Hydrogen sulfide levels were measured in two mechanically ventilated 1,000 pig finsihing buildings. The study set out to measure seasonal variation in hydrogen sulfide levels and factors that impact these variations, evaluate daily hydrogen sulfide variation and distinguish different patterns and examine spatial hydrogen sulfide concentration levels at three sampling locations.

Average daily mean building concentrations in both facilities were 3180 +/- 16 ppb and 232 +/- 39 ppb, the difference between the mean concentration in the two buildings was not statistically significant. Seasonal concentration patterns were saddle-shaped, with lowest concentration levels reported in early June and highest concentrations in April and September. Hydroegn sulfide concnetration levels were inversely correlated to building ventilation rate, which varied according to seasonal temperatures. The highest daily mean hydrogen sulfide rate corresposnded to th day airflow rates were the lowest.

Daily hydorgen sulfide concentration rates are influenced by ambient temperature followed by the building ventilation variation. Four daily concentration patterns were identified, 92% of the time hydrogen sulfide concentrations varied indirectly with building airflow followed by the outside air temperature. Spatial variations were very evident throughout the study. Barn 3b had a range of 271 ppb between the end wall and pit chimney, while Barn 4B had a range of 265 ppb ebtween the end wall and pit head space. Therefore it is very important in determing the appropriate the proper location of measurement, that which will be determined by the objectives set out in the experiment.