PA20112. Indoor air quality in Portuguese school buildings: Quantification and characterization of microbiota

Abstract Background We are constantly exposed to the risks associated with poor air quality, a risk that is further heightened by the increasing amount of time spent indoors, where pollution levels can be 2 to 5 times higher than those outdoors. This exposure contributes to a greater likelihood of respiratory and allergic diseases, such as allergic rhinitis, conjunctivitis, and asthma, especially among vulnerable groups such as children, the elderly, and individuals with preexisting health conditions. Methods This study focused on school buildings to assess indoor air quality (IAQ) from a microbiological perspective. Eight school buildings were selected for evaluation, and both physical-chemical parameters (CO2, PM10, PM2.5) and microbiological factors (fungi and bacteria) were monitored. Results In terms of physical-chemical parameters, the results were promising. All schools met the legal standards for PM10 and PM2.5, and five out of eight schools complied with CO2 regulations. Comfort levels, as measured by temperature and relative humidity, were rated from high to acceptable. Regarding microbiological parameters, most schools exhibited higher microbial loads indoors compared to outdoors, with a significant increase in microbial presence throughout the day. The isolated aerobic mesophilic bacteria included Sphingomonas paucimobilis, Pseudomonas aeruginosa, Micrococcus luteus, Enterococcus faecalis, Micrococcus lylae, Staphylococcus epidermidis, and Staphylococcus hominis, with the distribution of Gram-negative bacteria ranging from 3% to 26% and Gram-positive bacteria from 74% to 97%. Conclusions Based on the findings, it is clear that the ventilation systems in these buildings (both natural and/or mechanical) need to be reviewed and improved to enhance air exchange rates. Additionally, the installation of high-efficiency air filtration systems (HEPA filters) is strongly recommended to improve overall indoor air quality. Key messages • The air systems in these buildings (both natural and/or mechanical) need to be reviewed and improved to enhance air exchange rates, and if applicable, high-efficiency air filtration systems (HEPA filters) are strongly recommended to improve overall indoor air quality. • Preventive measures such as cleaning spaces and correcting ventilation of spaces must be implemented. Topic Indoor Air quality, Schools, Respiratory pathologies.