Characteristics of carbonyl compounds in public vehicles of Beijing city: Concentrations, sources, and personal exposures

The characteristics of carbonyl compounds (carbonyls) including concentrations, major sources, and personal exposure were investigated for 29 vehicles including taxi, bus and subway in Beijing. It was found that the taxis (Xiali, TA) and buses (Huanghe, BA) fueled by gasoline with longer service years had the higher indoor carbonyl levels (178±42.7 and 188±31.6 μg m−3) while subways energized by electricity without exhaust and the jingwa buses (BB) driven in the suburb had the lower levels with total concentrations of 98.5±26.3 and 92.1±20.3 μg m−3, respectively. Outdoor carbonyls of taxi cars and buses were nearly at the same level with their total concentrations varying from 80 to 110 μg m−3. The level of outdoor subways carbonyls was equal with the ambient air levels. Exhaust leakage, indoor material emissions, photochemical formation, and infiltration of outdoor air were considered to be the major sources to in-vehicle carbonyls. Personal exposures and cancer risk to formaldehyde and acetaldehyde were calculated for professional bus and taxi drivers, respectively. Taxi drivers had the highest cancer risk with personal exposure to formaldehyde and acetaldehyde of 212 and 243 μg day−1, respectively. The public concern should pay considerable attention to professional drivers’ health.