Long-term trends of benzo(a)pyrene concentration on the eastern coast of the Baltic Sea

Concentration of benzo(a)pyrene (B(a)P) was investigated in atmospheric air at Preila background station located on the eastern coast of the Baltic Sea in 1980–2002. A significant difference in daily concentration of benzo(a)pyrene, reaching more than two orders of magnitude, was determined during the period of investigation. The variability of benzo(a)pyrene daily concentration was considered. The main part of extreme benzo(a)pyrene daily concentration of over 5 ng m−3 was related to the air masses coming to the background site from W-SW to N-NW over the period of 1980–1994. Owing to the variability of benzo(a)pyrene daily concentration, the monthly concentration of benzo(a)pyrene in atmospheric air of the background site varied from 0.18 to 3.30 ng m−3 in cold season and from 0.02 to 1.72 ng m−3 in warm season. A slowly decreasing trend of benzo(a)pyrene monthly concentration was determined in both seasons during the whole period of investigation. Comparison of B(a)P monthly concentration determined at Preila background station with that in other countries since 1994 (according to the EMEP program) has shown that monthly concentration of benzo(a)pyrene is nearly of the same level in the Czech Republic and it is by one order of magnitude higher than at Scandinavian background stations. The course of carcinogen concentration at Preila background station is similar to that of Swedish stations with tendency to decrease from 1999.