Disclaimer

Purdue University does not accept any responsibility for the outputs of the setback guideline. We expressly disclaim any responsibility for any damage arising from the application or reliance on the recommendations and information contained herein.  

Introduction

Odor control is a major concern of livestock producers in the United States. The use of atmospheric air to dilute odors from livestock facilities by appropriate setback distances is still the most popular and cost-effective strategy to reduce odor nuisance. However, the determination of odor-based setbacks for livestock facilities is a difficult and complex problem with only limited supporting data in the U.S.

A simple-to-use, site-specific setback guideline was developed by Purdue University for U.S. swine production systems in this project. The guideline considers facility size, orientation and shape, wind frequency, land use, topography, building design and management, manure handling characteristics, and odor abatement effectiveness. Odor emission factors were based in part on actual odor emission measurements in commercial buildings. Atmospheric dispersion models were also used to enhance and validate the setback guideline.

The interactive setback model on this page combines features of Austrian and British setback guidelines (Schauberger and Piringer, 1997; Williams and Thompson, 1985) (click on Austrian guideline to read about it) and incorporates new features developed in this research. The Purdue guideline is as follows:

Setback distance in feet = 20 F x L x T x V x (A_EE+A_S S)^0.5

where:
            F = wind frequency factor [0.75 to 1.00],
            L = land use factor [0.5 to 1.00],
            T = topography factor [0.8 to 1.00],
            V = orientation and shape factor [1.00 to 1.15],
            E = building odor emission, N x P x B, OU/s,
                    N = number of pigs,
                    P = odor emission factor, OU/s-pig, [1 to 15],
                    B = building design and management factor, M-D,
                            M = manure removal frequency [0.50 to 1.00],
                            D = manure dilution factor [0.00 to 0.20],
            S = odor emission from outdoor storage, C x G, OU/s,
                    C = odor emission factor for outside liquid manure storage, 50 OU/s-AU
                    G = animal unit, AU=1,100 lb of pig weight.
            A_E = odor abatement factor for buildings [0.30 to 1.00],
            A_S = odor abatement factor for outside liquid manure storage [0.30 to 1.00]

Williams, M.L. and N. Thompson. 1985. The effects of weather on odour dispersion from livestock buildings and from fields. In: Odor Prevention and Control or Organic Sludge and Livestock Farming. Ed: V.C. Nielsen, J.H. Voorburg, and P.L'Hermite. Elsevier Applied Science Publishers, New York. Pp. 227-233.