Formation and Evolution of Secondary Organic Aerosol Derived from Urban Lifestyle Sources:

20 Both vehicle exhaust and cooking emission are closely related to the daily life of city dwellers, which are considered as 21 major sources of urban secondary organic aerosol (SOA). Here, we defined the SOA derived from vehicle exhaust and cooking 22 emission as "Urban Lifestyle SOA", and simulated their formation using a Gothenburg potential aerosol mass reactor (Go: 23 PAM). After samples had been aged under 0.3-5.5 days of equivalent photochemical age, these two urban lifestyle SOA 24 showed markedly distinct features in SOA mass growth potentials, oxidation pathways and mass spectra. The SOA/POA mass 25 ratios of vehicle groups (107) were 44 times larger than those of cooking groups (2.38) at about 2 days of equivalent 26 photochemical age. It reveals that organics from vehicle may undergo the alcohol/peroxide and carboxylic acid oxidation 27 pathway to produce abundant less/more oxidized oxygenated OA (LO-OOA and MO-OOA), and only a few primary 28 hydrocarbon-like organic aerosol (HOA) remains unaged. In contrast, organics from cooking may undergo the 29 alcohol/peroxide oxidation pathway to produce moderate LO-OOA, and comparable primary cooking organic aerosol (COA) 30 remains unaged. Our findings provide an insight into atmospheric contributions and chemical evolutions for urban lifestyle 31 SOA, which would greatly influence the air quality and health risk assessments in urban areas. 32 https://doi.org/10.5194/acp-2021-20 Preprint. Discussion started: 22 February 2021 c © Author(s) 2021. CC BY 4.0 License.