Date Full Report Received


Date Abstract Report Received



Primary Investigator:

The goal of this project was to build credibility in rural communities for using the Odor Footprint Tool (OFT) as a planning and screening tool when siting swine facilities. The project had three objectives:
1) Involve a pork production operation, neighboring residents, and unbiased outside participants in an odor-monitoring study;
2) Pilot test the Odor Footprint Tool within a rural community for a proposed pork production facility; and
3) Install a biofilter on a pork production facility to demonstrate this technology and the potential for reducing odor impacts on rural communities.

Objective #1: Odor-Monitoring Study:
In the odor-monitoring study, 16 people were trained to assess odors using state-of-the-art field methods. Participants were trained to assess odor intensity, concentration, offensiveness, and character. Participants also provided a rating of the odor‟s „annoyance potential‟ by specifying whether the odor was „not annoying‟ or either “slightly”, “moderately”, “highly” or “extremely annoying”. This subjective rating was to encompass how the state of odor would affect their behavior (i.e. any change in activity) and how long the event would be remembered (e.g. hours vs. months). This information was collected to help qualify prediction of odor annoyance and to obtain a more direct linkage between odor levels and likely consequences of odor events. Moderately, highly, and extremely annoying states of odor were collectively referred to as “consequentially annoying”. The trained participants monitored odors around a 4,800-head finishing site in eastern Nebraska during 2005 and 2006. For six consecutive Tuesday evenings during the summer of 2005, 5-7 participants from Lincoln traveled to the area to monitor odor levels at locations downwind of the selected site, both before and after dark. During late spring and summer of 2006, 2 participants from another rural community in the local county monitored odor levels at downwind locations 2-5 times a week. During that same time period, 7 people who owned residences within 1.5 miles of the selected site also monitored odors. Five of these individuals monitored for odor 3 times a day – once each during daylight, twilight and nighttime conditions – just outside their residence. Additional sources of livestock odor were limited mainly to two other swine facilities that were at least ¾ of a mile away, so the source of detected odor could generally be determined based upon wind direction.

Based upon data reported by the individuals who were hired and trained to monitor odors within the downwind odor plume, the state of odor at off-site locations (1/8 mile or further from the facilities) was reported to be consequentially annoying in 20 out of 192 assessments. When on-site data was included, the rate rose to 53 consequentially annoying ratings out of 231 total assessments. This information shows that while odor levels immediately around the swine facility were very likely to be considered annoying (33 of 39 instances); most of the time, the odors were quickly dispersed and diluted to levels not normally considered to be consequential. When atmospheric conditions kept emitted exhaust air near the ground, however, odor  concentrations diminished much more slowly and the potential for negative odor effects extended greater distances downwind.

Modeling of each these assessment periods predicted that there were 18 consequentially annoying events at off-site locations. The 90% net prediction rate (18 predicted vs. 20 reported) for consequential annoyance was considered very promising given the nature of what is involved (odor, weather phenomena, and human assessments). Some steps for fine-tuning the predictive capabilities are being investigated to address the slight under-prediction of annoying odor levels and to minimize error rates. Five residents regularly monitored for odors outside their residences and made a total of 1,007 assessments. This large number of observations covering a broad spectrum of weather conditions was desired to test the general accuracy of the Odor Footprint Tool‟s prediction of „odor annoyance-free frequency‟. „Swine related odor‟ was detected during 92 of the observations or 9.1% of the total, with a range of 0-14.0% among residents. On 42 of these odor events, or 4.2% of the total assessments, residents indicated that the states of odor were annoying. An annoyance frequency of 4.2% equates to a 95.8% odor annoyance-free status overall. Given the locations of the residences with respect to the three swine production facilities in the area, predicted individual odor annoyance-free frequencies using the Odor Footprint Tool ranged from 90 to 99%. Annoyance frequencies for individual residents ranged from 0 to 11.4% and showed considerable variation due to individual biases (some residents were for and some against having the swine facilities in the area), senses of smell, data collection times, etc. On the whole, the composite annoyance free frequency based upon information supplied by area residents was comfortably within the predicted range, especially given that resident annoyance did not have to qualify as being „consequential‟.

Objective #2: Pilot-test of Odor Footprint Tool:
In March of 2005, a producer looking to construct a 2,400-head swine finishing facility in southern Madison County, NE, and the local planning and zoning commissioner agreed to utilize the Odor Footprint Tool during the application approval process. Odor footprints were developed and superimposed to scale on aerial photographs of the proposed site, showing the location of neighboring residences and the extent of the odor annoyance-free frequency curves. A 94% odor annoyance-free frequency was used to align with the tolerance level likely to be proposed for odor annoyance in agricultural areas of the county.

On June 16, 2005, these Odor Footprint Tool resources were included in the review of the pork producer‟s application. The following week, the odor footprint illustrating the extent of odor impact at 94% odor annoyance-free frequency was shown at a public hearing regarding the proposed facility. On July 28, 2005, the planning and zoning commissioners approved the application. At an October 2005 meeting of the Madison County Commissioners, the application was denied approval. While there was no way to know the real reasons for the differing decisions, much less time was allowed for explaining and illustrating the Odor Footprint Tool information to the county commissioners and meeting attendees.

Objective #3: Install a functional biofilter
After investigating a number of unfruitful leads with prospective pork producer cooperators, a site for installing a demonstration biofilter was found in the latter half of 2006. Design of the facility and the biofilter occurred during late 2006 and into 2007. Construction is set to begin during the summer of 2007 with demonstration of the biofilter to follow. A positive of the delay was that funds were received from the Nebraska Environmental Trust during 2006 that will more than double the biofilter expenses that we are able to cost-share.

Implications for the industry:
The odor-monitoring field study showed good agreement between odor dispersion model projections of the presence of annoying odor levels and human observations. This adds support for using tools like the Odor Footprint Tool to project out minimum separation distances between proposed swine buildings and residences.

Pilot testing the Odor Footprint Tool set a precedent in Nebraska that this tool has a place in the local decision-making process, at least from an informational standpoint. Inclusion of  science-based information at public meetings impacts discussion, and county officials have been receptive to learning more about the Odor Footprint Tool. At least three counties are pursuing options for incorporating the Odor Footprint Tool into local zoning ordinances. Sustaining growth in animal production and vibrant rural communities will likely depend on a combination of sound evaluation of the expected odor impacts of operations on surrounding areas and utilization of effective odor control – such as biofilters – where needed.

Contact information:

Rick Stowell, Extension Specialist – Animal Environment

University of Nebraska, (402) 472-3912, rstowell2@unl.edu