The contribution of outdoor particulate matter (PM₁, PM_2.5, PM₁₀) to school indoor environment

Abstract

The contributions of outdoor and indoor sources to the indoor concentrations of particulate matter (PM 1 , PM 2.5 , and PM 10 ) were investigated in a secondary school in Wroclaw, Poland. PM measurements were performed one week per month from December 2009 to October 2010. The sizes of the aerosols generated form indoor sources were in the range of 1–2.5 µm in winter and 2.5–10 µm in summer. It was found that the indoor PM 1 concentrations in the school were mostly due to infiltration, with an infiltration factor of 0.65 in winter and 0.68 in summer. These findings, complemented with single particle analyses (using electron probe X-ray microanalysis) revealed that the finest particles, mostly infiltrated from outdoor air, were dominated by organic carbon, sulphates and that organic carbon particles were associated with fly ash or soil dust. Organic carbon was also associated with larger particles of fly ash or soil dust. As part of mineral dust calcium carbonate, salt particles and aluminosilicates were identified. Thus, it is necessary to evaluate the health risks posed to school children associated with the high exposure to indoor PM containing potentially toxic materials in this and probably other schools.