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 and there were relatively high Pb levels near motorways. Mean concentrations 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 concentrations 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), respectively. The main source of these heavy metals, in both outdoor and indoor dusts, was from automobile emissions. The relationship between outdoor and indoor dusts was investigated. In view of the high levels of some of these toxic metals, these can be considered a significant hand-to-mouth source of exposure, especially for children.