The aim of the study was to determine air pollution over the sea surface (North Sea and Baltic Sea) compared to the situation in ports, as well as to examine the impact of ships on the level of particulate matter (PM) concentration. The measurements, made during the two-week cruise of the tall ship Fryderyk Chopin, demonstrated that the principal source of PM emission over the sea surface are passing ships equipped with internal combustion engines, including quite numerous units powered by marine oil. The highest pollution levels were observed in locations distant from the coast, with increasing concentrations when other ships were approaching. During the cruise, at least two places were identified with increased PM concentration (18&ndash / 28 &mu / g/m3 for PM10 and 15&ndash / 25 &mu / g/m3 for PM2.5) caused by passing ships. The share of PM2.5 fraction in the general PM concentration in these places increased from 70&ndash / 72% to 82&ndash / 85%, which means that combustion emission dominated. In turn, measurements made in ports (Copenhagen and Kołobrzeg) showed lower levels of air pollution and indicated a typical variability of the PM concentrations characteristic for land areas. The results confirm the need for determining suitable solutions for sustainable sea transport.