This is not a peer-reviewed article. International Symposium on Air Quality and Waste Management for Agriculture. CD-Rom Proceedings of the 16-19 September 2007 Conference (Broomfield, Colorado) Publication date 16, September 2007 ASABE Publication Number 701P0907cd Quantification of Ambient p-Cresol Concentrations Downwind of Beef Cattle Feedyards Z.L. Perschbacher-Buser, D.B. Parker, K. Casey, G. Green, E. Caraway, and M. B. Rhoades ABSTRACT Livestock operations have become more concentrated in the Texas Panhandle, amplifying the need to manage odor and other nuisances while maintaining operational capabilities. As the cattle feeding industry sustains many small communities in the Texas Panhandle economically, it is imperative we develop greater understanding of odors and odor transport from beef cattle feedyards. Ambient concentrations of p-cresol, a significant odor component, was measured downwind of two beef cattle feedyards using thermal desorption tubes and gas chromatography- mass spectrometry (GC-MS). Downwind chemical concentrations of p-cresol were highest at the property line, but were drastically lower at the 0.8 km (0.5 mi) sampling locations and below most published odor thresholds at 2.4 km (1.5 miles). A sample obtained during stable atmospheric conditions 13 km (8 miles) downwind of a feedyard following a rain event had a noticeable odor and an elevated p-cresol concentration. Keywords. Odors, Volatile Organic Compounds (VOCs), p-cresol, beef cattle feedyards, concentrated animal feeding operations (CAFOs), INTRODUCTION The cattle feeding industry is an important contributor to many small communities in the Texas Panhandle whose local economies depend on the people they employ as well as those they serve. This region is the largest cattle-feeding region in the US and markets over 7 million head of fed cattle annually, accounting for approximately 30% of the nation’s fed beef (TCFA, 2005). Concentrated animal feeding operations (CAFOs) have become more concentrated in the Texas Panhandle. As a result of increased urban sprawl, these entities are now facing greater challenges with respect to odor and other nuisances. CAFOs are associated with odors which may be considered a nuisance by some downwind neighbors (Heber et al., 1999). Redwine and Lacey (2000) defined “nuisance” as an interference with the normal use and enjoyment of property. Odor impact and associated nuisance complaints depend on odor production at the facility, odor transport between that facility and its neighbors, weather, topography, and odor tolerance of their neighbors (Heber, 1997a; Lim et al., 2000; Guo et al., 2004). Separation distances or setbacks with regard to CAFOs are defined as the distance between a feeding operation or potential odor source and neighboring residences or public areas (Kohl et al., 1997; Redwine and Lacey, 2000). Setbacks have been used in the past by swine facilities to prevent nuisance complaints and lawsuits (Heber et al., 1999; Piringer et al., 1999). Odor qualities affecting neighbors include intensity, duration, and frequency of odor events (Heber, 1997b; Redwine and Lacey, 2000). Miller and Varel (2001) considered temperature, soil moisture, and manure composition the primary factors controlling anaerobic decomposition in feedyard soils and responsible for supplying odorous compounds. In their study, livestock odors were considered the result of volatile organic compounds (VOCs), defined as a mixture of carbon-, sulfur-, and nitrogen-containing compounds produced during incomplete anaerobic fermentation of manure. Volatile fatty acids (VFAs), alcohols, and aromatic ring compounds (phenols, indoles, and benzoates) were included as components of VOC emissions (Miller and Varel, 2001).