Heavy metals in indoor settled dusts in Toronto, Canada

Total concentrations of eight potentially toxic heavy metals (Ba, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) in indoor settled dusts from houses, offices, classrooms, and laboratories in the Greater Toronto Area (GTA), Canada were determined, and the results were compared. The concentrations of these metals were determined through microwave digestion followed by quantification using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The results indicated that the values of heavy metal concentrations in indoor settled dust vary with different indoor environments, with the highest levels found in laboratory dusts (Ba: 152 mg kg^-1; Cd: 12 mg kg^-1; Cr: 87 mg kg^-1; Cu: 411 mg kg^-1; Mn: 216 mg kg^-1; Ni: 146 mg kg^-1; Pb: 86 mg kg^-1; Zn: 3571 mg kg^-1), while the metal concentrations (except for Mn and Zn) in households, offices, and classroom dusts were lower (0.5-0.67 × the laboratory dust values), and comparable to one another. While all the metals studied show an enrichment factor (EF) greater than one, the EF for Cd, Cu, Pb, and Zn ranged from 15 to 554, indicating significant anthropogenic internal sources of these metals.