Spatial and temporal indoor temperature differences at home and perceived coldness in winter: A cross-sectional analysis of the nationwide Smart Wellness Housing survey in Japan.

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. Results showed substantial temperature differences between rooms (horizontal differences): 3.8 °C between living and changing rooms, and 4.1 °C between living rooms and bedrooms. The average vertical and diel (evening-morning) temperature differences in the living room were 3.1 °C and 3.0 °C, respectively. Regional analysis revealed that the Tohoku region experienced larger horizontal and diel indoor temperature differences, primarily due to its practice of intermittent and partial heating in living rooms only, in contrast to Hokkaido's approach of heating the entire house continuously. Despite Hokkaido's comprehensive heating system, it exhibited the largest vertical temperature difference of 5.1 °C in living rooms, highlighting the insufficiency of heating alone and the necessity for enhanced thermal insulation. The multivariate logistic regression analyses showed that average temperatures and vertical temperature differences were associated with perceived coldness, while horizontal and diel differences did not show a significant association, further emphasizing the importance of improved thermal insulation. Moreover, factors like individual attributes (age and gender), and lifestyle choices (meal quantity, exercise habits, alcohol consumption, and clothing amount) were significantly associated with coldness perception. Notably, older adults were less likely to perceive coldness but more vulnerable to the health impacts of low temperatures, underscoring the necessity of not solely relying on human perception for indoor temperature management to protect cold-related health problems.

Operator-derived particles and falling bacteria in biosafety cabinets.

Introduction: To ensure the sterility of cell products that cannot undergo conventional sterilization processes, it is imperative to establish and maintain a clean room environment, regulated through environmental monitoring, including particle counts. Nevertheless, the impact of particles generated by operators as potential contaminants remains uncertain. Thus, in this study, we conducted an accelerated test to assess the correlation between particles generated by operators and airborne bacteria, utilizing biosafety cabinets within a typical laboratory setting. These biosafety cabinets create a controlled environment with air conditioning and high-efficiency particulate air (HEPA) filters, offering fundamental data relevant to cell production. Materials and methods: We conducted a simulation followed by real-time experiments involving human operations to explore the quantity of particles, particle sizes, and the percentage of bacteria within these particles. This investigation focused on conditions with heightened particle generation from operators within a biosafety cabinet. The experiment was conducted on operators wearing textile and non-woven dustless clothing within biosafety cabinets. It entailed tapping the upper arms for a duration of 2 min. Results: Observations under biosafety cabinet-off conditions revealed the presence of various particles and falling bacteria in textile clothing. In contrast, no particles or falling bacteria were detected in operators wearing dustless clothing within biosafety cabinets. Notably, a correlation between 5 µm particles and colony-forming units in textile clothing was identified through this analysis. The ratio of falling bacteria to the total number of particles within the biosafety cabinet was 0.8 ± 0.5 % for textile clothing, while it was significantly lower at 0.04 ± 0.2 % for dustless clothing. Conclusion: This study demonstrated that the number of particles and falling bacteria varied depending on the type of clothing and that quantitative data could be used to identify risks and provide basic data for operator education and evidence-based control methods in aseptic manufacturing areas. Although, this study aims to serve as an accelerated test operating under worst-case conditions, the results need to make sure the study range in general research.

Volatile organic compounds and ionic substances contamination in cell processing facilities during rest period; a preliminary assessment of exposure to cell processing operators.

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 CH3COO- generated from peracetic acid, nitrogen oxides (NOx) and sulfur oxides (SOx) from outdoor environment are also known to pollute air. Therefore, our objective was to assess the air quality in CPFs and detect volatile organic compounds (VOCs) from disinfectants and building materials, and airborne ionic substances from outdoor air. Methods: Sampling was conducted at three CPFs: two located in medical institutions and one located at a different institution. Air samples were collected using a flow pump. Ion chromatographic analysis of the anionic and cationic compounds was performed. For VOC analysis, a thermal desorption analyzer coupled with capillary gas chromatograph and flame ionization detector was used. Results: Analysis of the ionic substances showed that Cl-, NOx, and SOx, which were detected in large amounts in the outdoor air, were relatively less in the CPFs. Ethanol was detected as the main component in the VOC analysis. Toluene was detected at all sampling points. As compared to the other environments, air in the incubator contained larger amounts of VOCs, that included siloxane, tetradecane, and aromatics. Conclusions: No VOCs or ionic substances of immediate concern to the health of the CPOs were detected during the non-operating period. However, new clinical trials of cell products are currently underway in Japan, and a variety of new cell products are expected to be approved. With an increase in cell processing, health risks to CPOs that have not been considered previously, may become apparent. We should continue to prepare for the future expansion of the industry using a scientific approach to collect various pieces of information and make it publicly available to build a database.

