The objective of this study was to quantify, size, and examine the composition of particulates found in ambient aerosolized dust of four large feedyards in the Southern High Plains. Ambient air samples (concentration of dust) were collected upwind (background) and downwind of the feedyards. Aerosolized particulate samples were collected using high volume sequential reference ambient air samplers, PM_(10) and PM_(2.5), laser strategic aerosol monitors, cyclone air samplers, and biological cascade impactors. Weather parameters were monitored at each feedyard. The overall (main effects and estimable interactions) statistical (P < 0.0001) general linear model statement (GLM) for PM_(10) data showed more concentration of dust (mu g/m~3 of air) downwind than upwind and more concentration of dust in the summer than in the winter. PM_(2.5) concentrations of dust were comparable for 3 of 4 feedyards upwind and downwind, and PM_(2.5)Concentrations of dust were lower in the winter than in the summer. GLM (P < 0.0001) data for cascade impactor (all aerobic bacteria, Enterococcus spp, and fungi) mean respirable and non-respirable colony forming units (CFU) were 676 + - 74 CFU/m~3, and 880 + - 119 CFU/m~3, respectively. The PM_(10) geometric mean size (+ -GSD) of particles were analyzed in aerosols of the feedyards (range 1.782 + - 1.7 mu m to 2.02 + - 1.74mu m) and PM_(2.5) geometric mean size particles were determined (range 0.66 + - 1.76 mu m to 0.71 + - 1.71 mu m). Three of 4 feedyards were non-compliant for the Environmental Protection Agency (EPA) concentration standard (150 mu g/m~3/24 h) for PM_(10) particles. This may be significant because excess dust may have a negative impact on respiratory disease.
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