INDOOR AIR QUALITY AND SICK BUILDING SYNDROME–RELATED SYMPTOMS IN STUDENT HOUSING: A CROSS-SECTIONAL ANALYSIS

INTRODUCTION Indoor air quality (IAQ) is a key determinant of health in enclosed environments and plays a relevant role in the development of symptoms associated with Sick Building Syndrome (SBS). Student housing deserves particular attention, as environmental conditions are largely determined by centralized facility management and standardized operational practices. OBJECTIVE This study is based on the analysis of two student housing facilities in Milan, where continuous monitoring of physical parameters, CO₂, particulate matter, and total volatile organic compounds (TVOCs) was conducted. Building on this monitoring framework, a cross-sectional observational study was developed to explore the relationship between IAQ parameters and occupants’ reported symptoms. METHODS IAQ monitoring activities and occupant perception surveys were carried out over seven fieldwork periods between May 2024 and June 2025. Approximately 30 low-cost sensors were deployed during each period in rooms with different floor levels and orientations. In parallel, structured questionnaires were administered to collect information on IAQ-related symptoms, occupants’ behaviours, occupancy patterns, and window-opening habits, supporting the interpretation of the measured data. RESULTS The analysis covered 51 rooms per monitoring period and yielded a total of 74 completed questionnaires. Among these, the paper focuses on 27 environmental units that showed a stronger concordance between reported symptoms and IAQ anomalies. The measurements revealed indoor temperatures frequently exceeding comfort thresholds, relative humidity often below the recommended comfort range, and PM₂.₅ concentrations consistently above reference values, while CO₂ levels generally remained within acceptable limits. The most frequently reported symptoms included sneezing, mucosal dryness or sore throat, headache, cough, and nasal congestion. Overall, specific environmental deviations were found to correspond to the types of symptoms reported by occupants. CONCLUSIONS The findings confirm an association between altered IAQ conditions and SBS-compatible symptoms, highlighting the importance of integrating instrumental measurements with occupants’ perceptions. Continuous environmental monitoring emerges as a strategic tool for understanding indoor conditions, while the study also emphasizes the need to promote behavioural best practices to ensure healthy student housing environments