A territory wide survey on indoor particulate level in Hong Kong

Abstract

Airborne particulates are a major air pollution problem in Hong Kong. Very high outdoor airborne particulate levels have been recorded in the outdoor monitoring stations managed by the Hong Kong Environmental Protection Department (HKEPD). However, information on the concentrations of indoor total suspended particulate (TSP) and particulate matters of aerodynamic size less than 10 μm (PM10) has been scarce. In view of this, a territory-wide survey was conducted from September 1996 to January 1997 to investigate the indoor airborne particulate levels in 50 residential apartments in Hong Kong. In this study, 50 residential premises were selected in 18 districts of Hong Kong covering both public housing and private housing. Two Mini-Vol sampling pumps were located at each site to collect both 24 h TSP and PM10samples in filters which were analyzed by gravimetric method using a precision mass balance. The living habits, ventilation characteristics and other indoor activities were recorded in a survey form. The TSP level varied from 37.5 μg m-3to 227.1 μg m-3and the PM10level varied from 35.1 μg m-3to 161.6 μg m-3, which were much higher than the levels measured in western countries. PM10\TSP percentages varied from 49.7 to 100% (average 85.0%) which were also higher than the data obtained in other overseas studies. A high proportion of respirable content in the indoor environment indicated that there is a significant contribution from indoor activities on the residential premises, e.g. smoking, incense burning and cooking, etc. The findings have been useful for evaluating long term policy regarding environmental protection in the domestic environment.