Airborne Endotoxin Concentrations at a Large Open-Lot Dairy in Southern Idaho

Endotoxins are derived from grain-negative bacteria and are a potential respiratory health risk for animals and humans. To determine the potential for endotoxin transport from a large open-lot dairy, total airborne endotoxin concentrations were determined at an upwind location (background) and five downwind locations oil three separate days. The downwind locations were situated at of the edge of the lot, 200 and 1390 in downwind from the lot, and downwind from a manure composting area and wastewater holding pond. When the wind was predominantly from the west, the average endotoxin concentration at the upwind location was 24 endotoxin units (EU) m(-3), whereas at the edge of the for on the downwind side it was 259 EU m(-3). At 200 and 1390 in downwind from the edge of the lot, the average endotoxin concentrations were 168 and 49 EU m(-3), respectively. Average airborne endotoxin concentrations downwind from the composting site (36 EU m(-3)) and wastewater holding pond (89 EU m(-3)) and 1390 in from the edge of the lot: were not significantly different from the upwind location. There were no significant correlations between ambient weather data collected and endotoxin concentrations over the experimental period. The downwind data show chat the airborne endotoxin concentrations decreased exponentially with distance from the lot edge. Decreasing all individuals proximity to the dairy should lower their risk of airborne endotoxin exposure and associated health effects.