Assessment of the pro-inflammatory potential of inhalable atmospheric particles in school environments

Atmospheric pollution is a major anthropogenic issue that compromises the well-being of populations and ecosystems, as well as the air quality of indoor environments. Recent studies have drawn attention to the harmful effects of exposure to excessive levels of fine particulate matter (PM_2.5), mostly caused by exacerbated and systematic inflammatory and oxidative responses. However, the limited characterization of the water-soluble organic carbon (WSOC) fraction of indoor PM_2.5 and the lack of studies specifically focused on indoor environments hinder our ability to understand the biological consequences of chronic exposure to high indoor PM_2.5 levels. The present study aims to address part of these knowledge gaps by collecting PM_2.5 samples in an indoor school environment in Aveiro during the winter and spring seasons, followed by chemical characterization of their water-soluble fraction in terms of WSOC and ion content, fluorescence and UV-Vis absorption properties, and NMR structural features. The sampling campaigns found indoor concentrations of PM_2.5 consistently higher than the WHO’s recommended limit (5 µg m^-3) and, for most of the winter period, also exceeded the levels established in the national and EU legislations. The optical properties of the aqueous extracts showed that the indoor school environment was strongly influenced by both anthropogenic and biogenic emission sources. Additionally, the pro-inflammatory and oxidative potential of the water-soluble fraction will be assessed in pulmonary epithelial and macrophage cell lines, in order to better understand the role of this fraction on the respiratory effects caused by exposure to elevated indoor PM_2.5 levels.