The air found in a shearing shed environment is normally contaminated with many different airborne substances. These contaminants include dust (predominantly organic), bioaerosols (fungi and bacteria), and gases (ammonia and carbon monoxide). Respiratory disorders have been associated with exposure to the types of contaminants found in a normal sheep shearing environment. Twenty nine shearing sheds in the state of New South Wales in Eastern Australia were sampled for concentrations of airborne contaminants. Based on the results of this study the following recommendations are made for the shearing industry: under the current dust and bioaerosol exposure standards there are no requirements to investigate mechanical ventilation to reduce airborne contaminants and there is no need for respiratory protection in any of the monitored sheds. However, it is recommended that if a person has a known predisposition to respiratory illness/stress they should be closely monitored while working in a shearing shed. There are issues raised in this thesis that require further research including the need for an epidemiological study on the health of people working in shearing sheds in relation to their respiratory health. The monitoring of shearing sheds in other regions of Australia needs to be undertaken and based on available literature similar studies are also needed in other livestock industries in Australia. / Doctor of Philosophy (PhD)