Factors controlling sea salt abundances in the urban atmosphere of a coastal South American megacity

► Sea salt is always present in PM2.5 and PM2.5-10 of the Buenos Aires aerosol. ► Oceanic influence under local and regional meteorological conditions is ratified. ► The ratio {[Cl−]+[Mg2+]+[Na+]}/PM best expresses variability in sea salt levels. ► Simple mathematical tools provide robust results to characterize sea salt patterns. ► Significant Cl− depletion was registered from both, PM2.5 and PM2.5-10.