Evaluation of shields and ventilation as a countermeasure to protect bus drivers from infection.

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. When a shield, such as acrylic boards or polyvinyl chloride (PVC) sheets, was used as the countermeasure, the deposition of artificial droplets (>4 µm), emitted from beside or behind the driver, on his eyes, mouth, and cheeks reduced by two to three orders of magnitude or more. Deposition on the surfaces around the driver was also reduced following the use of shields. For artificial droplet nuclei (1.3 µm of polystyrene latex (PSL)) emitted from atomizers beside the driver, the operation of the ventilation fan (VF) and air conditioner (AC), and defroster (DEF) greatly reduced the driver's exposure, while the use of the shield did not. The infection risk of the driver was estimated through exposure to the virus via transfer to the mucosa via hands or surface-to-finger, direct adhesion on the mucosa, and direct inhalation of droplets and droplet nuclei. This is under the assumption that the droplets and droplet nuclei measured in this study are 40% the diameter of those after immediately leaving the mouth of the infected person and are constant regardless of particle size. When using the shield, total infection risk via droplet, airborne, and contact transmission was decreased by 75.0-99.8%. When the shield was not installed, the infection risk decreased by 9.74-48.7% with the operation of the VF, AC, and/or DEF.

A longitudinal study on the effects of hygro-thermal conditions and indoor air pollutants on building-related symptoms in office buildings.

We conducted a longitudinal epidemiological study for over 1 year in Tokyo and Osaka, Japan, beginning June 2015, to examine the association between indoor environmental factors and building-related symptoms (BRSs) in office workers. Data were obtained from 483 subjects (225 females and 258 males) in 24 office rooms in 11 office buildings. Environmental monitoring was conducted for hygro-thermal conditions and carbon dioxide and sampling was performed for indoor air pollutants. Questionnaires were concurrently administered to collect information on participants' perceptions of their comfort and health and the conditions of the work environments. Multivariable analyses revealed that upper respiratory symptoms were significantly correlated with a decrease in both relative [odds ratio (OR): 0.77; 95% confidence intervals (CI): 0.62-0.95; p = 0.014] and absolute humidity (OR: 0.89; 95% CI: 0.81-0.97; p = 0.008). Statistically, significant evidence was found that average relative humidity of <38% (OR: 2.68; 95% CI: 1.36-5.27; p = 0.004) showed the most significant association with increased risk of upper respiratory symptoms. Air concentrations of carbon dioxide showed no significant correlation with BRSs at mean concentrations <1000 ppm in most buildings surveyed. Most indoor air pollutant concentrations were relatively low or lower than the values set by indoor air quality guidelines and the values of thresholds for sensory irritation. Air concentrations of indoor air pollutants showed no significant correlation with BRSs. Our data emphasize the importance of appropriate humidity control during low humidity in winter.

Air exchange rates and advection-diffusion of CO2 and aerosols in a route bus for evaluation of infection risk.

As COVID-19 continues to spread, infection risk on public transport is concerning. Air exchange rates (ACH) and advection-diffusion of CO2 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. With two open windows, ACH was greater when a front and rear window were open than when two rear windows were open. With both front and rear ventilation fans set to exhaust, ACH was more than double that when both were set to supply. With air conditioning (AC) off, CO2 and particles spread proportionally at the same rate from a source, whereas with the AC on, the spread rate of particles was about half that of CO2 , because particles might be trapped by a prefilter on the AC unit. Infection risk can be reduced by equipping AC unit with an appropriate filter. Calculations with a modified Wells-Riley equation showed that average infection risk was reduced by 92% in the moving bus with windows open comparing to with windows closed. When the bus was moving with windows closed, exhaust fan operation reduced the average risk by 35%.

Work productivity in the office and at home during the COVID-19 pandemic: A cross-sectional analysis of office workers in Japan.

The coronavirus disease 2019 (COVID-19) pandemic has drastically changed work styles and environments. Given the coexistence of work in the office and work from home (WFH) in the future, studies are needed to identify ways to increase productivity when working in both places. We conducted a questionnaire survey and environment measurements of 916 workers in 22 offices across 2 weeks in November-December 2020 in Japan. While average workdays at the offices decreased from 4.9 to 3.9 days/week, those at homes increased from 0.1 to 1.1 days/week due to COVID-19, indicating an increase in the relative importance of WFH. Compared to the office, the satisfaction rate was lower for lighting, spatial, and information technology (IT) environments, but higher for thermal, air, and sound environments at home. Although it was easier to concentrate on work and to refresh at home, workers experienced challenges associated with business communication from home. Meanwhile, in the office, satisfaction with COVID-19 countermeasures was significantly associated with work productivity. Furthermore, lower PM2.5 concentration was associated with greater satisfaction with COVID-19 countermeasures, indicating that reducing PM2.5 may increase satisfaction with COVID-19 countermeasures and work productivity. We expect these findings will help improve work productivity in the New Normal era.

