From primary to secondary aerosol: chemical transformation and toxicity of gasoline vehicle exhaust under contrasting driving conditions.

Authors

Georgios Tsakonas, Rodopi Stamatiou, Kimmo Korhonen, Athanasios Besis, Athanasios Kouras, Ukko-Ville Mäkinen, Petteri Marjanen, Pauli Simonen, Jorma Keskinen, Karine Elihn, Constantini Samara, Antigone Lazou, Zissis Samaras

Published in

Environmental research. Pages 125881. Oct 08, 2026. Epub Oct 08, 2026.

Abstract

Secondary organic aerosol (SOA) formation from gasoline vehicle exhaust represents a significant contributor to urban air pollution, yet the integrated effects of driving dynamics, atmospheric ageing, and gas-particle interactions on aerosol toxicity remain poorly characterised. This study investigated primary and secondary particle emissions from a plug-in hybrid Euro 6 gasoline vehicle equipped with a gasoline particulate filter (GPF), tested under two chassis dynamometer driving cycles of contrasting aggressiveness: a mild Real Driving Emissions cycle (mRDE) and a highly dynamic Combined cycle, each under cold and hot engine operation. Diluted exhaust was photochemically aged in a Tampere Secondary Aerosol Reactor (TSAR) and characterised physically, chemically, and toxicologically. Chemical analysis included offline quantification of particle-bound polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), oxy-PAHs (OPAHs), and water-soluble elements, alongside real-time aerosol mass spectrometry (SP-AMS). Toxicological assessment used a mobile Air-Liquid Interface (ALI) system to expose human lung epithelial (A549) cells to fresh and aged whole exhaust and gas-phase-only streams. Atmospheric ageing consistently shifted aerosol composition from a mixed primary aerosol to an organic-dominated secondary aerosol (organic fraction increasing from ∼60% to ∼87%), enhanced ultrafine particle formation, and increased the deposited particle dose. Whole exhaust exposures produced stronger cytotoxic and inflammatory responses than gas-phase-only exposures across all conditions. For the tested vehicle and experimental conditions, driving dynamics exerted the strongest influence on biological response, while atmospheric ageing amplified the particle-associated biological response. Cold-start operation had a more moderate effect, primarily manifested through changes in gaseous emissions rather than particle toxicity.

PMID:
42849652
Bibliographic data and abstract were imported from PubMed on 09 Oct 2026.

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