The aim of the study was to recognize exposure to biological agents in the air of waste sorting plants. This publication contains the characteristics of technical solutions in use during sorting of waste and the results of quantitative analysis in terms of the presence of moulds and inhalable dust in the air.The study was conducted in the summertime inside two waste sorting plants with different production capacity ("big" and "small"). To evaluate inhalable dust in the air, 53 samples were collected using personal samplers on glass fiber filters. To assess mycological contamination of the air, 30 triple samples were directly collected on Petri dishes (Malt Extract Agar medium), using the volumetric impact method in the worker's respiratory zone. Samples were incubated for 5 days at 30 degrees C. Outcomes of the total number of moulds were provided in cfu/m3 (cfu--colony forming units).The mean concentration of inhalable dust, determined in the "big" waste sorting plant, was 2.38 mg/m3 and in the "small" plant 1.12 mg/m3. The quantitative analysis revealed the following values of the total number of moulds present in the air: 1) "big" waste sorting plant, 2.9 x 10(4) cfu/m3 (work premises) and 3.6 x 10(3) jtk/m3 (office premises); 2) "small" waste sorting plant, 7.8 x 10(4) cfu/m3 (work premises) and 2.5 x 10(3) jtk/m3 (office premises).Mould concentrations determined in the environment of waste sorting plants were high. To protect health of workers in this kind of plants, preventive programs focused on the protection of the skin and respiratory system should be implemented. Offices should be properly isolated from work premises to minimize spreading of inhalable dust.