Comparison with SOA mass concentrations reveals that, despite the addition of marine benzene and toluene emissions to the model, sulfate dominates the secondary aerosol composition in both polar regions. Indeed, the calculated emission fluxes of DMS were 20-fold those of benzene and toluene during both cruises . Consequently, cruisemean and cruise-maximum benzene and toluene emissions increased total secondary aerosol (SOA + non-sea-salt sulfate aerosol) by less than 2 % in all model runs and for both polar oceans. Even though benzene and toluene do not contribute as much to aerosol mass compared to DMS, they are a source of highly oxygenated organic molecules that condense onto existing particles and contribute to aerosol growth . Oxidised aromatics alter particle properties and may help explain the lower-than-expected particle hygroscopicity over the Southern Ocean .