Preventing Sick Building Syndrome in Student Houses: A Cross‐Sectional Analysis of Indoor Air Quality–Related Symptoms

Introduction. Indoor air quality (IAQ) is a key determinant of health in enclosed environments, and it plays a relevant role in the onset of symptoms associated with sick building syndrome (SBS). In particular, student houses warrant particular attention, given that their environmental conditions are strictly controlled by the facility management through dedicated operational activities. Starting from an analysis of two facilities in Milan with continuous monitoring of air temperature, relative humidity, air pressure, CO2 concentration, particulate matters (PM2.5 and PM10), and tVOC concentration, a cross-sectional observational study was developed on environmental parameters and users′ symptoms. This study is aimed at evaluating the prevalence of SBS-compatible symptoms among student residents and at analyzing their potential associations with monitored indoor environmental parameters. Methodology. The study conducted IAQ monitoring activities and surveys on users′ perception in seven fieldwork periods between May 2024 and June 2025. About 30 low-cost sensors were deployed in each period in many rooms with different floor levels and orientations, as well as qualitative questionnaires that collected users′ perceptions of IAQ-related symptoms, behaviors, occupancy, window openings, and so forth to support data interpretation. Results and Discussion. The analysis permitted to investigate 51 rooms for each monitoring period and to obtain in total 74 questionnaires, of which the paper examines 27 specific environmental units, that showed a stronger concordance between symptoms and IAQ anomalies. The measurements revealed temperatures frequently above comfort thresholds, relative humidity often below the comfort range, and PM2.5 concentrations consistently exceeding reference values, while CO₂ levels generally showed acceptable limits. Meanwhile, the most frequently reported symptoms included sneezing, mucosal dryness or sore throat, headache, cough, and nasal congestion. In general, specific environmental deviations corresponded to the types of symptoms reported by occupants. Conclusions. The findings emphasize an association between altered IAQ and SBS-compatible symptoms and point to the value of combining environmental measurements with occupant perception data, though the observational design of the study does not allow for causal conclusions. Consequently, continuous monitoring supports proactive IAQ management, and the findings highlight the need for behavioral guidance to maintain healthy buildings.