林 立也

kkPeople's living environments and lifestyles have drastically changed with the times. It is necessary to reassess risk factors associated with changes in social conditions to prevent sick building syndrome (SBS). This study aimed to determine the association between the onset of SBS and participant characteristics, social and residential environments, and lifestyle. An online nationwide questionnaire survey involving 4996 participants was conducted. The risk factors for SBS were examined using logistic regression analyses. The main risk factors for SBS were female sex (odds ratio [OR] = 1.20, confidence interval [CI] = 1.01-1.42) and young age (OR = 2.42, CI = 1.55-3.78). Other risk factors included having a medical history of allergies and mental illness (OR = 1.75, CI = 1.34-2.29), special housing specifications for the indoor environment (OR = 0.77, CI = 0.63-0.95), smoking indoors (OR = 1.25, CI = 1.00-1.55), and others. Women, young individuals, and those with a history of diseases, such as allergies and mental illness, had an increased risk of SBS, indicating that such individuals need to pay attention to chemical exposure. The study results indicate the possibility of preventing SBS by the careful selection of indoor environments and lifestyle.

In this paper, the flow field in human's respiration area was examined through the PIV (Particle Image Velocimetry) experiment using an experimental thermal manikin and CFD analysis, with the assumption of steady inhalation and unsteady breath. In the CFD analysis, the variation of the air-velocity distribution, and the influence of the exhaustion on the inhalation were examined in detail. Moreover, to account for the influence of the three-dimensional forms of the human body, a model that replicated the actual forms of a real human body was used in the simulation. It indicates that each breathing cycle can be taken as an independent process and the real breathing can be assumed as steady inhalation in CFD analysis on inhaled air region. Moreover, the CFD method using a human body with a complex shape indicates to be effective in the study on the flow field in human's respiration area.

The purpose of the paper is to analyze passive-smoking in a room with 3-dimensional CFD analysis. We examine how much the breathing/inhalation air region is polluted by the smoke blown from a smoker's mouth or by the smoke arising from a lit cigarette. We evaluate the degree of pollution around the nose and mouth considering the indices of ventilation effectiveness. Displacement ventilation and mixing ventilation are tested as a ventilation system of the room. In the case of displacement ventilation, we examine two cases with the different speed of exhalation velocity. We observe that the thermal plume caused by the metabolic heat generation of the smoking person effectively transports both the cigarette smoke and blown smoke from the mouth upward and thereby the opposite-side person (passive smoking person) is not affected so much by the smoke. High-exposure case occurs only for the case with the high speed exhalation velocity and with the close distance between smoking and passive smoking person. On the other hand, in the case of mixing ventilation, the smoke tends to diffuse uniformly within the room regardless of the distance of the two persons.