Endotoxins are derived from gram-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 on three separate days. The downwind
locations were situated at of the edge of the lot, 200 and 1390
m 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 lot on the downwind side
it was 259 EU m?3. At 200 and 1390 m 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 m 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. Th e downwind data show that
the airborne endotoxin concentrations decreased exponentially
with distance from the lot edge. Decreasing an individual’s
proximity to the dairy should lower their risk of airborne
endotoxin exposure and associated health effects
