Long-term volatile organic compound emission rates in a new electric vehicle: Influence of temperature and vehicle age

Abstract

To investigate the long-term emission characteristics of volatile organic compounds (VOCs) in vehicles, field measurements of the VOC emission rates in a new electric vehicle were conducted for 21 months. During the measuring period, the car was privately used for daily commuting under a natural environment. Detailed in-cabin VOC concentrations, temperature, relative humidity, and air exchange rates were obtained monthly while the car was parked and all windows and doors closed. The influence of in-cabin temperature and car age on the VOC emission rates was explored. For total VOCs, the emission rate was positively associated with the in-cabin temperature and decreased with an increase in vehicle age. For certain VOC species, such as 2-ethyl-1-hexanol, 5-methylundecane, and 3,8-dimethyldecane, the emission rates during the summer were 71–182 times higher than those during the winter. The influence of vehicle age on the VOC species emission rate depended on the compound properties and emission source characteristics. For aromatics, the decay of the emission rate over time was relatively significant; for alkanes and alkenes, the decay of the emission rate over time was relatively minor; and for ketones and aldehydes and esters and alcohols the emission rate was not necessarily negatively associated with vehicle age. These results aid in understanding vehicle cabin air quality and its possible influential factors.