Air microbial quality of the municipal landfill site and in its surroundings was evaluated. Adverse impact of the municipal landfill site in Tarnow on the atmospheric environment was noted, despite the use of correct waste disposal technology. The sampling site and season of the year significantly affected the numbers of various groups of air microorganisms at the municipal landfill site and in its vicinity. For most cases, the effects of the sampling site on the microbial numbers were stronger than that of the season of the year. In this study, higher microbial numbers were observed at the sampling sites located in the area of the active landfill site compared to those located in its vicinity. The obtained results indicate, that despite the lack of current limits for bioaerosol levels the landfill site, even after its closing and reclamation, may still not be a suitable place for any public usage. Therefore, any regular microbiological studies of air should be carried out for a long time both at the area of landfill site and in its vicinity. These results could allow to define the time, when the landfill site become stable, regarding the numbers of microorganisms released to air.