Ambient air pollution in major urban areas leads to millions of premature deaths in the United States each year, primarily from particulate matter and ozone. A major unknown is the role of VCPs in the formation of secondary organic aerosol (SOA) in urban areas. This project aims to expand the breadth of knowledge gained at a planned ground site deployment during the AEROMMA campaign. The project team will collect size resolved aerosol particle samples at the two field sites that are being run in coordination with AEROMMA and the New York City metropolitan Measurements of Emissions and TransformationS (NYC-METS) campaign. This additional information will provide improved understanding of SOA formation and sources. Results from planned project experiments will provide a more complete view of the aerosol composition and the role of VCPs in SOA formation in an urban environment.