Survey of air exchange rates and evaluation of airborne infection risk of COVID-19 on commuter trains.

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 (0.23-0.78/h at 0 m2, windows closed to 2.1-10/h at 2.86 m2, fully open). The air exchange rates were one order of magnitude higher when doors were open than when closed. With doors closed, the air exchange rates were higher when the centralized air conditioning (AC) and crossflow fan systems (fan) were on than when off. The air exchange rates in moving trains increased as train speed increased, from 10/h at 20 km/h to 42/h at 57 km/h. Air exchange rates did not differ significantly between empty cars and those filled with 230 mannequins representing commuters. The air exchange rates were lower during aboveground operation than during underground. Assuming that 30-300 passengers travel in a train car for 7-60 min and that the community infection rate is 0.0050-0.30%, we estimated that commuters' infection risk on trains was reduced by 91-94% when all 12 windows were opened (to a height of 10 cm) and the AC/fan was on compared with that when windows were closed and the AC/fan was off.

Environmental factors involved in SARS-CoV-2 transmission: effect and role of indoor environmental quality in the strategy for COVID-19 infection control.

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. This article summarizes the environmental factors involved in SARS-CoV-2 transmission, including a strategy to prevent SARS-CoV-2 transmission in a building environment. SARS-CoV-2 can persist on surfaces of fomites for at least 3 days depending on the conditions. If SARS-CoV-2 is aerosolized intentionally, it is stable for at least several hours. SARS-CoV-2 is inactivated rapidly on surfaces with sunlight. Close-contact aerosol transmission through smaller aerosolized particles is likely to be combined with respiratory droplets and contact transmission in a confined, crowded, and poorly ventilated indoor environment, as suggested by some cluster cases. Although evidence of the effect of aerosol transmission is limited and uncertainty remains, adequate preventive measures to control indoor environmental quality are required, based on a precautionary approach, because COVID-19 has caused serious global damages to public health, community, and the social economy. The expert panel for COVID-19 in Japan has focused on the "3 Cs," namely, "closed spaces with poor ventilation," "crowded spaces with many people," and "close contact." In addition, the Ministry of Health, Labour and Welfare of Japan has been recommending adequate ventilation in all closed spaces in accordance with the existing standards of the Law for Maintenance of Sanitation in Buildings as one of the initial political actions to prevent the spread of COVID-19. However, specific standards for indoor environmental quality control have not been recommended and many scientific uncertainties remain regarding the infection dynamics and mode of SARS-CoV-2 transmission in closed indoor spaces. Further research and evaluation are required regarding the effect and role of indoor environmental quality control, especially ventilation.

Impact of climate and ambient air pollution on the epidemic growth during COVID-19 outbreak in Japan.

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. We analyzed data obtained from March 13 to April 6, 2020, before the Japanese government declared a state of emergency. The results revealed that the epidemic growth of COVID-19 was significantly associated with increase in daily temperature or sunshine hours. This suggests that an increase in person-to-person contact due to increased outing activities on a warm and/or sunny day might promote the transmission of COVID-19. Our results also suggested that short-term exposure to suspended particles might influence respiratory infections caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Further research by well-designed or well-controlled study models is required to ascertain this effect. Our findings suggest that weather has an indirect role in the transmission of COVID-19 and that daily adequate preventive behavior decreases the transmission.

Effects of low-level inhalation exposure to carbon dioxide in indoor environments: A short review on human health and psychomotor performance.

Scientific literature and documents pertaining to the effects of inhalation exposure to carbon dioxide (CO2) on human health and psychomotor performance were reviewed. Linear physiological changes in circulatory, cardiovascular, and autonomic systems on exposure to CO2 at concentrations ranging from 500 to 5000 ppm were evident. Human experimental studies have suggested that short-term CO2 exposure beginning at 1000 ppm affects cognitive performances including decision making and problem resolution. Changes in autonomic systems due to low-level exposure to CO2 may involve these effects. Further research on the long-term effects of low-level CO2 exposure on the autonomic system is required. Numerous epidemiological studies indicate an association between low-level exposure to CO2 beginning at 700 ppm and building-related symptoms. Respiratory symptoms have been indicated in children exposed to indoor CO2 concentrations higher than 1000 ppm. However, other indoor comorbid pollutants are possibly involved in such effects. In the context of significant linear increase of globally ambient CO2 concentration caused by anthropogenic activities and sources, reducing indoor CO2 levels by ventilation with ambient air represents an increase in energy consumption in an air-conditioned building. For the efficient energy control of CO2 intruding a building from ambient air, the rise of atmospheric CO2 concentration needs to be urgently suppressed.

