Surveys in Pennsylvania paint a conflicting picture of the impact of living near hog units.

Sometimes it seems there is little rhyme or reason for public sentiment when it comes to pork production.

In Lancaster County, PA, the densest hog county in the state, pork producers face virtually no opposition in proposing or getting a permit for a hog building, reported Ken Kephart, professor of Animal Science at Pennsylvania State University (PSU), in an opening address at the University of Illinois Pork Industry Conference in Champaign, IL. The county's 2002 hog inventory of 339,300 compares to a human population of nearly 500,000.

Lancaster County's population surge has forced land prices higher and limited access to cropland for manure application. Hog expansion in the state has been pushed north to more rural counties (see map).

Tioga and Bradford counties, for example, have seen 6- to 10-fold increases in hog production in the last decade. The human population in those two counties is only 104,000.

Yet producers in Tioga and Bradford counties are facing growing levels of resistance to proposals and permits for hog operations, Kephart says.

Those contradictions in public opinion are hard to explain. But, he speculates that the residents in Lancaster County could just be more accustomed to hog farms because they virtually dominate the landscape, while homeowners in the other two counties are adjusting to change.

A survey of Lancaster County residents found that of those who did complain about neighboring hog farms, 57% objected to odors. About 72% of the participants in the 1998 study had direct family ties to agriculture.

Quality of Life Survey

Kephart reported on a 2002 PSU survey in Pennsylvania that provided some interesting perspectives about public views regarding hog farms. In the survey, eight neighbors were asked to rate the impact of local hog operations on the neighborhood quality of life. More than one-third of the 234 respondents frequently changed their outdoor plans because of odor from a local hog facility. More than 25% of respondents frequently complained about hog odors, and more than 18% often decided not to invite friends over because of odor. About 20% often wished they lived elsewhere (Table 1).

Table 1. Responses to Seven Statements Regarding the Impact of a Neighboring Swine Operation in Pennsylvania on Quality of Lifea
Neighbor Response (%)
Statement Never/Rarelyb Occasionally Often
I expressed concern to the operator of the facility about the odor coming from it. 82.9 13.0 4.2
I modified my outdoor plans because of the odors from this facility. 45.2 20.7 34.1
I decided not to invite friends to visit because of the odor from this facility. 64.1 17.5 18.4
The odor from this facility made me ill. 82.5 11.3 6.1
I complained to one or more neighbors or friends about the odor emanating from this facility. 49.8 22.6 27.6
I participated in a group or community meeting protesting the odor from this facility. 83.1 9.9 7.0
I've wished I didn't live in this location because of the swine facility. 63.4 16.0 20.7
aSurvey instrument contained the following wording: “Now consider how, if at all, the large-scale swine operation located near your home has impacted you and your lifestyle. Indicate how often you have experienced each of the following (statements) in the past year.” Adapted from Robert E. Mikesell's PhD dissertation in 2002 for “Odor Remediation and Siting Considerations for Pennsylvania Swine Farms,” published by The Pennsylvania State University.
bNever and rarely responses were combined.


Table 2. Comparative Frequency of Reported Health Symptoms Between Neighbors of One of Eight Swine Operations in Pennsylvania, and Non-Neighbors Living in Similar Rural Areasa
Neighbors (%) Non-Neighbors (%)
Symptom 0 - 5 Times > 6 Times 0 - 5 Times >6 Times
Cough 73.3 26.7 82.0 18.0
Nausea 79.5 20.5 93.9 6.1
Headache 48.3 51.7 59.8 40.2
Muscular aches 48.5 51.5 52.0 48.0
Chest tightness 83.1 16.9 89.8 10.2
Fatigue 49.3 50.7 64.0 36.0
Throat irritation 67.3 32.7 82.8 17.2
Depression 85.2 14.8 87.8 12.2
Anxiety 83.8 16.2 87.6 12.4
aSurvey instrument contained the following wording: “How often in the last year have you experienced each of the following symptoms?” Adapted from Robert E. Mikesell's PhD dissertation, 2002, “Odor Remediation and Siting Considerations for Pennsylvania Swine Farms,” at the Pennsylvania State University.


In the same study, neighbors were asked to record subjective scores on odors during evening hours. As expected, neighbors closer to, and downwind from, a hog operation recorded higher levels of objectionable odors.

But Kephart says personal factors also greatly affected perceived odor intensity, including:

  • The more the neighbor was acquainted with the hog farm manager/owner, the lower the reported odor levels;

  • The more “attractive” the hog farm was perceived to be, the lower the odor scores or complaints; and

  • As neighbors' self-evaluation of their health improved, odor scores improved.



