Since children spend a considerable part of the day at school, classroom indoor air quality (IAQ) is a major contributor to their personal exposure. The geographical location of the school, the proximity of outdoor sources (industry or traffic), construction characteristics (including ventilation/heating system), as well as decorations and consumer products, all contribute to classroom IAQ. Considering the potential health impact of a poor IAQ on this susceptible population, suitable measures to assess and mitigate indoor air pollutants (IAP) in school buildings are taken. The last 4 years, several studies on classroom IAQ and source control were organized in Belgium. The use of new, innovative sampling techniques, designed for indoor air monitoring (Lazarov et al. 2013), led to novel insights into classroom environments. In 90 non-mechanically ventilated classrooms, indoor and outdoor levels of traffic-related volatile organic compounds (VOCs) were closely associated. Resuspension by room occupancy caused increased indoor PM2.5 during teaching periods. Indoor CO2 was elevated (reaching 5000ppm) and significantly correlated to indoor VOCs, formaldehyde and PM2.5. Mechanical ventilation in 26 newly built classrooms in low-energy and certified passive buildings (annual energy demand <15kWh/m2) led to higher ventilation rates and air filtration removed outdoor PM2.5 in the air supply. The total air supply per pupil (i.e. summed ventilation rate and air infiltration rate: <3l/s.pp to >15l/s.pp) was inversely associated with indoor toluene, formaldehyde, PM2.5 and CO2. Most abundant phthalates were di-ethylphthalate, di-n-butylphthtalate, and to lesser extent benzylbutylphthtalate. Concentrations up to 8μg/m3 were quantified, resulting from synthetic classroom decorations and products. Following the IAQ assessments, three strategies to optimize/enhance classroom environments were explored (www.vito.be/indoor_air; www.sinphonie.eu): (1) identification and quantification of classroom IAP sources, (2) validation of building materials that enhance IAQ, and (3) improved filter efficiency in the air supply of ventilation systems. The first measure was explored by quantifying emissions of classroom products in test chambers, respecting ISO 16000-9 whilst simulating representative classroom climates. A wooden kindergarten chair emitted 16 different VOCs and aldehydes, including formaldehyde at an emission rate of 4.5μg/h.chair, 6 days after installation. Dry-erase markers emitted 16 VOCs and aldehydes, including benzene, and couch textile emitted tri(2-chloroethyl)phosphate at a rate of 3.5μg/h.m2 60 days after installation. The second measure was explored by exposing a plaster board with IAQ enhancing characteristics to a controlled atmosphere of formaldehyde, toluene, benzene and limonene in a test chamber. The treated board selectively reduced formaldehyde with an efficiency of 79% (loading factor 0.38m2/m3). To explore the third measure, long-term experiments are organised in 4 classrooms to quantify the impact of filter efficiency upgrades on the occurrence of outdoor air pollutants indoors (PMx and soot). The use of innovative indoor sampling methods leads to the identification of critical aspects of school environments. This research illustrates that to create better IAQ at school, risks of IAQ can be tackled by dedicated source control and reduction. B. Lazarov, R. Swinnen, M. Spruyt, E. Goelen, M. Stranger, G. Desmet, E. Wauters. Optimisation steps of an innovative air sampling method for semi-volatile organic compounds. Atmospheric Environment 79(2013); 780-786.


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