METAL LEVELS IN INDOOR AND OUTDOOR DUST IN RIYADH, SAUDI-ARABIA

Concentrations of Cd, Cr, Cu, Li, Ni, Pb, and Zn of outdoor and indoor dusts in Riyadh, Saudi Arabia, have been investigated in relation to particle sizes 0.04-0.08 mm using Atomic Absorption Spectroscopy (AAS) . Although the results showed relatively low contamination in general, the old industrial area had appreciably high levels of toxic metals a nd there were relatively high Pb levels near motorways. Mean concentra tions of outdoor dusts for Cd, Cr, Cu, Li, Ni, Pb, and Zn were 2.5 +/- 0.3, 35.1 +/- 2.7, 93.9 +/- 41.9, 4.6 +/- 0.3, 43.9 +/- 5.6, 1762 +/- 593, and 443 +/- 223 mu g.g(-1), respectively, and mean concentration s of indoor dusts were 2.0 +/- 1.1, 69.2 +/- 16.5, 271 +/- 140, 6.2 +/ - 0.5, 52.9 +/- 17.7, 639 +/- 279, and 547 +/- 197 mu g.g(-1), respect ively. The main source of these heavy metals, in both outdoor and indo or dusts, was from automobile emissions. The relationship between outd oor and indoor dusts was investigated. In view of the high levels of s ome of these toxic metals, these can be considered a significant hand- to-mouth source of exposure, especially for children.