this paper presents preliminary results from a year-long indoor bioaerosol monitoring performed in three working environments of a municipal composting facility treating green and organic waste. composting, whereby organic matter is stabilized through aerobic decomposition, requires aeration, causing the dispersion of microbial particles (microorganisms and associated toxins). waste can, therefore, become a potential source of biological hazard. bioaerosol samples were collected on a monthly basis. through a comparison of results obtained using two samplers - the surface air system duo sas 360 and the biosampler - the study aimed at assessing the presence of biological pollutants, and at contributing to the definition of standard sampling methods for bioaerosols leading, eventually, to the establishment of exposure limits for these occupational pollutants.