STUDY OF HORIZONTAL AND VERTICAL DISTRIBUTION PROFILES OF TRAFFIC-GENERATED POLLUTANTS IN NATURALLY-VENTILATED H-SHAPED RESIDENTIAL BUILDNG [BUILDING] LOCATED IN CLOSE PROXIMITY TO EXPRESSWAY IN SINGAPORE

Abstract

Traffic-generated pollutants are one of the major sources that contribute to the urban air pollution. Human exposure to particulate matter is critical since fine particles get deposited deep into the respiratory tract and can lead to various respiratory diseases and premature deaths. The aim of this study is to assess the horizontal and vertical distribution profile of traffic-generated pollutants of a residential building in close proximity to an expressway. A comprehensive field study was carried out at a naturally-ventilated residential Hshaped point-block building located near to the Ayer Rajah Expressway (AYE) in Singapore. These two types of traffic-generated pollutants, NO and PM 2 2.5, are covered in this study. Measurements of NO concentration, PM 2 2.5 count levels, wind speed, wind direction, temperature and RH were performed with different instruments located at the upper, mid and lower regions of the building. NO2 was used as a surrogate indicator of PM2.5 and show a fairly good correlation between them in this study. Indoor-outdoor (I/O) ratio was used to ascertain the migration of NO and PM 2 2.5. The maximum NO2 concentration occurred at the mid region of the building instead of the normal negative relationship with height. This could be due to the presence of tree canopy alongside of expressway that helps to absorb or deflect the low level air towards the mid region of the building. These findings have significant implications on the planning of urban areas that has a dense population like Singapore and for management of indoor air quality in naturallyventilated buildings located in close proximity of major roads and expressways.