PRINCIPAL COMPONENT ANALYSIS ON SUBJECTIVE RESPONSES FOR HEALTHY AND SENSITIVE PEOPLE IN THE TROPICS UNDER TWO DIFFERENT OUTDOOR AIR SUPPLY RATES

Abstract

In today’s context, a large proportion of office workers in the tropics spend most of their time in air-conditioned buildings. With prolonged exposure to the indoor environment, concern for the impact of indoor air quality on the occupants’ health and comfort arises. Furthermore, it was noted that few studies have been done on the effects of indoor air quality on asthmatic subjects. Therefore, the effects of outdoor air supply rate on subjective responses were investigated for both healthy and asthmatic people. It was hypothesised that outdoor air supply rates significantly affect the subjective responses of asthmatic and healthy people, and that the subjective responses of asthmatics differ from those of healthy individuals. The experiment was conducted in a field environmental chamber located in the tropics and two outdoor air supply rates were tested – 6 L/s/p and 13 L/s/p. Principal component analysis was carried out to reduce the dimensionality of the subjective responses obtained from survey questionnaires. Subsequently, non-parametric analysis was done on subjective factors to investigate the effects of outdoor air supply rate and the differences in perceptions between healthy and asthmatic subjects. It was found that higher outdoor air supply rate improved several SBS symptoms for both groups of subjects, except for neurobehavioral-related symptoms where the asthmatic group expressed worsening of these symptoms. Asthmatic subjects perceived more odour and experienced more irritations and neurotoxic effects in contrast to healthy subjects. This suggests that asthmatic people are more sensitive than healthy people, and also both groups have differing IAQ perception.