Occupational exposure to bioaerosols during monk parakeet nest removal in urban parks

Monk parakeets have established large urban populations in several European cities, where management of this invasive species includes removal of large communal nests from trees. These work activities may generate exposure to bioaerosols. The aim of this study was to characterize monk parakeet nests as a source of airborne biological pollutants and to assess associated occupational exposure to fungi, bacteria, and endotoxin among park workers removing these nests. Nest material and air samples were analyzed for endotoxin, fungi, and bacteria. Microorganisms were identified to species level using MALDI-TOF MS, and the total inflammatory potential of collected air samples was assessed in vitro. Nest material contained high concentrations of endotoxin, fungi, and bacteria. During nest removal activities, workers were exposed to significantly elevated concentrations of fungi and endotoxin compared with background levels, with the highest fungal exposure occurring during cutting tasks. A total of 43 fungal species belonging to 16 genera were identified, including numerous Aspergillus and Penicillium species, several of which were detected only during work activities and in nest samples. Six fungal species belonged to risk group 2 (RG2). In total, 91 bacterial species were identified, of which 74 were airborne, and 14 species were classified in RG2 and included e.g. Enterobacter hormaechei, Psychrobacter pulmonis, Raoultella ornithinolytica. The total inflammatory potential correlated significantly with both fungal and endotoxin concentrations. Endotoxin exposure exceeded the suggested health-based guidance value. In conclusion, in the studied urban environment, monk parakeet nests represent a previously unrecognized source of airborne microorganisms and endotoxin. Nest removal constitutes an occupational exposure scenario associated with inflammatory and allergic respiratory risks.