title: Ambient endotoxin concentrations and assessment of offsite transport at open-lot and open-freestall dairies.
abstract: Endotoxins are derived from gram-negative bacteria and are a potent inducer of inflammatory reactions in the respiratory tract when inhaled. To assess daily fluctuations of airborne endotoxin and their potential for transport from dairies, endotoxin concentrations were monitored over an 8-h period at upwind (background) and downwind (5 m from edge of dairy) locations on three separate days at two dairies. The dairies consisted of an open-lot or an open-freestall production system, both of which were stocked with 10,000 milking cows. Upwind concentrations were stable throughout the sampling period, averaging between 1.2 and 36.8 endotoxin units (EU) m(-3), whereas downwind concentration averages ranged from 179 to 989 EU(-3). Downwind endotoxin concentrations increased with wind speed, animal activity, and lot management practices, resulting in concentrations up to 136-fold hi gher than upwind concentrations. An area-source model was used to predict downwind ground-level endotoxin concentrations at distances up to 2000 m from the production facilities. Predicted concentrations decreased with distance and reached background levels within 500 to 2000 m, depending on the source emision rate and meteorological conditions.
authors.affiliation: USDA-ARS, Northwest Irrigation and Soils Research Lab., 3793 North 3600 East, Kimberly, ID 83341, USA. robert.dungan@ars.usda.gov
authors.forename: Robert S
authors.initials: RS
authors.lastname: Dungan
authors.forename: April B
authors.initials: AB
authors.lastname: Leytem
mesh_terms: D000393:Air Pollutants / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D003612:Dairying; D004731:Endotoxins / Q000378:metabolism*; D007061:Idaho; D008962:Models, Theoretical
chemical_list: D000393:Air Pollutants; D004731:Endotoxins