Variations in air quality of new Ohio dairy facilities with natural ventilation systems

As dairy operations evolve towards larger, concentrated facilities, air quality on and around the dairy farms becomes a concern. Data on air quality in and around large dairy facilities are insufficient and therefore very much needed. In this study, preliminary data on air quality spatial distribution and temporal variations on two new large dairy facilities with naturally ventilated free stall barns and outside manure storage were collected. Concentration of hydrogen sulfide (H2S) and ammonia (NH3) at 12 to 14 locations on each farm were measured in three seasons using portable gas analyzers. Odor samples were collected at odor sources, upwind and downwind locations. Dust was measured using a portable dust mass concentration meter Gas levels inside the dairy buildings at one leeward location were continuously monitored for three days in two seasons. In addition, indoor and outdoor temperature, relative humidity, and air velocity were measured to determine effects of these parameters on air quality. The study found that manure storage ponds have the most effect on air quality during warm and hot seasons. Variations of air quality inside the dairy building were insignificant. Inside the dairy buildings, the average dust mass concentrations range from 0.9 to 1.5 mg m(-3); ammonia 1.4 to 3 ppm, hydrogen sulfide 2 to 32 ppb; and odor concentration 90 to 140 OU m(-3). However at the downwind berm of the manure storage ponds, odor concentration reached 1256 OU/m(3) during the hot weather months. Weather conditions also affected the outdoor dispersion of air emissions. Most of the time, gas levels at 152 m downwind of the barn and manure storage were similar to upwind levels, but on hot and windy days these levels reached a point high enough to raise concerns. Inside the building, the hydrogen sulfide concentrations were not significantly different from hour to hour within a day or from day to day within a season. Although daily variation of mean ammonia concentrations were significantly different, hourly mean ammonia concentrations were not significantly different between morning hours and afternoon hours within any given day