Microbiol. contamination of air at the municipal sewage treatment plant in Slupsk and in its vicinity was detd. in autum and spring time 2007-2008. The total number of bacteria reached 10(4), fungi 10(3), and actinomycetes 10(2) colony-forming units in 1 m(3). The highest concns. of bacteria and actinomyces were obsd. at compost facility. A low concn. of fungal spores was found at all the sampling points. Mannitol-positive staphylococci contributed to the strong air pollution at the composting plant and beyond the sevage treatment plant. The number of Salmonella bacilli and Enterococcus bacteria remained at a very low level. The bacteria and mannitol-negative staphylococci were isolated only occasionally.