Measurement report: Emission factors and organic aerosol source apportionment of shipping emissions in the coastal city of Toulon, France

Abstract. Maritime transport has a significant impact on local air quality, especially in port areas. Ship emissions are recognized as major contributors to air pollution, comparable to road transport emissions. This study, conducted in 2021 in Toulon, a port city on the French Mediterranean coast, assessed emissions from shipping one year after the implementation of IMO2020 sulfur regulations. Emission factors (EFs) for pollutants such as SO₂, NO_X, CO, NO, CH₄ and PM as BC, organics (Org), SO₄^2-, NO₃^-, NH₄⁺ and PAHs were measured, as well as the particle number concentration (PN). IMO2020 regulation induced a significant reduction in sulfur-related emissions while other pollutants like soot, organics and PAHs remained at pre-regulation levels. Positive Matrix Factorization (PMF) of High-Resolution Time-of-Flight Aerosol Mass Spectrometer measurements of non-refractory PM₁ organic aerosol (OA) was used to investigate the shipping contribution to local air quality. PMF could separate road and marine transport emissions, revealing a shipping contribution to the total OA fraction of 11.2 %. Eight factors were resolved: three shipping-associated OA, a Hydrocarbon-like OA (HOA), a Cooking-like OA (COA), an Oxidized Hydrocarbon-like OA (OxHOA), a Less Oxidized OA (LOOA), and a More Oxidized OA (MOOA). Shipping and HOA factors were the major contributor to ultrafine particles and they represented the biggest emitter of alkylated PAHs (APAHs) (51.9 %). These findings underscore the importance of distinguishing shipping emissions in port areas and advanced source apportionment methods’ potential to improve emissions monitoring strategies, especially as the Mediterranean region prepares for Emission Control Area regulations in 2025.