Haruki Osawa

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.

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

BackgroundPsychosocial 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.MethodsA 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.ResultsAmong 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.ConclusionsImprovements in the physical environmental qualities in an office throughout the year are important along with the reduction in psychological distress related to work.

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.

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.

MANAGEMENT SITUATION OF INDOOR ENVIRONMENT AND HVAC SYSTEM IN FACILITIES FOR THE ELDERLY

Japan has been well on the way to an aging society and entered a super-aged society at 21.5 percent aging rate in 2007, and the facility demand for the elderly is increasing rapidly. However, the actual situation of indoor environment had not been clear because there is not a regulation and control law at all. It is critical to understand the facility managing system and the actual condition of indoor environment in order to improve quality of life such as health and comfort and to prevent infectious diseases in care welfare facilities for the elderly. Cross-sectional study utilizing the questionnaire survey on special nursing homes all over the country was conducted to clarify the management, maintenance and actual condition of indoor environment and building equipment in 2013. As a result, the installation of individual air conditioning equipment expanded countrywide due to benefits such as initial / operating costs and high energy performance. the control criteria of air temperature were set in about 60 percent of the facilities, while those for relative humidity and ventilation were less. Most of the facilities set control criteria for indoor environment factors within commonly-accepted levels, but a problem also was seen in knowledge and recognition of facility managers for HVAC and ventilation system. In order to secure and maintain the favorable indoor environment and hygiene in the elderly facilities, it seems appropriate to remark that a professional administrator should be employed as a facility manager, and they should be educated and provided with the related knowledge and techniques.

Estimation on humidification and ventilation for infection control in residence for the elderly

Purpose / Context - The aim of this study is to clarify an estimation method of humidification for infection control in residences. In Japan indoor humidity is very low in winter especially in recent insulated houses without unvented stoves. Dwellers know that it is necessary to keep humidity ade-quate for infection control, but most of them don’t know the moderate humidity or the effect of venti-lation for infection control. In this study, the state of influenza infection control was evaluated using the measurement results on indoor air in the rooms of six Japanese facilities for the elderly. The temperature is kept better in these residences than that in common Japanese houses. But the humid-ity is quite very low in winter. The energy saving is thought to be one of the causes of this state. Methodology / Approach - Under the assumption that influenza virus generate at a constant rate, the concentrations of survived influenza viruses in indoor air were calculated using an equation, which is given on the basis of the survival tests on influenza virus by G.J.Harper. The equation gives the concentration of influenza viruses using the ventilation rates and absolute humidity. Then an index on virus reduction which integrates ventilation effect and humidity effect was proposed. Results - The energy consumption of ventilation and humidification for infection control is calculated using this index. The results show that it is effective to control ventilation rate for both of infection control and saving energy in many rooms in these facilities. Key Findings / Implications - Effective strategies for infection control in residences are discussed using the index of influenza infection control. Originality - The index of influenza infection control is proposed in this study. This index is useful to estimate indoor air quality. The index is expected to be used for the design of building performances and air conditioning systems.

Measurement of Ventilation Airflow Rates of 39 Houses by Three Different Methods

Abstract This paper reports on the measurement results of ventilation rates in existing occupied houses in the northern region of Japan. A total of 61 measurements were made over a period of 4 years on 39 houses. Some houses were measured once a year over the four years investigation period. The ventilation systems equipped in some of the investigated houses were improved during the course of this investigation period. The effect of the improvement on ventilation airflow volume was reported. The ventilation rates were measured by three different methods, namely constant concentration method, measurement of airflow rate at inlets/outlets and passive homogeneous emission method. Through this investigation, the measurement results indicated that the ventilation rate was insufficient in many houses and some of the ventilation systems were not operated properly. In addition, the amount of air leakage in the house envelope and the amount of air change due to occupant behaviour were also determined.