Contribution of carbonyl compounds to IAQ in schools: a field study

Abstract

With increasing awareness of indoor air pollution and the relation between outdoor and indoor ratios of contaminants, studies have been carried out to determine the concentrations of these pollutants in indoor air especially in schools, restaurants, residential areas and hospitals. Formaldehyde and acetaldehyde are important carbonyl compounds in chemical reactions in the troposphere. However due to their adverse effects on human health and their presence in indoor air, there is a need to monitor and determine their sources in indoor air quality and possible mitigation actions to implement in order to reduce their levels in occupational and living environments. A study was undertaken in a Portuguese school (Escola de Gloria) in Aveiro where indoor and outdoor air carbonyls were measured in order to gain information about child exposure in school environments. Carbonyl compounds were measured using passive samplers over a nine-week period. Active sampling of carbonyls was carried out for three days to determine the time weighted average (TWA) and diurnal variation. Results show the presence of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde and benzaldehyde to be the most common carbonyls found during sampling. High levels of indoor carbon dioxide were found during occupation periods (2671ppm). The concentration of carbonyls obtained during occupation period in the first weeks is higher indoor than outdoor with highest concentrations of acrolein/acetone (2179 μg/m3) found, followed by butyraldehyde (38.51μg/m3), formaldehyde (26.70μg/m3) and acetaldehyde (22.85μg/m3). High I/O ratios were also reported and this could suggest carbonyls being generated from indoors sources