Understanding the origin and type of organic aerosol (OA) is essential for determining its impact on air quality, climate, and health. In this study, we focus on determination of the source/state of OA analyzed using aerosol mass spectrometry. This was performed both online, directly at the station, and offline in the laboratory using analyses of fine aerosol (PM1) collected on filters. Parallel sampling for online and offline analysis allows us to subsequently assess the validity of given methods.