Minnesota/Wisconsin Engineering Notes

February 2004 Postharvest and Alternative Energy Info on Web Your Farm Doesn’t Have to Smell that Bad Science-based Information on Manure Management Issues Competitive Milking? Bedded Pack Housing For Dairy Cows Livestock Ventilation Design—Indoor and Outdoor Air Quality Concerns EDEN – Extension Disaster Education Network Workshops on Food System Terrorist Threats Irrigated Acres Update New Book and Companion CD Focus on Dairy Replacements Resources Calendar

Livestock Ventilation Design—Indoor and Outdoor Air Quality Concerns Larry D. Jacobson, Minnesota Extension Engineer For the past 50 years, designers of livestock ventilation systems have worried only about indoor environments. However, with the recent concerns over outdoor air quality, specifically odor near livestock and poultry operations, and potential regulatory thresholds of certain gas emissions from animal production sites, designers of livestock production and ventilation systems need to be concerned with the amount of ammonia, hydrogen sulfide, odor, and other pollutants that are being emitted from these buildings. As with other industrial sources, state and federal regulators are beginning to examine air emissions from animal production systems to see if they exceed Clean Air Act thresholds. The U.S. Environmental Protection Agency (EPA) typically limits hazardous air pollutants such as ammonia, hydrogen sulfide, and PM10 (particulate matter under 10 mm or 10-6 m in size) to 100 tons / year or 100 lbs / day. This means that designers of livestock and poultry operations may soon need to monitor the amounts of these pollutants being emitted into the atmosphere. In the past, if the indoor concentration of a certain gas or pollutant was too high, one could simply increase the ventilation rate since the atmosphere was viewed as an infinite sink for gas, dust, and odor pollutants. In the near future, this may not be the case. Besides the need to control indoor conditions for both human and animal health and productivity, the amount (mass) of certain compounds will also need to be controlled to meet air emissions standards. Table 1 lists the mean and standard deviations for continuous 2+ weeks measurements of ammonia from a recent study of two barn types in the winter and summer. The ammonia concentration values are similar for both barn types with nearly equal levels in the winter (8 to 9 ppm) and in the summer (5 to 6 ppm). These ammonia concentrations are within the range (less than 10 ppm) that many extension agricultural engineers recommend in pig housing units in the United States. However, when expressed as emissions on a per pig basis, values for the deep-bedded barn are roughly 10 times larger then for the slatted barn in both winter and summer. Thus, assuming the estimated emission rates are similar throughout the year and there were enough pigs to reach ammonia emission thresholds, you would need to either reduce the generation of ammonia inside the barn or capture and remove some ammonia as it was being exhausted.   Winter Summer Barn Type Conc. (SD) ppm Emissions (SD) mg/s/pig Conc.(SD) ppm Emissions (SD) mg/s/pig       Deep-bedded Hoop barn 9.3(5.0) 0.39 (0.20) 5.9 (6.0) 0.43 (0.45) Slatted floor barn 8.5 (3.1) 0.02 (0.006) 5.1 (2.9) 0.06 (0.06) Table 1. Mean and Standard Deviation of NH3 Concentrations and Emissions for a Deep-bedded Hoop finishing barn and for a slatted floor curtain-sided finishing barn.

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