Elucidating secondary organic aerosol from diesel and gasoline vehicles through detailed characterization of organic carbon emissions

TLDR

Emissions from gasoline and diesel vehicles are the main anthropogenic sources of reactive gas‑phase organic carbon and key precursors to secondary organic aerosol in urban areas, yet their relative importance for aerosol formation remains controversial with implications for air‑quality policy and public health. The study characterizes the chemical composition, mass distribution, and aerosol‑formation potential of gasoline and diesel vehicle emissions. Diesel exhaust is seven times more efficient at forming aerosol than gasoline exhaust, accounts for 65–90 % of vehicular‑derived SOA depending on regional fuel use, and both sources contribute substantially via aromatic and aliphatic hydrocarbons, insights that can inform regional pollution‑control policies, fuel regulations, and future measurement, laboratory, and modeling studies.

Abstract

Emissions from gasoline and diesel vehicles are predominant anthropogenic sources of reactive gas-phase organic carbon and key precursors to secondary organic aerosol (SOA) in urban areas. Their relative importance for aerosol formation is a controversial issue with implications for air quality control policy and public health. We characterize the chemical composition, mass distribution, and organic aerosol formation potential of emissions from gasoline and diesel vehicles, and find diesel exhaust is seven times more efficient at forming aerosol than gasoline exhaust. However, both sources are important for air quality; depending on a region’s fuel use, diesel is responsible for 65% to 90% of vehicular-derived SOA, with substantial contributions from aromatic and aliphatic hydrocarbons. Including these insights on source characterization and SOA formation will improve regional pollution control policies, fuel regulations, and methodologies for future measurement, laboratory, and modeling studies.