Identification of two main origins of intermediate-volatility organic compound emissions from vehicles in China through two-phase simultaneous characterization

Area of Science:

• Atmospheric Chemistry
• Environmental Science
• Automotive Engineering

Background:

• Intermediate-volatility organic compounds (IVOCs) from vehicle emissions contribute to air pollution.
• Understanding IVOC partitioning between gas and particle phases is crucial for accurate emission assessments.

Purpose of the Study:

• To characterize gas- and particle-phase IVOC emissions from gasoline and diesel vehicles.
• To identify the primary sources of IVOCs in vehicle exhaust.
• To assess the impact of IVOCs on secondary organic aerosol (SOA) formation.

Main Methods:

• Dynamometer testing of gasoline and diesel vehicles in Guangzhou, China.
• Simultaneous characterization of gas- and particle-phase IVOCs.
• Chemical composition and volatility distribution analysis.

Main Results:

• Diesel vehicles emitted ~16 times more IVOCs than gasoline vehicles, primarily in the particle phase (unresolved complex mixture).
• Gas-phase IVOCs originated mainly from fuel, while particle-phase IVOCs were linked to lubricating oil.
• IVOCs significantly contributed to secondary organic aerosol (SOA) formation, exceeding primary organic aerosol (POA) emissions.

Conclusions:

• Lubricating oil is a critical source of particle-phase IVOCs.
• Stricter emission standards, particularly China VI, are necessary to effectively reduce IVOC emissions and subsequent SOA production.
• Accelerating the adoption of the latest emission standards is vital for mitigating vehicle-related air pollution in China.