Impact of PM10 Pollution on Indoor Bacterial Communities: Correlations Between Bacterial Abundance and Physicochemical Parameters in School Environments

Background: Indoor air quality (IAQ) is a critical concern in collective childcare establishments, often subjected to regulatory scrutiny worldwide. Objectives: This study aims to assess bacterial diversity and relative abundances of indoor air in early childhood establishments, evaluate the physicochemical quality, and explore correlations within collected data. Materials and Methods: Bacterial species and their abundances were determined via metataxonomic analyses across three early childhood establishments in Korba, Tunisia, during three seasonal periods. In parallel, monitoring of carbon dioxide, indoor (PM ₁₀ ), and outdoor (PM _10ext ) particulate matter, along with comfort parameters, was conducted. Results: Thirty bacterial species were identified (% of classified reads ≥ 1% at the species level), with prevalence of Staphylococcus saprophyticus , Staphylococcus epidermidis , and Pseudomonas stutzeri . Cumulative bacterial abundance and species count correlated significantly with PM ₁₀ and PM _10ext concentrations. Moreover, Staphylococcus haemolyticus relative abundance correlated significantly with temperature. Hygrothermal discomfort and frequent particulate matter exceedances were observed in the establishments. Conclusions: This study underscores the presence of various bacterial species in indoor air environments and reveals correlations with environmental factors like seasonality, particulate matter levels, temperature, and humidity. These insights enhance our understanding of IAQ dynamics in early childhood establishments, guiding interventions for improved air quality and children's well-being.