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As dairy operations evolve towards larger, concentrated facilities, air quality on and around the diary farms becomes a big concern. Data on air quality in and around large dairy facilities are insufficient and very much needed.

In this study, methodology and protocols to measure air quality on large dairy farms and to assess farmers and neighbors exposure to aerial pollutants were developed. Preliminary data on air quality spatial and temporal distributions on large diary farms were collected.

Measurements were made on two large diary farms with naturally ventilated free stall barns and outside manure storage. These are typical new dairy operations in Ohio. 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 and upwind and downwind locations. Dust was measured using a portable dust mass concentration meter. Gas and dust levels inside the dairy buildings at one leeward location were continuously monitored for four days in each season. 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 manure storage ponds has the most affect on air quality during warm and hot seasons. Variation of air quality inside the dairy building is small. Inside, the average dust mass concentrations range from 0.9 to 1.5 mg/m3 and ammonia concentrations range from 1.4 to 3 ppm in different seasons. Odor concentration inside the dairy building were in the range of 90 to 140 OU/m3, but near the manure storage ponds, it reached as high as 1256 OU/m3 during the hot weather measurements. Weather conditions affected the outdoor dispersion of air emissions. At 500 feet from the barn and manure storage, gas levels were similar to upwind levels. The odor levels at 500 ft downwind of the farms were high enough to raise concerns on hot and windy days.

Inside the building, the hydrogen sulfide concentration were not significant different from hour to hour in a day and from day to day in a season. Hourly variations of dust concentration were not significantly different during day time. Daily variation of mean ammonia concentrations were significantly different, but hourly mean ammonia concentrations were not significantly different among morning hours and afternoon hours of a day.