LC-HRMS non-target analysis reveals contrasting organic aerosol composition between urban and agricultural Po Valley sites (acp.copernicus.org)

• First molecular-level OA characterization in the Po Valley using LC-HRMS non-target analysis.
• Biogenic SOA dominates summer; combustion-related CHNO compounds dominate winter.
• Pesticides significantly influence rural OA composition, peaking in May during low PM2.5.

"A one-year LC-HRMS (Orbitrap) non-target analysis of PM2.5 from Milan (urban) and Schivenoglia (rural agricultural) in the Po Valley, Italy, identified thousands of organic compounds. Hierarchical clustering revealed seasonal patterns: biogenic secondary organic aerosols (CHO, CHOS) dominate summer, while combustion-related nitrogen-containing compounds (CHNO) peak in winter. At the agricultural site, pesticides significantly influence aerosol composition, especially in May when PM2.5 levels are low, indicating potential health risks despite apparent good air quality."