Air Quality in Urban Mobility Hubs: An Analysis of Particulate Matter in Underground Transport Spaces

Enclosed transport environments are becoming an integral part of compact urban structures; however, their air quality is monitored less systematically than that of the outdoor urban environment. This study evaluates particulate matter concentrations (PM1, PM2.5, PM10) in two urban microenvironments in Banská Bystrica (Slovakia): an underground parking garage (representing private urban mobility) and an underground bus station (representing public transport). Continuous measurements using an enviDUST monitoring device were analysed in relation to occupancy rates and transport intensity. The results showed a dominance of the PM10 fraction in both environments, suggesting the importance of non-exhaust sources and dust resuspension in enclosed urban transport spaces. In the parking facility, the immediate relationship between occupancy and PM concentrations was weak; however, a time lag effect was observed, indicating particle accumulation. The bus station exhibited higher average concentrations (PM1: 8.67; PM2.5: 14.12; PM10: 34.12 µg/m3), while peak levels during nighttime highlighted the critical role of air stagnation and ventilation regimes. The study emphasizes the need to perceive such transport nodes as semi-public urban spaces requiring the integration of intelligent air quality management within sustainable urban development.