a multi-pollutant seasonal assessment

Funding Information: Against this backdrop, several studies have demonstrated a direct relationship between air quality and students' academic performance. For example, a one-year cohort study by Basaga\u00F1a et al. [6] with a sample of 2,618 students from 39 schools in Barcelona, Spain, found that, after characterising pollution sources in these educational establishments, traffic was the only source of fine particulate matter associated with decreased cognitive development. The researchers observed that higher levels of PM2.5 exposure in classrooms correlated with significantly reduced working memory in 8.5-year-old children. Furthermore, in their literature review, Roche et al. [7] concluded that scientific evidence on air pollution highlights its negative on children's cognitive and respiratory health, as well as their academic performance, and increases their susceptibility to diseases in adulthood. It is precisely because of this concern that the European Union (EU) has actively promoted and supported programmes aimed at improving air quality in schools [8,9]. However, despite these efforts, significant challenges remain, especially at the legislative level, where there are still no specific programmes dedicated solely to improving air quality in schools. In contrast, since 2017, the New Zealand government has taken a proactive approach by implementing the Design of Quality Learning Spaces (DQLS) guidelines, aimed at ensuring that the design and construction of school buildings create environments that support effective teaching and learning. In its latest 2022 update [10], the document expanded its focus to include parameters such as temperature, relative humidity, CO2, ventilation rate, and window-to-wall ratio. Although schools are not required to have their own indoor air monitoring devices, the guidelines do establish mandatory requirements for specific parameters during school hours, tailored to the type of room (such as laboratories, gymnasiums, classrooms, libraries, etc.).In addition to cleaning products, other factors can affect carbonyl concentrations. Peng et al. [45] analysed the air quality in an older office and classroom building with complaints about odours and pollutants. They investigated VOCs and carbonyls on three floors. The results showed that the mean indoor/outdoor (I/O) ratios of carbonyls, such as formaldehyde, acetaldehyde, acetone, propionaldehyde, butyraldehyde, benzaldehyde, isovaleraldehyde, valeraldehyde and hexaldehyde exceeded unity, indicating indoor sources for these compounds. When comparing concentrations on weekdays and weekends, they found no significant differences, suggesting that the sources come from the building materials and not the occupants. This finding is supported by a study inParis [46], where factors such as recent wall and floor coverings, environmental tobacco smoke, CO2 levels and temperature were identified as contributing to concentrations of formaldehyde, acetaldehyde, propionaldehyde and benzaldehyde. By comparing these results with those of the present study, it is concluded that carbonyls in classrooms also come from internal sources, as demonstrated by the exclusive presence of certain concentrations detected only indoors (Fig. 6). Some studies have indicated that carbonyl concentration depend on T and RH. Chang et al. [47] reported a strong positive correlation between formaldehyde levels and both indoor T and RH. Similarly, Zhang et al. [48] observed that formaldehyde concentrations were correlated with indoor T, RH, and the time since the property was last decorated.The authors would especially like to thank the school principal and teachers, who have willingly participated in this study. The authors acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) to CESAM (UID Centro de Estudos do Ambiente e do Mar UID/50006 + LA/P/0094/2020, doi.org/10.54499/LA/P/0094/2020), through national funds, and to the PhD fellows I. Charres (DOI: 10.54499/2022.12142.BD), L. Furst (DOI:10.54499/2020.08461.BD), and M. Soares (2023.04826.BD). FCT is also acknowledged for the research contract under Scientific Employment Stimulus to Estela D. Vicente (DOI:10.54499/2022.00399.CEECIND/CP1720/CT0012). This work was performed within the project: Source drivers of (eco)TOxicity of airborne Particles in school environments in Estarreja: Strategies for minimising the risks (STOP) \u2013 funded by the LabEx-DRIIHM-OHM programme (CNRS \u2013 INEE, France). H&TRC authors gratefully acknowledge the FCT/MCTES national support through the UIDB/05608/2020 (https://doi.org/10.54499/UIDB/05608/2020) and UIDP/05608/2020 (https://doi.org/10.54499/UIDP/05608/2020). Funding Information: The authors would especially like to thank the school principal and teachers, who have willingly participated in this study. The authors acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) to CESAM (UID Centro de Estudos do Ambiente e do Mar UID/50006 + LA/P/0094/2020, doi.org/10.54499/LA/P/0094/2020), through national funds, and to the PhD fellows I. Charres (DOI: 10.54499/2022.12142.BD), L. Furst (DOI:10.54499/2020.08461.BD), and M. Soares (2023.04826.BD). FCT is also acknowledged for the research contract under Scientific Employment Stimulus to Estela D. Vicente (DOI:10.54499/2022.00399.CEECIND/CP1720/CT0012). This work was performed within the project: Source drivers of (eco)TOxicity of airborne Particles in school environments in Estarreja: Strategies for minimising the risks (STOP) \u2013 funded by the LabEx-DRIIHM-OHM programme ( CNRS \u2013 INEE , France). H& TRC authors gratefully acknowledge the FCT / MCTES national support through the UIDB/05608/2020 ( https://doi.org/10.54499/UIDB/05608/2020 ) and UIDP/05608/2020 ( https://doi.org/10.54499/UIDP/05608/2020 ). Publisher Copyright: © 2025 The Authors