Preliminary results on indoor environmental quality in day care centers located in Lisbon

Cano, M.; Azevedo, S.; Aguiar, F.; Almeida, G.; Brás, C.; Pinhal, H.; Nogueira, A.; Proença, M.C.

http://hdl.handle.net/10400.18/830

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The growing concern about indoor air quality results from the knowledge that exposure to indoor air pollutants may be higher than the exposure to outdoor air pollutants and from the evidence that in most developed countries day care centers are places where children spend most of their time. How environmental factors affect children respiratory health is still controversial and unclear. This paper describes the results from field measurements of physical parameters, chemical and biological indoor contaminants, to investigate indoor environmental quality, in 70 classrooms of 10 Children Day Care Centers (CDCC), located in Lisbon. Objective The aim of this study is to gather information on indoor environment of CDCC in order to correlate it with both ventilation and children’s health. Material and Methods Chemical contaminants (carbon dioxide, carbon monoxide, formaldehyde, total volatile organic compounds and PM10), biological contaminants (bacteria, fungi and house-dust mites) and thermal comfort parameters were monitored. Formaldehyde was analyzed according to NIOSH 3500 method using a visible absorption spectrometry with air samples taken on impingers by active sampling. Total volatile organic compounds were analyzed by gas chromatography according to the ISO 16000, part 6, with air samples taken on Tenax TA sorbent by active sampling. Carbon monoxide and carbon dioxide measurements were made using a Photoacoustic Multi- Gas Monitor INNOVA. Samples of viable microorganisms were collected using a MAS-100 sampler with Malt Extract Agar plates, Trypticase Soy Agar and MacConkey agar as collecting media for fungi, total bacteria and gram-negative bacteria. Dust samples were collected on filters using a vacuum cleaner with a DustreamTM collector and determined using an ELISA test to quantify mite antigens. PM10 were collected using PTFE filters on Personal Environmental Monitors attached to personal pumps and the filters were analyzed gravimetrically for particle mass. Thermal comfort was evaluated according to the ISO 7730 International Standard using a 1213 Bruel & Kjaer analyzer. Results The reported preliminary results only represent a small part of a larger study under development in 20 CDCC located on Lisbon and Porto. The mean CO2 concentration indoors exceeded the recommended level of 1800 mg/m3 in 54% of the 70 studied rooms, with a maximum concentration of 5630 mg/m3 and an outdoor average of 839 mg/m3. The majority of the studied rooms had suspended particulate matter, TVOC’s and formaldehyde concentrations under the recommended limits. In 51% of the rooms the bacterial concentrations exceed 500 ufc/m3 (recommended limit), being also observed predominance gram-positive bacteria. In 50% of the studied rooms fungal concentrations were above 500 ufc/m3, however the mean outdoor concentration was 560 ufc/m3. Conclusion The preliminary results provide evidence that ventilation is insufficient, resulting in the accumulation of human source contaminants, such as bacteria and CO2. Taking into consideration that the results correspond to the Spring period, when occupants maintain windows and doors open, we expect worse results in the Winter period.