Control of emissions from livestock buildings and the impact of aerial environment on health, welfare and performance of animals - a review

High concentrations of gases and airborne particles often occur in buildings for poultry and pigs which can have adverse effects on the health of both workers and animals. The airborne pollutants mainly have negative effects on respiratory systems which can compromise health and production efficiency of livestock. Emissions of airborne pollutants from animal buildings may also have negative effects on the outdoor environment. There is therefore a demand to reduce the release and concentrations of airborne pollutants in animal buildings. The release of gases and airborne particles in animal buildings is complex process and is influenced by several factors in the building environments. This chapter reviews health effects of airborne pollutants on humans and animals in buildings for poultry and pigs. The different factors and processes influencing the release and concentrations of airborne pollutants are discussed. Factors which influence the release and concentration of ammonia in animal buildings are mainly related to the nitrogen content of feedstuff, exposure of faeces and urine (hygiene levels), manure and air temperatures, ventilation and heat balance. High levels of carbon dioxide are usually an indication of low ventilation rates. The major part of dust in animal buildings is organic. Investigations in pig buildings have shown that the generation of dust is influenced by hygiene levels as well as the number and the weight of pigs. Settling of dust is an important mechanism in the mass balance of dust. A major part of the generated dust settles on different surfaces inside the buildings. Investigations have proved that the activity in pig and poultry buildings has a strong influence on the concentration of dust in the air. A technique that directly can reduce the concentrations of dust is water and oil mixture spraying. In addition, the proper management of risk factors for sub-optimal air quality is the most effective way of reducing airborne pollutant levels in livestock buildings.