Toward Recreating the Breath of Cities in the Atmospheric Simulation Chamber SAPHIR

Here, we present a framework linking emission inventories, chamber experiments, and field observations by constructing emission fingerprints of major urban sources, including vegetation, volatile chemical products, cooking emissions, and gasoline and diesel exhaust.

Applied during the CHANEL campaign in the SAPHIR outdoor chamber, these fingerprints advanced toward reproducing gas-phase mixtures representative of Los Angeles (gasoline-dominated traffic), a diesel-dominated city, and a future low-vehicle-emission scenario. The resulting mixtures generated peroxy-to-hydroperoxy radical ratios (RO₂/HO₂) close to unity, bimolecular RO₂ lifetimes comparable with urban atmospheric observations, although lower NO levels favored RO₂ + HO₂ over RO₂ + NO reactions.