An assessment of potential exposure to bioaerosols among swine farm workers with particular reference to airborne microorganisms in the respirable fraction under various breeding conditions

Abstract

The project was aimed at evaluating the potential occupational exposure of swine farm workers to dust and microorganisms present in piggery bioaerosols (especially in its respirable fraction) under various breeding conditions. Sampling was carried out in 14 buildings located at 13 pig breeding and production farms in Poland. Concentrations of inhalable and respirable dusts in the air of the piggeries were low (means, respectively, 1.76 and 0.23 mg/m3). The concentration of microorganisms was generally high (mean = 3.53 × 105 cfu/m3). More than 96% of determined microorganisms were bacteria (mean = 3.42 × 105 cfu/m3). The fungal concentration was distinctly lower (mean = 2.71 × 103 cfu/m3). The concentration of bacteria in the respirable fraction of bioaerosol (mean = 1.51 × 105 cfu/m3) made up for 48.2% of their total concentration, while the level of fungi in that fraction (mean = 1.50 × 103 cfu/m3) formed 68.8% of the total fungal concentration. The concentration of inhalable dust was significantly modified by the type of breeding system. The factors that significantly affected the total concentrations of microbes and bacteria, as well as their levels in the bioaerosols’ respirable fraction were as follows: herd size, breeding system, feeding method and the type of ventilation system. In the case of fungi, these were the livestock breeding system and the feeding method. Moreover, there was a high positive correlation of inhalable dust concentrations with the fungal concentration, CO2 and relative humidity. A negative correlation was found between concentrations of each microbe group and the airflow velocity. Swine farm workers are exposed to relatively low dust concentrations and high concentrations of microorganisms, bacteria in particular. Fungi, to a much larger extent than bacteria, are correlated with the respirable particles of a piggery bioaerosol, which may harm the respiratory system of exposed workers.