Relationship between human behavior and indoor air quality of private room in a care facility for the elderly in Japan

In Japan, the number of elderly people in need of nursing care is increasing while the population of young people is decreasing, and the potential for labor shortages in the field of elder care is of great concern. This study aimed to estimate the behavior of the elderly by using sensors to monitor indoor air quality (IAQ), without placing undue burden on the elderly or their caregivers. Odor and carbon dioxide (CO₂) concentrations were monitored in a private room of a nursing home in the Kanto Region of Japan, the behaviors of the resident and staff members were recorded, and the relationship between the two was analyzed. Both odor and CO₂ concentrations were higher when the resident was present than when absent, indicating that the resident was one of the main sources of indoor odor and CO₂. In addition, after the resident entered the room, the CO₂ concentration increased and remained stable, whereas the odor concentration tended to vary after the resident entered the room, first increasing and later decreasing. This suggested that the increase or decrease in odor could be used to monitor the behavior of the resident and staff members. The relationship between the slopes of odor and CO₂ in typical behavioral events suggest that if only odor increases and CO₂ does not change, the likelihood of the event in which feces were observed during diaper changes is high. In addition, based on the behavior near the sensor, the rate of CO₂ and odor emissions differed between the elderly resident and the younger staff members, suggesting that the ratio of odor slope to CO₂ slope may be greater in the elderly than in younger people. Furthermore, the repeated number of increases and decreases in odor and CO₂ suggested that multiple events could be distinguished. These results suggest that IAQ can be utilized to estimate the behavior of residents and staff in nursing care facilities for the elderly.