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Abstract. Many livestock confinement facilities, particularly swine, are built to incorporate long term manure storage beneath slotted floors. Manure storage structures needing final cleanout or maintenance must be ventilated to remove any noxious gas prior to human entry, often employing positive-pressure pit-safety fans. Prior research has only considered safety ventilation of stand-alone manure pits. It is important to consider the effects of pit-safety ventilation on the animal living space above manure pits with slotted covers. Computational fluid dynamics (CFD) allows engineers to evaluate alternate pit-safety fan locations without performing costly field trials, but CFD models must be validated by comparing simulated results to measured data to ensure the model accurately represents physical reality. This research was performed to develop a CFD model of a swine nursery room located above a manure pit with a fully-slotted cover and to validate that model using measured data from a physical experiment. Hydrogen sulfide (H₂S) gas decay was measured at several locations inside a swine nursery room during combined manure pit and room ventilation using fifteen personal gas monitors with electrochemical sensors and built-in dataloggers. Once the CFD model of the nursery room was developed, transient simulations of pit-safety and room ventilation were performed. Simulation results were compared to average measured gas concentrations from four replications at 15 measurement locations in the nursery room. Results indicated that the simulated temporal gas concentrations at 8 of 15 locations agreed favorably with measured values (regression slope between 0.75 and 1.25, R² > 0.80, intercept < 27%, and > 50% of simulated values within ± 2 S.D. of average measured values) after adjusting simulated values for a first-order instrument response. These results indicated that CFD is suitable for predicting H₂S gas distribution in the animal living space above manure storages during pit-safety ventilation events.