Farmers' exposure to airborne microorganisms in composting swine confinement buildings.

Farmers' exposure to airborne microorganisms was studied in 12 composting swine confinement buildings and in 7 buildings with traditional slatted-floor pit systems. Airborne cultivable mesophilic, xerophilic, and thermotolerant fungi, mesophilic bacteria, and thermophilic actinobacteria were determined with a six-stage impactor. Furthermore, the total concentrations of microorganisms were determined with filter sampling and direct count using a microscope. In swine confinement buildings where the composting system was functioning properly, the concentrations of microorganisms were 10-1000 times higher than in traditional swine buildings. High concentrations of thermotolerant fungi and thermophilic actinobacteria (up to 10(5) CFU/m(3)), which have been considered to be the main causative agents of farmer's lung, were found in the composting swine confinement buildings that were studied. The conclusion was reached that farmers are exposed to high concentrations of fungal and actinobacterial spores also in swineries, at least in composting confinement buildings. Therefore, personal protection is strongly recommended in composting swineries, especially during the turning of the compost bed.