butions of AFO emissions to potential effects and the subsequent implementation of control measures. USDA and EPA should first focus their efforts on measurement and control of those emissions of major concern.
Measurement protocols, control strategies and management techniques must be emission and scale specific (Finding 3, pp. 5, 71).
For air emissions important on a global or national scale (i.e., ammonia [NH3] and the greenhouse gases, methane [CH4], and nitrous oxide [N2O]), the aim is to control emissions per unit of production (kilogram of food produced) rather than emissions per farm. Where the environmental and health benefits outweigh the costs of mitigation it is important to decrease the aggregate emissions. In some geographic regions, aggregate emission goals may limit the number of animals produced in those regions.
For air emissions important on a local scale (hydrogen sulfide [H2S], particulate matter [PM], and odor), the aim is to control ambient concentrations at the farm boundary and/or nearest occupied dwelling. Standards applicable to the farm boundary and/or nearest occupied dwelling must be developed.
Monitoring should be conducted to measure concentrations of air pollutants with possible health concerns at times when they are likely to be highest and in places where the densities of animals and humans, and typical meteorological conditions, are likely to result in the highest degree of human exposure.
There is a general paucity of credible scientific information on the effects of mitigation technology on concentrations, rates, and fates of air emissions from AFOs. However, the implementation of technically and economically feasible management practices (e.g., manure incorporation into soil) designed to decrease emissions should not be delayed (Finding 4, pp. 6, 72).
RECOMMENDATION: Best management practices (BMPs) aimed at mitigating AFO air emissions should continue to be improved and applied as new information is developed on the character, amount, and dispersion of these air emissions, and on their health and environmental effects. A systems analysis should include impacts of a BMP on other parts of the entire system.