Occupational bioaerosol exposure in composting plants

The worldwide waste treatment industry VEOLIA ENVIRONNEMENT carried out a bibliographical review of the occupational exposure to bioaerosols in composting plants, which is based on a literature survey conducted since 1993 by the French Health and Waste Network. Composting is an aerobic biological waste treatment. Bioaerosol released from composting contains mesophilic and thermophilic microorganisms. Bacteria, fungi, particularly Aspergillus fumigatus, and thermophilic actinomycetes are the most frequent microorganisms detected in the ambient air of composting plants. These microorganisms are known to be allergenic agents. Viruses and parasites have never been investigated in the air of composting plants. Microorganism concentrations in the air vary with the seasons, the type of composting process and the waste composted. Maximum microorganism concentrations (10 3 -10 5 cfu/m 3 ) are detected in the loading area and during waste crushing and windrows turning. Mycotoxins produced by Aspergillus fumigatus or Penicillium that are present in the ambient air of some composting plants are correlated with high concentrations of fungi spores. High concentrations of Gram negative bacteria (10