International audience[1] Major summertime aerosol emission sources in Paris were assessed using a high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The application of positive matrix factorization (PMF) to the highly mass and time-resolved AMS measurements allowed the identification of primary and secondary sources of organic (OA) and sulfate aerosols. Primary anthropogenic emissions contributed on average~27% (14.7% cooking, 12% traffic) to the total organic mass, while the major contribution to the organic fraction was associated with secondary formation products. Low-volatility oxygenated OA (LV-OOA, 25.2%) and semi-volatile oxygenated OA (SV-OOA, 32.4%) factors were classified as SOA. An additional component with h...