Volatile organic compounds (VOCs) emission profiles of diesel vehicles based on cluster analysis

Abstract

Diesel vehicle VOC emissions are increasingly recognized as key contributors to ambient ozone (O₃) and secondary organic aerosol (SOA) formation. Although recent studies have focused on total volatile organic compound (VOC) quantities, detailed chemical profiles remain poorly characterized due to regional, fuel-type, and vehicle-technology heterogeneity. This study aims to address these uncertainties by compiling the dataset compiled from multiple countries and regions and employing clustering analysis to elucidate the emission characteristics of diesel vehicles. Our findings reveal that oxygenated volatile organic compounds (OVOCs) and alkynes collectively accounted for approximately 60 % of total emissions in China, with methanol, formaldehyde, and acetaldehyde being among the major OVOC species identified in China, accounting for approximately 60 % of the total emitted together with alkynes, with methanol alone contributing 14.2 % of the OVOCs. Additionally, acetone and toluene were identified as characteristic typical components, contributing 1.6 % and 3.0 % to total diesel VOC emissions, respectively. Clustering results further revealed that light-duty vehicles exhibited lower proportions of these compounds, while heavy-duty vehicles, particularly China VI trucks, showed significantly higher levels. Distinct regional differences were observed, with aromatic hydrocarbons dominating non-Chinese profiles. The findings support the refinement of VOC emission inventories and the development of targeted control strategies, particularly in differentiating regulatory priorities between regions. Enhanced understanding of chemical profiles is essential for accurate source apportionment and more effective mitigation of ozone and SOA pollution.