Common SVOCs in house dust from urban dwellings with schoolchildren in six typical cities of China and associated non-dietary exposure and health risk assessment.

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. Based on measured concentrations, schoolchildren's non-dietary exposures to DBP and DEHP at homes are estimated. Due to a longer time spent in child's bedrooms, children's non-dietary exposures to phthalates in child's bedrooms are greatly higher than that in living rooms. As for DBP non-dietary exposure, the most significant pathway is dermal absorption from air, accounting for >70%, whereas, the most predominant pathway for DEHP non-dietary exposure is dust ingestion, contributing from 61.5% to 91.9%. Based on estimated exposure doses, child-specific reproductive and cancer risk are assessed by comparing the exposure doses with DBP and DEHP benchmarks specified in California's Proposition 65. Owing to the high DBP exposure, nearly all of target schoolchildren appear to have a severe reproductive risk, although only non-dietary exposures at home are considered in this study. The average risk quotient of DBP exposure for child-specific MADL in all cities is 31.27 in winter and 10.35 in summer. Also, some schoolchildren are confronted with potential carcinogenic risk, because DEHP exposure exceeds child-specific NSRLs. The maximum DEHP exposure exceeds the cancer benchmark by over 6 times. These results also indicate that controlling indoor phthalates pollution at home is urgent to ensure the healthy development of children in China.

Physicochemical risk factors for building-related symptoms in air-conditioned office buildings: Ambient particles and combined exposure to indoor air pollutants.

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. Multivariate analyses revealed that upper respiratory symptoms showed a significant correlation with increased indoor temperature [odds ratio (OR), 1.55; 95% confidence interval (CI), 1.11-2.18] and increased indoor concentration of suspended particles released from the ambient air pollution via air-conditioning systems (OR, 1.31; 95% CI, 1.08-1.59) during winter. In particular, smaller particles (particle size>0.3µm), which possibly penetrated through the filter media in air-conditioning systems from ambient air, were correlated with upper respiratory symptoms. The use of high-efficiency particulate air filters in air-conditioning systems and their adequate maintenance may be an urgent solution for reducing the indoor air concentration of submicron particles. Several irritating volatile organic compounds (VOCs) (e.g., formaldehyde, acetaldehyde, ethylbenzene, toluene, and xylenes) that were positively correlated with the indoor air concentration among their VOCs, were associated with upper respiratory symptoms, although their indoor air concentrations were lower than those specified by the indoor air quality guideline. A new approach and strategy for decreasing the potential combined health risks (i.e., additive effect of risks) associated with multiple low-level indoor pollutants that have similar hazardous properties are required.

Evaluating prevalence and risk factors of building-related symptoms among office workers: Seasonal characteristics of symptoms and psychosocial and physical environmental factors.

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. METHODS: A nationwide cross-sectional study was conducted during summer in Japan and seasonal differences between summer and winter were evaluated. Self-administered questionnaires were distributed to 489 offices. Possible risk factors for BRSs associated with the work environment, indoor air quality, and job stressors were examined by multiple regression analyses. RESULTS: Among people having at least one BRS, the prevalence of BRSs in summer (27.8%) was slightly higher than that in winter (24.9%). High prevalence was observed for eye and nasal symptoms related to dryness and general symptoms related to psychological distress in both seasons. Analyses revealed that dryness of air was an important and significant risk factor associated with BRSs, and job stressors were significantly associated with general symptoms in both seasons. Conversely, humidity was a significant risk factor of general symptoms in summer (odds ratio, 1.20; 95% confidence interval, 1.02-1.43). Carpeting, recently painted walls, and unpleasant chemical odors in summer and noise, dust and dirt, and unpleasant odors such as body or food odors in both seasons were significant risk factors for BRSs. CONCLUSIONS: Improvements in the physical environmental qualities in an office throughout the year are important along with the reduction in psychological distress related to work.

Effects of water-damaged homes after flooding: health status of the residents and the environmental risk factors.

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. Indoor dampness and visible mold growth significantly increased in homes with greater flood damage. The incidence of respiratory, dermal, ocular, and nasal symptoms one week after flooding was significantly higher in flooded homes compared with non-flooded homes, the incidence of psychological disorders was significantly high for six months after flooding, and the incidence of post-traumatic stress disorder was significantly high six months after flooding. Significant risk factors for respiratory and nasal symptoms included proximity to industrial and waste incineration plants. Our results suggest that rapid action should be taken after flooding to ensure adequate public health and environmental hygiene in the water-damaged homes.