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.

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.

[New Scientific Evidence-based Public Health Guidelines and Practical Manual for Prevention of Sick House Syndrome].

Recently, we have published a book containing evidence-based public health guidelines and a practical manual for the prevention of sick house syndrome. The manual is available through the homepage of the Ministry of Health, Labour and Welfare (http://www.mhlw.go.jp/file/06-Seisakujouhou-11130500-Shokuhinanzenbu/0000155147.pdf). It is an almost completely revised version of the 2009 version. The coauthors are 13 specialists in environmental epidemiology, exposure sciences, architecture, and risk communication. Since the 1970s, health problems caused by indoor chemicals, biological pollution, poor temperature control, humidity, and others in office buildings have been recognized as sick building syndrome (SBS) in Western countries, but in Japan it was not until the 1990s that people living in new or renovated homes started to describe a variety of nonspecific subjective symptoms such as eye, nose, and throat irritation, headache, and general fatigue. These symptoms resembled SBS and were designated "sick house syndrome (SHS)." To determine the strategy for prevention of SHS, we conducted a nationwide epidemiological study in six cities from 2003-2013 by randomly sampling 5,709 newly built houses. As a result 1,479 residents in 425 households agreed to environmental monitoring for indoor aldehydes and volatile organic compounds (VOCs). After adjustment for possible risk factors, some VOCs and formaldehyde were dose-dependently shown to be significant risk factors. We also studied the dampness of the houses, fungi, allergies, and others. This book is fully based on the scientific evidence collected through these studies and other newly obtained information, especially from the aspect of architectural engineering. In addition to SHS, we included chapters on recent information about "multi-chemical sensitivity."

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.