D3.471 - Invisible Ventilation Gaps: Continuous Low-Cost Indoor Air Quality Monitoring in a Northern Portuguese Hospital

Indoor air quality (IAQ) is a critical component of hospital environmental safety, influencing thermal comfort, perceived air freshness, and healthcare workers’ conditions, while being especially relevant for vulnerable patients. Hospital departments are dynamic microenvironments where ventilation effectiveness, occupancy, and routine activities vary across the day, potentially affecting gaseous indicators and particulate loads. To address this need, continuous IAQ monitoring was conducted in a real hospital department using a portable low-cost platform.

A portable low-cost monitoring system was deployed in a hospital department in Northern Portugal to record CO₂, PM2.5, PM10, temperature, and relative humidity at 1-minute intervals. The platform integrates non-dispersive infrared (NDIR) sensing for CO₂ and laser-scattering sensing for particulate matter, alongside temperature/relative humidity sensing, in line with Portuguese IAQ monitoring priorities. It was analyzed 3,463 data points collected across 8 monitoring days (February 2026). Overall results are reported as mean ± standard deviation (SD). Diurnal behavior was characterized by (i) computing hourly means within each day and (ii) averaging matching clock-hours across days. 

Overall conditions were CO₂ 901±127ppm, PM2.5 2.10±1.15µg/m³, PM10 8.49±5.56µg/m³, temperature 26.96±1.72°C, and relative humidity 44.46±6.97%. The hour-of-day analysis (Figure 1) was derived from the available monitoring window (07:00–15:00). Within this window, the diurnal profile identified 12:00 as the highest mean hour for CO₂ (982 ppm). PM2.5 reached its highest hourly mean at 14:00 (2.21 µg/m³), while PM10 peaked at 12:00 (8.58 µg/m³). Temperature peaked at 13:00 (27.65 °C), and relative humidity was lowest at 14:00 (41.97%). Particulate matter results should be interpreted cautiously because the monitoring period coincided with intense rainfall, which can suppress airborne particle concentrations through wet scavenging.

Continuous low-cost monitoring enabled time-resolved characterization of IAQ indicators and highlighted a consistent midday CO₂ elevation. Compared with WHO guideline-based screening values, CO₂ and PM10 exceeded selected thresholds at least once on most monitored days. These observations support follow-up campaigns under different operational and meteorological conditions and a context-specific review of ventilation and occupancy patterns.