28 geographical areas of Japan with documented outbreaks of COVID-19.

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Scientific literature and documents pertaining to the effects of inhalation exposure to carbon dioxide (CO) on human health and psychomotor performance were reviewed. Linear physiological changes in circulatory, cardiovascular, and autonomic systems on exposure to CO at concentrations ranging from 500 to 5000 ppm were evident. Human experimental studies have suggested that short-term CO exposure beginning at 1000 ppm affects cognitive performances including decision making and problem resolution.

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This paper presents concentrations of common SVOCs in house dusts from urban dwellings with schoolchildren in six typical Chinese cities in winter and summer. Among the detected SVOCs, DBP and DEHP have a higher detection rate. The levels of these two substances contribute an average proportion of over 90% of the total SVOCs' levels, and show a significant correlation in most cities.

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Background: Psychosocial and environmental factors at the workplace play a significant role in building-related symptoms (BRSs). Environmental factors change during summer cooling and winter heating using air-conditioning systems. Thus, significant risk factors in each season need to be clarified.

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We conducted a cross-sectional epidemiological study to examine the correlation between indoor air quality (IAQ) and building-related symptoms (BRSs) of office workers in air-conditioned office buildings. We investigated 11 offices during winter and 13 offices during summer in 17 buildings with air-conditioning systems in Tokyo, Osaka, and Fukuoka, and we included 107 office workers during winter and 207 office workers during summer. We conducted environmental sampling for evaluating IAQ and concurrently administered self-reported questionnaires to collect information regarding work-related symptoms.

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We evaluated the health status of residents and the environmental risk factors of housing after flooding. Questionnaires were distributed to 595 selected households (one adult resident per household) in six areas in Japan which were severely flooded between 2004 and 2010. A total of 379 responses were obtained.

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