Home sweet home? A case study of household dust contamination in Hong Kong

It is well recognized that many heavy metals have chronic effects on humans and as such, they are potential environmental health hazards, particularly to young children (see, for example, Body P, Inglis G, Dolan P, Mulcahy D. Environmental lead: a review. Grit Rev Environ Control 1991;20:299-310). C onsiderable attention has been paid to the study of metal pollution in city air, roadside dusts and soils. However, there is a lack of concern of the presence of trace metals in house dust in the populous city of Hong Kong, w here it has traditionally been assumed that such pollutants are rapidly dis persed by ocean breezes. This research aims at quantifying the concentratio ns of heavy metals within the home environment in Hong Kong and their relat ionships with environmental factors. The results of this study seem to sugg est that traffic and the age of the building and neighborhood are more impo rtant factors than the types of industry and socioeconomic status in affect ing household dust contamination. The metal burdens in Kwung Tong, an old a rea with heavy traffic, are significantly higher than other districts. When a Kruskal-Wallis one-way analysis of variance was performed on the ranked metal concentrations in different housing districts, the Chi-square values are all significant at a probability level of < 0.001. This might be attrib utable to the fact that there is no highly contaminating industries (such a s metal smelters, battery plants and petrochemicals) in Hong Kong. The dust metals may travel from the roads, through the windows and balconies, into the houses, as those homes that do not have their windows opened often had a lower lever of contaminants in their house dust (median Cd = 3.6 mu g/g; median Cu = 313.2 mu g/g; median Pb = 144.6 mu g/g; median Mn = 211.6 mu g/ g; and median Zn = 1333.7 mu g/g). Moreover, those occupants who sweep thei r floors or dust their furniture on daily bases, or use vacuum cleaners, ha d a lower level of metals inside their houses. Another finding of interest is that the color of the wall paint used in the house may be another factor influencing the contamination levels. (C) 2000 Elsevier Science B.V. All r ights reserved.