Air quality in a school with dampness and mould problems

An air quality monitoring campaign was carried out from the 13th to the 17th of January 2013 in a secondary school of the municipality of Anadia (Portugal) with dampness and mould problems. Continuous measurements of different particulate matter (PM) sizes [PM1, PM2.5, PM4 and PM10 and total suspended particles (TSP)], comfort parameters (temperature and relative humidity), CO, CO2 and total volatile organic compounds were simultaneously carried out in a computer classroom, in the girl's locker/shower room and outdoors. Low-volume samplers were used to collect PM10 samples for subsequent determination of their carbonaceous content. Bacteria and fungi were collected by liquid impinger sampling and by direct scratching of surfaces. Temperature and relative humidity were far outside the comfort ranges in both rooms. Contrary to the locker/shower room, highly inefficient ventilation rates in the computer classroom, with occupancy always higher than 20 students, led to elevated CO2 concentrations (> 2250 mg m(-3)). Much higher particle concentrations were observed in the locker room. Although not allowed, some smoking episodes in this indoor space may have contributed to particle concentrations up to 30 mg m(-3) and to indoor-to-outdoor ratios of 340. If the short smoking episodes are excluded, similar average PM10 levels (< 50 mu g m(-3)) are obtained for both rooms. Around 60 % of the total suspended particles are composed of submicrometric material. The concentrations of total culturable bacteria in the locker room, computer classroom and outdoors were, on average, 1038, 772 and 176 CFU m(-3), respectively. The corresponding fungi concentrations were 285, 542 and 125 CFU m(-3). In most cases, the concentrations of both, culturable bacteria and fungi, were above the legal limits (500 CFU m(-3)). Fungi present in impinger samples and also those collected by direct scratching of surfaces were identified as belonging to the genera Alternaria, Aspergillus, Cladosporium and Penicillium, all of them potentially harmful to human health. A high degree of discomfort, insufficient ventilation in some microenvironments and the presence of allergenic bioaerosols at excessive levels indicate that the adoption of remedial actions is required.