Exposure to respirable particles and TVOC in underground parking garages under different types of ventilation and their associated health effects

Vehicle-induced pollutants in closed underground parking garages represent a major environmental issue influencing human health. In this study, the exposure to particulate matter (PM₁₀, PM₄, and PM_2.5) and health risk assessments were analyzed using the lifetime average daily doses (LADDs) and cancer risks for selected volatile organic compounds (VOCs). Ventilation types and traffic volumes were used as parameters to characterize variations of the PM and total volatile organic compounds (TVOCs). In the investigated underground parking garage, the mass concentrations of PM₁₀, PM₄, and PM_2.5 were 107.2–213.6, 78.4–138.3, and 56.2–102.4 μg m⁻³, respectively, and TVOC concentrations ranged from 523.0 to 1064.0 μg m⁻³ during the summer and winter seasons. Hourly PM_2.5 concentrations during the daytime were higher than those measured at night, while no significant difference was observed between day and night for TVOC concentrations. The linear regressions for TVOC and traffic volume show that TVOC concentrations increased with increasing traffic. Among the I/O ratios for PM investigated during summer and winter, the only statistically significant difference was observed between natural and mechanical ventilation in parking garages. For all generated PMs, 72.2–80.1% of the aerosol deposition occurred in the head airways, while 4.8–5.1% of the total was deposited in the alveola and 2.5% in the tracheobronchial regions. The data presented herein suggest that, depending on ventilation types, the highest respirable particles generate in underground parking garage and deposit in all respiratory regions. The estimated cancer risks for car park users and occupational staff were determined, and possible and probable risks were measured.