Dust and microbe levels from indoor and outdoor pig units

J.L. Morrow-Tesch1, F.M.M. .Mitloehner2, J.W. Dailey1, S.C. Wilson2, J.J. McGlone2 1USDA-ARS, Lubbock, TX; 2Texas Tech University, Lubbock, TX.

The EPA clean air act sets specific levels of acceptability for particulate matter (PM) in the air, at PM 2.5 mm that level is .065 mg/m3. Objectives of this study were to measure dust levels and microbiological contaminants on dust from pig units. A wheat field and a building at Texas Tech University were controls. Treatment sites were an indoor and outdoor gestation unit, and an indoor and outdoor farrowing unit. Dust was measured for 2 twenty-four hr periods at each site using dust meters (Dust Trak, TSI, MN). Bacterial and fungal counts were determined by taking 5 min samples with a six-stage Anderson Sampler (Anderson, GA). Plates containing media favorable to either bacterial or fungal growth were incubated 48 hr and colonies were counted. The experimental design was a repeated measure. Dust levels were higher (P < .001) on d 2 at the indoor farrowing room (mean = 0.635 vs 0.902, SE = .354 for d 1 and 2, respectively). Dust levels at the gestation units also increased (P < .001) on d 2 but were similar (P > .05) between indoor and outdoor units (mean indoor .089 vs .743, SE =.034 and outdoor .063 vs .775, SE = 034, mg/m3 for d 1 and 2 respectively). The outdoor farrowing pasture had a higher (P < .001) number of fungal colonies compared to all other environments (mean = 122.6, SE = 6.19 total counts). Most fungi were at stages 3 through 6 corresponding to PM between 3.3 and .65mm Total bacterial counts did not differ (P > .05) among environments. During d 2 all sites sampled were above the EPA limit (at PM 2.5 mm) for dust, including both control site in town and the wheat field. The outdoor farrowing pastures had the lowest dust levels for both days. Fungi are known allergens and have potential to be carried into the respiratory tract of both animals and humans on dust particles, especially at PM 4 mm or less. Our results indicate that methods of reducing particulate matter are needed in west Texas to enhance animal and worker health within indoor and outdoor pig production units.

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Revised: April 18, 2008