For many of the foodborne outbreaks of E. coli O157:H7 associated with leafy greens, the biological or environmental source of the bacterial contamination was not definitively determined. This ambiguity regarding the underlying source(s) of bacterial contamination has led to a wide range of food safety recommendations and guidance documents in an effort to reduce the risk of pathogen contamination either in the produce field, during harvest and transport, or during processing. A good example is the specific distances regarding proximity of a CAFO to a leafy green production field.

• To assess the safe set back distance between CAFOs and produce farms by examining airborne bacterial pathogens and indicator E. coli in proximity to beef cattle feedlots in Imperial Valley, California
• A pilot study in Imperial Valley to explore the concentration of airborne indicator E. coli.