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

Atmospheric ageing of gasoline vehicle exhaust increases organic aerosol fraction from about 60% to 87%, enhances ultrafine particle formation, and raises deposited particle dose.

• Why it matters: Understanding how driving conditions and atmospheric processes influence aerosol toxicity is crucial for assessing urban air pollution health risks, yet this interaction remains poorly characterized.
• What they did: Researchers tested a Euro 6 gasoline vehicle under two driving cycles and different engine temperatures, then aged the exhaust in a reactor, analyzing chemical composition and toxicological effects on human lung cells.
• The result: Driving dynamics had the strongest impact on biological responses, with atmospheric ageing amplifying particle-associated toxicity, indicating that real-world driving and atmospheric processes jointly influence health risks.