Concentrations of volatile organic compounds in vehicular cabin air – Implications to commuter exposure

Abstract

In this study, 117 volatile organic compounds (VOCs) were identified and quantified inside passenger cars and buses operating city and intercity routes. The paper presents data for 90 compounds with frequency of detection equal or greater than 50% that belong to various chemical classes. Total VOC concentration (TVOCs) was dominated by alkanes followed by organic acids, alkenes, aromatic hydrocarbons, ketones, aldehydes, sulfides, amines, and phenols, mercaptans, thiophenes. VOCs concentrations were compared between different vehicle types (passenger cars - city buses - intercity buses), fuel type (gasoline - diesel - liquefied petroleum gas (LPG)), and ventilation type (air condition - air recirculation). TVOCs, alkanes, organic acids and sulfides followed the order: diesel cars > LPG cars > gasoline cars. On the contrary, for mercaptans, aromatics, aldehydes, ketones, and phenols the order was: LPG cars > diesel cars > gasoline cars. Excepting ketones that were found to be higher in LPG cars with air recirculation mode, most compounds were higher with exterior air ventilation in both, gasoline cars and diesel buses. Odor pollution, expressed by the odor activity value (OAV) of VOCs, was highest in LPG cars and minimum in gasoline cars. In all vehicle types, mercaptans and aldehydes were the major contributors to odor pollution of the cabin air with lower contributions from organic acids. The total Hazard Quotient (THQ) was less than 1 for bus and car drivers and passengers indicating that adverse health effects are not likely to occur. Cancer risk from the three VOCs following the order naphthalene > benzene > ethylbenzene. For the three VOCs the total carcinogenic risk was within the safe range. The results of this study expand our knowledge of in-vehicle air quality under real commuting conditions and give an insight into the commuters’ exposure levels during their normal travel journey.