DETERMINANTS OF CULTURABLE BIOAEROSOL CONCENTRATIONS IN DAIRY BARNS

The concentration of bioaerosols to which dairy farmers are exposed is potentially related to environmental factors, such as climatic conditions and individual management practices. An unprecedented heavy rainfall that was 250% of normal during the growing season of feed and bedding materials provided an unique opportunity for study. Individual dairy management practices differ as to barn construction, type of ventilation system, storage moisture of feed rations, quality of bedding materials, and animal density. The aim of this study was to identify the environmental factors affecting the concentrations of culturable bioaerosols in dairy barns. In this cross-sectional study of 48 dairy barns, area samples were collected using all-glass impingers. Culturable bioaerosols were analyzed to determine airborne concentrations of yeasts, molds, mesophilic bacteria, and thermophilic bacteria. The time-weighted geometric mean concentrations of these bioaerosols collected over the work-shift were 1.8 × 10 4 cfu/m