Carbon monoxide and volatile organic compounds as indicators of indoor air quality in underground parking facilities

The provision of underground parking facilities (UPFs) has become a necessity particularly in densely populated urban areas and business districts. Indoor air quality (IAQ) in such facilities is of great concern due to vehicle-induced emissions. This paper presents an IAQ assessment at six representative UPFs in Beirut using carbon monoxide and volatile organic compounds as IAQ indicators. For this purpose, concentrations of both pollutants were measured at different time intervals throughout the day. Vehicular emission factors (EFs) were estimated using the EMFAC7F1.1 model. A transient mass balance model was then applied to construct concentration profiles. The ventilation rates required to maintain pollutant concentrations within acceptable standards were estimated under maximum UPF occupancy, and a sensitivity analysis was conducted to evaluate the effect of changes in EMFAC7F1.1 input parameters on EFs and ventilation rates.