Bioaerosols have become a major health concern in the waste industry, and the Environment Agency regards their generation and dispersion as a key issue in the design and operation of composting plants. The bioaerosols generated at composting plants are mainly airborne micro-organisms and organic constituents of the feedstock materials. These are released during operations where the movement of material is involved, mainly during fresh waste delivery, shredding, compost pile turning and compost screening. Amongst the bioaerosols, Aspergilius fumigatus has been the most widely studied, because of its abundance in composting piles and its potential negative effects on human health. Aspergilius fumigatus is a very common saprophytic mould that grows in composting piles since its optimum growing conditions, i.e. temperatures between 37 and 43℃, and substrates with a high amount of carbon are characteristic of many composting operations. This mould forms spores, around 2 μm in diameter, which can be very easily carried by the wind to distances ranging from a few hundred metres to several kilometres. The small size of these spores means that they can enter the lungs easily if inhaled, becoming a potential cause of infections in immunodepressed people and causing allergic responses in others.
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