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

摘要

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 PM_(10) mass concentrations in presence of pupils varied from 72.7 to 85.3 μg m~(-3), generally exceeding the WHO guidelines. The presence/absence PM_(10) ratios confirm the PM_(10) concentrations raise during children's activities. Their presence leads to an increase of elemental concentration (ngm~(-3)) but does not influence the elemental distribution in the different paniculate fractions. Crustal elements represent an important portion (7-10%) of the indoor PM_(10) mass, mostly driven by the Ca content (4.4-7.2%) due to the use of chalk. The trace elements (As, Cd, Cu, Pb, Sb,...) 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.