Identification of risk factors for sub-optimal housing conditions in Australian piggeries: Part 4. Emission factors and study recommendations.

The internal concentrations and emission rates of ammonia (NH3), total bacteria, respirable endotoxins, and inhalable and respirable particles were monitored in 160 piggery buildings in four states of Australia (Queensland, Victoria, Western Australia, and South Australia) between autumn 1997 and autumn 1999. Emissions were calculated for individual buildings as a product of internal concentration and ventilation rate, which were estimated by a carbon dioxide balance method. Relative humidity and temperature were also measured. The overall mean emission rates of NH3, total bacteria, respirable endotoxins, inhalable particles, and respirable particles per 500 kg live weight from Australian piggery buildings were 1442.5 mg h(-1), 82.2 x 10(6) cfu h(-1), 20.1 x 10(3) EU h(-1), 1306.7 mg h(-1), and 254.7 mg h(-1), respectively. Internal concentrations of key airborne pollutants have been reported in companion articles. Building characteristics and management systems used in the piggeries were documented at the time of sampling and used in the subsequent statistical modeling of variations in pollutant emission rates. The emissions model used all statistically significant factors identified during prior modeling conducted for individual pollutant concentrations and ventilation airflow. The identification of highly significant factors affecting emission rates and internal concentrations should aid the development of strategies for the industry to reduce emission rates from individual buildings, thus improving the environmental performance of piggery operations. In the second part of the article, specific recommendations are made based on the overall study results.