Chapter 4. Emissions and Community Exposures from CAFOs

This chapter is a review of research and peer-reviewed literature on the emission rates and emission models for dispersion of gases from CAFOs. Emissions originate from the housing ventilation air, manure storage units, and during land application of manure. Refereed publications were sought that identified ammonia, methane, hydrogen sulfide, particulate, bioaerosol, and volatile organic compound (VOCs, including “odor”) emission from swine, dairy/cattle, and poultry production systems. The vast majority of published data is related to ammonia emission, and where available, the remaining components were cited and reported. A lack of data exists that reports downwind concentration of gases and particulates from CAFOs as a function of facility type and emission rate. Dispersion models predict the relationship between concentrations at a receptor and emissions from a source. Appropriate dispersion models for use in predicting concentrations of compounds are reviewed, with reference to current and peer-reviewed literature reports. Dispersion models are generally found to poorly predict absolute concentrations, but are adequate for predicting trends and the expected relationship between reduced emissions and reduced downwind concentrations. A series of tables is provided at the end of this chapter summarizing the reported emission rates o