Elemental characterization and source identification of size resolved atmospheric particles in French classrooms

Indoor airborne particles were chemically characterized to identify their major sources in 3 elementary schools presenting different site typologies (rural, urban, and industrial) in the North of France. The sampling campaigns were conducted simultaneously indoors and outdoors during 2 weekly periods successively in each school, in presence and absence of pupils. The indoor weekly mean PM10 mass concentrations in presence of pupils varied from 72.7 to 85.3 mu g m(-3), generally exceeding the WHO guidelines. The presence/absence PM10 ratios confirm the PM10 concentrations raise during children's activities. Their presence leads to an increase of elemental concentration (ng m(-3)) but does not influence the elemental distribution in the different particulate fractions. Crustal elements represent an important portion (7-10%) of the indoor PM10 mass, mostly driven by the Ca content (4.4-7.2%) due to the use of chalk. The trace elements (As, Cd, Cu, Pb, Sr, ...) are enriched in the fine fractions (70-100%) compared to the coarse ones. Crustal elements (Al, Ca, Ti, Sr, ...) present higher concentrations in the coarse fractions (40-60%). Elemental ratios and Cluster Analysis confirmed different particulate metal sources from the school surroundings. Among these sources, re-suspension dust, traffic, and marine aerosols were observed in all schools. Mixed anthropogenic sources were identified in urban and industrial sites, and petro-chemistry was only evidenced in the school near the industrial zone. Indoors, these outdoor anthropogenic particles represent the only sources of trace elements evidenced during this study. (C) 2012 Elsevier Ltd. All rights reserved.