Comfort parameters and particulate matter (PM10 and PM2.5) in school classrooms and outdoor air

Abstract

In January 2012, one kindergarten and eight elementary school classrooms were monitored. The campaign included simultaneous measurements, indoors and outdoors, of comfort parameters, CO, CO<inf>2</inf> and particles. Automatic monitors using a light scattering technique were employed to measure PM<inf>10</inf> continuously. During occupied periods, low volume samplers were used to daily collect PM<inf>2.5</inf> samples, which were subsequently analysed for carbonates, organic carbon (OC), elemental carbon (EC) and water soluble inorganic ions. With regard to comfort, the schools did not meet the recommended levels in many rooms. Indoor-outdoor CO<inf>2</inf> ratios between 3 and 12, and indoor levels much higher than 1000 ppm during the occupied periods, indicate the highly inadequate ventilation in these locations. The results clearly demonstrate that there is a high level of exposure to particulate matter in these schools. The continuous measurements of PM<inf>10</inf> suggest that the physical activity of pupils, which is assumed to be more marked in younger children, contributes to a constant process of resuspension of sedimented particles. In addition, peak PM<inf>10</inf> concentrations coincident with cleaning activities suggest the need to change certain practices to improve cleanliness. Around 40% of the PM<inf>2.5</inf> mass is composed of carbonaceous matter, with 4-5 times higher OC mass fractions than EC. It was observed that both OC and EC were significantly influenced by indoor sources. Water-soluble inorganic ions represented around 10-20% of the PM<inf>2.5</inf> mass measured in classrooms. Excluding calcium, in general the ionic species were present at indoor-outdoor ratios of less than 1, suggesting the major origin in the outdoor air.