estimating air emissions are being left for that report as noted in relevant places in this interim report. The committee has answered the following sets of questions in the interim report within the confines of the Statement of Task (see Appendix A):

  • What are the scientific criteria needed to ensure that reasonably appropriate estimates of emissions are obtained? What are the strengths, weaknesses, and gaps of published methods to measure specific emissions and develop emission factors that are published in the scientific literature? How should the variability due to regional differences, daily and seasonal changes, animal life stage, and different management approaches be characterized? How should the statistical uncertainty in emissions measurements and emissions factors be characterized in the scientific literature?

  • Are the emission estimation approaches described in the EPA report Air Emissions from Animal Feeding Operations (EPA, 2001a) appropriate? If not, how should industry characteristics and emission mitigation techniques be characterized? Should model farms be used to represent the industry? If so, how? What substances should be characterized and how can inherent fluctuations be accounted for? What components of manure should be included in the estimation approaches (e.g., nitrogen, sulfur, volatile solids [see Appendix B])? What additional emission mitigation technologies and management practices should be considered?

  • What criteria, including capital costs, operating costs, and technical feasibility, are needed to develop and assess the effectiveness of emission mitigation techniques and best management practices?

Given the specific nature of the questions posed by EPA, the committee has not yet addressed some of the longer-term issues related to AFOs. To the extent possible, these will be addressed in the final report, which will build upon the findings of this interim report and include a more detailed response to the committee’s full Statement of Task (see Appendix A). The need for further discussion in the final report is indicated for some specific concerns in various places in this report. The topics to be covered in the final report fall in eight broad categories: (1) industry size and structure, (2) emission measurement methodology, (3) mitigation technology and best management plans, (4) short-and long-term research priorities, (5) model farm approaches, (6) human health and environmental impacts, (7) economic analyses, and (8) other potential air emissions of concern.

The quality of data for estimating air emissions from AFOs is an issue throughout this report. The committee’s inclination at first was to refer only to data from peer-reviewed sources. It soon became evident that this would eliminate a number of references that were prepared and relied upon by federal and state agencies, including the EPA (2001a) report that the committee is

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