Highlights • High temporal resolution aerosol data were collected in two Adriatic port cities. • Shipping contribution to particle concentration of different sizes was investigated. • Contributions to nanoparticles were significantly larger compared to other sizes. • Relative contributions to nanoparticles were 7.4% in Venice and 1.8% in Rijeka. • Contributions to PM1, PM2.5 and PM10 were about 2% in Venice and <0.2% in Rijeka. See more