Studies in the USA, Sweden and the Netherlands have shown that workers in enclosed piggeries have high levels of respiratory injury, apparently caused or exacerbated by inhaled factors in their working environment. Three types of airborne hazard are known in piggeries — gases, dusts and infectious agents such as bacteria.
Of the gases that accumulate in enclosed piggeries, carbon dioxide, methane and carbon monoxide, are asphyxiating, while dihydrogen sulphide and ammonia are irritant and toxic. The long-term effects of exposure to subclinical concentrations of these gases and their rôle in producing chronic respiratory effects in workers are unknown.
Studies have shown that organic dusts occur in enclosed piggeries at undesirably high concentrations and that a relatively high proportion of this dust is respirable. The components of these dusts consist mostly of fractions of foodstuffs and pig faeces but with significant amounts of pigskin and pig gut epithelial cells. Also microbes, especially fungi and bacteria, have been found to be numerous. Different components of piggery dust could be irritant, toxic, allergenic, inflammatory or infectious, and a single component could have more than one of these effects. Studies suggest that bacterial endotoxins are present in the dust of enclosed piggeries at concentrations that could induce respiratory diseases in workers.
It is recommended that in designing piggeries more attention should be given to the health and comfort of piggery workers and that a survey be carried out immediately to assess the level of respiratory disease in British piggery workers. Also a greater effort should be put into the health education of piggery workers and managers and of those involved in piggery design. Practical and effective systems for the control of dust and gas levels in piggeries, and appropriate management techniques, need to be developed for new piggeries and for already constructed buildings, and the financial cost of poor control of dust and gas contaminants brought home to producers. Overall, a watching brief needs to be maintained on trends in the design and management of pig rearing systems for their likely impact on workers' health.