Chemical characterization of household dust in two major cities: COlombo, The Capital And Kandy, The Hill Capital, Sri Lanka

Household dust is an important environmental medium that affects human health. In this study, the levels of several heavy metals and other major elements in household dust in two cities of Sri Lanka were analyzed for the first time to interpret the possible sources and the factors controlling the chemical characteristics of household dust. Fifty four (54) dust samples from Colombo, the capital of Sri Lanka, located in the west coast and from the city of Kandy, located in central highlands were collected. Acid digested samples were analyzed by Atomic Absorption Spectrophotometry (AAS). The average concentrations of Pb, Cr, Mn, Cu, and Zn were found to be 2.3, 0.8, 191, 2, and 18.1 ppm respectively, in the household dust samples of Colombo city. The average concentrations of the above elements in the household dust of Kandy urban area were 3.5, 0.7, 347, 94.2 and 738 ppm respectively. Fe, Na and Ca concentrations in both areas show higher values; 3.2, 0.3 and 0.05 wt. % respectively, in Colombo and 3.2, 2.8 and 2.6 wt. % respectively, in Kandy. The levels of concentrations of measured elements of Colombo samples are relatively low compared to those found in Kandy though the Colombo city is heavily urbanized. The influence of wind pattern, high humidity and flat land area may have caused the low concentrations of measured metals in Colombo area while wind circulation and comparatively low humidity in Kandy which also is a valley area, may have accumulated those elements in dust. The present study reveals that urbanization and related anthropogenic activities are not only the main factors controlling the contamination of urban dust, but also natural conditions such as morphology, overburden soil cover and hydro meteoric conditions are also important factors contributing to the heavy metal pollution in dust samples.