Particulate matter concentrations for mono-slope beef cattle facilities in the Northern Great Plains

Mono-slope beef cattle facilities are an increasingly common housing system in the Northern Great Plains region of the U.S. Producers may maintain a deep-bedded manure pack (pack system), remove all bedding and manure from the pens weekly (scrape system), or use a combination of management styles. The objectives of this research were to determine baseline particulate matter (PM) concentrations around the immediate barn perimeter and to identify relationships between management practices and PM concentrations. PM was measured over two five-day periods at one pack system barn to determine differences in PM concentration between routine operation and a bedding event. The overall mean concentration of total suspended particulates (TSP) in the pack barn was 58.6 ±3.9 μg m^-3 during routine operation and 702.2 ±3.9 μg m^-3 during bedding events. The mean concentrations of PM less than 10 μm in diameter (PM₁₀) and PM less than 2.5 μm in diameter (PM_2.5) were 4.9 ±3.0 μg m^-3 and 17.5 ±12.1 μg m^-3, respectively, during routine operation and 29.7 ±4.6 μg m^-3 and 141.7 ±18.9 μg m^-3, respectively, during a bedding event. The PM concentrations returned to baseline within 18 h following a bedding event. In two scrape system barns, 24 h collections of PM₁₀ and PM_2.5 occurred at least twice during each quarter during a 14-month period. Daily mean concentrations of PM_2.5 and PM₁₀ in the scrape barns ranged from 10 to 14 μg m^-3 and from 25 to 28 μg m^-3, respectively, indicating relatively low PM concentrations from mono-slope beef facilities. Ambient air temperature affected PM concentration, while relative humidity, number of cattle, and wind speed were less influential on overall dust in the facilities.