Exposure of workers to airborne microorganisms in open-air swine houses

This study quantified the levels of airborne microorganisms in six swine fa rms with more than 10,000 pigs in subtropical Taiwan. We evaluated breeding , growing, and finishing stalls, which were primarily open-air buildings, a s well as partially enclosed farrowing and nursery piggeries. Airborne cult urable bacteria, gramnegative bacteria, and fungi were placed on appropriat e media by using an all-glass impinger or single-stage Andersen microbial s ampler. Results showed that mean concentrations of culturable bacteria and gramnegative bacteria were 3.3 x 10(5) and 143.7 CFU/m(3), respectively. Th e concentration of airborne culturable fungi was about 10(3) CFU/m(3), with Cladosporium the predominant genus. The highest airborne levels of cultura ble bacteria and gram-negative bacteria were identified in the finishing un its. The air of the nursery stalls was the least contaminated with culturab le and gram-negative bacteria. Irregular and infrequent cleaning, high pig density, no separation of wastes from pen floors, and accumulation of water as a result of the processes for cleaning and reducing pig temperature pos sibly compromise the benefits of the open characteristic of the finishing u nits with respect to airborne bacterial concentration.