Bioaerosol emissions from composting facilities as a potential health risk for composting workers

Exposure to bioaerosols in the occupational environment is associated with a wide range of adverse health effects. Composting is biological decomposition of organic waste material which necessarily leads to proliferation of microorganisms with in the composting substrate, it is potential for these microorganisms to become airborne as the compost is being turned and screened. Exposure to bioaerosols could be a cause of respiratory symptoms and lung function impairment. The aim of this study was to assess worker exposure to bioaerosols emitted from a urban waste composting facility in Isfahan, Iran. To assess the concentration of bioaerosols, fungi and bacteria were collected using an Andersen biosampler from 8 point on–site and one point off-site as background sample. Air temperature, relative humidity and wind speed were also recorded at the time of sampling. Peak levels of both microorganisms were measured at composting pile windrows followed by screening site and storage piles. Total bacterial and fungal concentrations averaged 9307 cfu/m 3 and 764 cfu/m 3 for composting piles and 1113 and 130 cfu/m 3 for background samples, receptively. Concentration of fungi was lower than bacteria during all stages of the composting processes. There is a significant decreasing of bioaerosol concentrations with the distance of composting piles and 250 m downwind from the compost piles was the distance by which concentrations were found to reach the background concentrations. These results indicated that compost workers are at risk of developing chronic and acute respiratory health effects due to the exposure to bioaerosols from composting process. Key-words: composting process, bioaerosol, emission, health risk, fungi, bacteria