Wintertime Factors Affecting Contaminant Distribution in a Swine Farrowing Room

Abstract

An estimated 200,000 to 500,000 U.S. workers in concentrated animal feeding operations (CAFOs) are at risk of adverse respiratory outcomes from exposures to indoor contaminants. In the wintertime, general ventilation is minimized in the Midwest due to high heating costs required to maintain indoor temperatures optimal for animal production. Pit fans typically operate to exhaust under-floor manure pits, but little other fresh air intake exists. Many operators believe that these systems are sufficient to reduce contaminant concentrations within the building during winter. Investigating whether these pit fans provide sufficient protection against classic CAFO contaminants during minimal wintertime ventilation was warranted. Direct-reading instruments were used to measure and record concentrations of multiple contaminants using both fixed-area and mobile contaminant mapping in a farrowing room during a Midwest winter. With the exception of CO, concentrations were significantly (p < 0.001) higher with the pit fan off compared with those with the pit fan on. Additional analyses identified that significant changes (p < 0.001) in mean room concentrations of respirable dust (decreased, 77% with pit fan off and 87% with pit fan on) and CO₂ (increased, 24%) over the 5-hr study periods and that multiple fixed-area monitors rather than the much-used, single center-of-room monitor provided a more conservative (e.g., protective) assessment of room concentrations. While concentrations did not exceed occupational exposure limits from OSHA or ACGIH for individual contaminants, recommended agricultural health limits from exposure-response studies suggested in the literature were exceeded for respirable dust, CO₂, and NH₃, indicating a need to consider personal exposures and control options to reduce contaminant concentrations in farrowing rooms. Pit fans reduced NH₃ and H₂S concentrations, but these fans may not be sufficient to control dust and eliminate the need for secondary exposure prevention methods.

Keywords:

• concentration mapping
• farrowing barn
• gaseous contaminants
• respirable dust
• swine
• ventilation

ACKNOWLEDGMENTS

This research was funded by CDC/NIOSH Education and Research Center Training Grant T42OH008491, and the CDC/NIOSH Great Plains Center for Agricultural Health, U50 OH007548.

[Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplementary resources: mean exposure data, by test day, and data tables for statistical analyses discussed in the article.]