Organophosphate flame retardants (OPFRs) in indoor and outdoor air in the Rhine/Main area, Germany: comparison of concentrations and distribution profiles in different microenvironments

The concentrations of 9 organophosphate flame retardants (OPFRs) were determined in 56 indoor and 9 outdoor air samples in the Rhine/Main area in Germany. The indoor samples were collected from seven different indoor microenvironments including private cars, private homes, floor/carpet stores, building material markets, schools, offices, and day care centers, while outdoor samples were simultaneously collected close to the indoor sampling locations. The total OPFR concentrations (Sigma OPFRs) in indoor air ranged from 3.30 to 751.0 ng/m(3) with a median of 40.23 ng/m(3), which was approximately eight times higher than those in outdoor air (median 5.38 ng/m(3)), indicating that sources of OPFRs predominate in the indoor environment. Tris(2-chloroisopropyl) phosphate (TCPP), tris(isobutyl) phosphate (TiBP), and tributyl phosphate (TnBP) were the dominating compounds both in indoor and outdoor air. The median concentration of SOPFRs in private cars (180.3 ng/m(3)) was significantly higher than that in private homes (12.51 ng/m(3)), schools (36.23 ng/m(3)), day care centers (31.80 ng/m(3)), and building material markets (31.17 ng/m(3)) (p < 0.05). Distribution profiles of OPFRs varied among different indoor microenvironments, which are evidenced by dominating indoor air concentrations of non-Cl-OPFRs in day care centers, floor/carpet stores, schools, and of Cl-OPFRs in other indoor microenvironments. Multivariate analyses revealed three distinct groups for OPFRs, i.e., TiBP/TnBP, TEP/TCEP/TDCPP, and TCPP, whose concentrations were closely associated with the distribution profiles and pollution characteristics of materials predominating in different indoor microenvironments.