RESUMEN
Cigarette smoke is the main source of indoor chemical and toxic elements. Cadmium (Cd), Thallium (Tl), Lead (Pb) and Antimony (Sb) are important contributors to smoke-related health risks. Data on the association between Rare Earth Elements (REE) Cerium (Ce) and Lanthanum (La) and domestic smoking are scanty. To evaluate the relationship between cigarette smoke, indoor levels of PM2.5 and heavy metals, 73 children were investigated by parental questionnaire and skin prick tests. The houses of residence of 41 "cases" and 32 "controls" (children with and without respiratory symptoms, respectively) were evaluated by 48-h PM2.5 indoor/outdoor monitoring. PM2.5 mass concentration was determined by gravimetry; the extracted and mineralized fractions of elements (As, Cd, Ce, La, Mn, Pb, Sb, Sr, Tl) were evaluated by ICP-MS. PM2.5 and Ce, La, Cd, and Tl indoor concentrations were higher in smoker dwellings. When corrected for confounding factors, PM2.5, Ce, La, Cd, and Tl were associated with more likely presence of respiratory symptoms in adolescents. We found that: i) indoor smoking is associated with increased levels of PM2.5, Ce, La, Cd, and Tl and ii) the latter with increased presence of respiratory symptoms in children.