An Urban Emission Inventory Approach for Source Specific Atmospheric Chamber Studies

Urban pollution poses one of the largest threats to human health worldwide. A significant portion of this pollution is secondary, formed through atmospheric chemical reactions of emitted trace gases, with secondary organic aerosol (SOA) and ozone (O₃) being major contributors to health impacts in urban areas. While decades of air quality regulations have significantly reduced motor vehicle emissions of organic compounds that are precursors to secondary pollution, recent focus has shifted to understudied urban sources such as volatile chemical products (VCPs) and cooking emissions. These sources are complicated and challenging to replicate in chamber experiments, which typically focus on single-compound scenarios, thus limiting their comparability to real-world urban environments.

In this study, we utilized emission inventories and developed an approach to reduce the number of compounds that represent each urban source, including VCPs, gasoline, diesel, and cooking, by generating chemical fingerprints representing 80% of the overall reactivity and SOA formation potential of each urban source. These fingerprint solutions were then injected into the atmospheric simulation chamber SAPHIR to explore their potential for SOA and O₃ formation. We conducted experiments simulating each source at various NOx exposures, as well as mixed systems to simulate the urban atmosphere of US and European cities. Finally, we contextualize our findings by comparing them with data from the Atmospheric Emissions and Reactions Observed from Megacities to Marine Areas (AEROMMA) mission, offering insights into the dynamics of urban air pollution.