From real-driving emissions to urban air quality: composition of aged PM from modern diesel, gasoline, and CNG fueled cars and plug-in hybrid electric vehicles

Secondary aerosol emissions from vehicle exhaust often surpass primary particle emissions, yet they are not currently regulated, as they remain difficult to constrain. Here we investigate the factors driving the formation and chemical composition of secondary aerosol from light-duty vehicle exhaust emissions, focusing on the most recent Euro emission standard (Euro 6d), and including hybrid and natural gas cars. • Exhaust aged PM emissions of Euro 6d cars were about 90% lower than of older ones • Cold start aged PM emissions of Euro 6d cars, including hybrids, were important • Gasoline and CNG cars showed significant formation of ammonium nitrate • CNG organic aerosol was likely linked to low reactive species from lubricant oil • Euro 4 diesel car exhibited organic nitrate formation