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 infl ammatory reactions in the respiratory tract when inhaled. To assess daily fl uctuations 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. Th e 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 higher 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 emission rate and meteorological conditions.

Air pollution from livestock farms, and asthma, allergic rhinitis and COPD among neighbouring residents

“…Endotoxin levels that have been shown to cause acute respiratory effects can be found several 100 m downwind of animal farms 5 35 36. Therefore, as in the study by Radon et al ,11 we used a distance of 500 m to define our exposure variables.…”

“…Swine and poultry farmers are at increased risk of developing respiratory symptoms and accelerated lung function decline associated with COPD and non-allergic asthma due to high levels of endotoxin and other microbial components in stable dust 1–3. Although ambient exposure levels in the surroundings of animal stables are considerably lower than levels inside stables,4 5 they can induce clinically important symptoms 6. It is not known whether indoor exposure levels in non-farm residences are influenced by neighbouring animal farms.…”

Concentrations of airborne endotoxin and microorganisms at a 10,000-cow open-freestall dairy1

“…The increase in airborne endotoxin concentration toward the evening and night can be attributed to increased animal activity and slower wind speed. Whereas airborne endotoxin concentrations are generally increased in the immediate downwind environment at dairies, both predicted and measured concentrations have been shown to decrease with distance and reach background concentrations within 500 to 2,000 m (Dungan and Leytem, 2011). Whereas the particle-size collection characteristics of the open-face samplers are unknown, the button aerosol samplers were used to enhance the collection of particles with an aerodynamic diameter of <100 µm.…”

“…In the western United States, the predominant dairy systems are open-lot, where cattle are housed in large pens, or open-freestall, where the cows are housed indoors for much of the time. Because these management systems are very different, there is potential for large differences in bioaerosol emissions at these 2 types of production facilities (Dungan and Leytem, 2011).…”

Ambient Ammonia Exposures in an Agricultural Community and Pediatric Asthma Morbidity

“…During manure storage as well as application to farmlands, a variety of chemical and biologic pollutants are released to the atmosphere, and resultant impacts on regional air quality have been observed. 1-5 …”