Outdoor Air Supply Rate Affects Occupant's Perception and Intensity of SBS Symptoms

Abstract

ISEE-135 Objective: The objectives of the study are to obtain the perceptual constructs of the subjective responses through the principal component analysis and to determine the effects of outdoor air supply rate on each perceptual construct or factor. Material and Methods: A blind intervention study was administered on 48 male and 48 female participants (age range: 20–23 years) using a counterbalanced order of exposure to different outdoor air supply rates, ie, 4.5, 9.0, and 18.0 liters per second per person (L/s/p) in a field environmental chamber operating with a total recirculation rate of approximately 6 air changes per hour and media filters. The subjects completed questionnaire on perception of air quality, thermal comfort, indoor parameters, and the intensity of SBS symptoms. Survey results were subjected to principal component analysis and several factors were extracted. The factor scores were subsequently analyzed for the main effects using the nonparametric Friedman test. Results: Ten factors were extracted with a cumulative explained variance of 72%. The most dominant factor (20%) was the neurobehavioral-related symptoms, which included symptoms like depression, difficulty to think, difficulty to concentrate, headache, and dizziness. Neurobehavioral-related symptoms diminished when outdoor air supply rate is increased from 4.5 to 9.0 L/s/p; however, the symptoms increased when outdoor air supply rate is increased from 9.0 to 18.0 L/s/p (P < 0.001). Another relevant factor was perceived odor and irritation, which incorporates the olfaction and chemesthesis responses. The perceived odor and irritation factor decreased with higher outdoor air supply rate (P < 0.0001). This is consistent with improved perception of air quality with elevated outdoor air supply rate (P < 0.02). Conclusions: Neurobehavioral-related symptoms have been identified to respond to exposures to outdoor air supply rate. Higher outdoor air supply rate (up to 9.0 L/s/p) is associated with better perception and lower intensity of symptoms.