The present study aimed to evaluate microbiological pollution of air with microorganisms belonging to different taxonomic and physiological groups, and to examine whether the effect of the municipal landfill site in Krzyż changes at various study sites located: in so called "zero zone" (operating landfill), at different distances from the landfill and in Tarnów. Municipal landfill site for the city of Tarnów is located in north-eastern part of the city, in Krzyż district, on the ground gently-sloping towards South-East. The present microbiological studies showed wide differences in numbers of bacteria, ranging from 5 x 101 to 439 x 104 colony-forming units (e.f.u.) per 1 m1 of air. Abundance of bacteria was the highest in summer, i.e. in July, August and September (maximum of 7.44 x 101 e.f.u, in August), and at the sites No. 5 and 2 (maximum of 10.46 x 104 e.f.u. at site No. 5).