Chicken dust (1)

The inhalable dust concentrations in in poultry buildings has been found to be approximately 10 and 20 times greater than for cattle and pig buildings respectively(1).

The size of these dust particles is sometimes referred to in terms of how far they can travel through the human respiratory system (2);

• Inhalable - accumulate in nostrils and nasal cavity (size greater than 100 microns)

• Thoracic - found in bronchioles (size 5-10 microns)

• Respirarable - can reach the alveoli (size less than 5 microns)

The concentrations of microorganisms in the air of chicken sheds have been found to be much greater (3) than in other animal housing, and include moulds, fungi, bacteria and bacterial endotoxins and viruses. These are often referred to as bio-aerosols and they can be adsorbed onto the surface of dust particles where they can continue to thrive. The dust particles can therefore act as vectors for pathogens, as well as being bronchial irritants in their own right. There is growing evidence that pathogens from poultry houses can travel distances much greater than 500 metres and specific pathogens and allergenic components, such as feather fragments, can cause health risks even in small quantities (3).

Although there are many different microorganisms in the air of chicken sheds, not all of them will survive the journey from the shed to neighbouring receptors, with many being destroyed by dehydration and solar ultraviolet light once they leave the warm and humid atmosphere in the shed.