Trace elements in fine particulate matter within a community in western Riverside County, CA: focus on residential sites and a local high school

Measurements of mass concentrations of 35 trace elements (TEs) and of total fine particulate matter (PM2.5) were conducted at 20 residences and six high school rooms in Mira Loma, California, from September 2001 to January 2002. Sulfur (S) and silicon (Si) were the most abundant TEs measured (excluding a residence with heavy smokers). On average, total TE concentrations were lower indoors relative to outdoors; the proportion of TEs in total PM2.5 was also lower indoors relative to outdoors. Among indoor sites, TE concentrations were found to be lower inside the schoolrooms relative to inside the residences. Environmental tobacco smoke (ETS) was found to contribute significantly to elevated levels of total TE inside residences; however, concentrations of carcinogenic TEs were not significantly different between residences with and without smokers. Potassium (K) and chlorine (Cl) were the most abundant species in a residence with frequent indoor smokers. Combustion-related elements were more enriched inside the residences relative to crustal elements.