Several personal factors had little or no impact on odor scores, explains Kephart. These included: income, gender, age, education, whether the neighbor had been raised on a farm, length of time the neighbor lived at a residence and the neighbor's reported knowledge of hog production.

When producers voluntarily agreed to postpone manure application and to learn the impact of buildings and manure storage on odor levels, many neighbors in the survey commented that odor levels were reduced.

“While the comments on manure spreading were unexpected, they do reinforce the concept that land application of manure may generate more odor complaints than the buildings or manure storage facilities,” says Kephart.

Respondents in the survey who were both neighbors and non-neighbors of hog farms had nearly identical self-health evaluation scores and disease symptoms when demographics were accounted for (Table 2).

Impact on Property Values

A 2003 study of Berks County, PA, by PSU agricultural economists, shows that locating large hog operations (inventory of more than 1,380 hogs) within 2,640 ft. of a rural residence reduces the property value of that residence by 4.1%, compared to a 6.9% reduction when located next to a landfill.

The average impact of a single animal production facility on 119 single-family residences within a mile of that facility is a 1.7% decline of the assessed value of those homes.

Illinois Survey

Ann Reisner of the University of Illinois, reported data on hog operations from 22 state newspapers in 52 counties, then compared it with beliefs of major stakeholders identified in the articles.

Nearly all of the newspaper articles were written about controversies before hog operations were built or expanded and were almost evenly divided between pro and con arguments.

Farmers with large-scale swine operations obviously believe in the value of their business to the community more than other rural residents, she says.

But a substantial minority of neighbors said they believe the swine industry provides a variety of economic impacts, and they largely agreed that farmers need to expand for economic reasons.

Avoiding Conflict

Pennsylvania State University's Ken Kephart offers four ways to stay out of odor-related legal trouble with your neighbors:

  1. Take every complaint, no matter how small, seriously.

  2. Document every complaint about your operation.

  3. Consider going to the neighbors right away to discuss problems. Sometimes this helps a lot and the complaint goes away.

  4. Keep your hog operation clean and attractive.



Manure, Odor Control Projects Outlined

Following are highlights of some of the research projects presented at the University of Illinois Pork Industry Conference:

  • Using phytase in hog rations could reduce phosphorus concentration in manure by up to 50%, cutting odor, according to studies led by David Baker, University of Illinois animal science professor emeritus.

    Phosphorus is organically bound as phytate, but in this form is largely unavailable to pigs because they lack phytase, the enzyme necessary to make the phosphorus available to them, notes Baker. Consequently, up to 75% of the phosphorus is excreted.

    Phytase was added to swine diets to enhance phosphorus utilization. “In one study, we found that by formulating early/late (180-260 lb.) finishing pig diets using genetically enhanced (low phytate) corn containing reduced amounts of indigestible phytate phosphorus and greater amounts of inorganic phosphorus, we can cut phosphorus excretion by up to 50%,” says Baker.

  • Raising the level of discharge of hog odors, such as with a smokestack, does not greatly reduce the level of odor, says Illinois State Water Survey scientist Allen Williams.

    But using a “nanonose” to measure nanometer-sized aerosol particles shows promise for routine odor measurement, he says. A nanometer is equal to one-billionth of a meter (3 ft.).

    While costs need to be reduced, a “nanonose,” once set up, could potentially analyze hundreds of odor samples in a day, compared to only a dozen or so with the current olfactometry method, says Williams.

  • An aerobic thermophilic system which research suggests is expected to remove more than 80% of hog odors, is being planned for construction on an Illinois hog farm, says James Blackburn, professor of mechanical engineering and energy processing, Southern Illinois University.

    The system utilizes aerobic biological oxidation at 131° F to reduce odors by 60-70% within six days.

  • Adding phytase to swine diets containing wheat middlings and no supplemental inorganic phosphorus produced performance equal to diets with inorganic phosphorus, reports Gary Apgar, Southern Illinois University.

    Removing inorganic phosphorus from grow-finish diets reduced average daily gain and feed intake, but adding phytase maintained pig performance.

    “Pig performance was not affected when diets with reduced nitrogen and sulfur were fed, provided amino acid level and balance were adequate, but odor-causing components were altered,” says Apgar.

  • Composting shows promise as a feasible method of manure disposal. Illinois producers have developed a brand-name compost available for value-added marketing.

    Solid and liquid manure can be composted by producers of all sizes, says Paul Walker, professor of animal science at Illinois State University.

  • Two types of lagoon covers were studied by Yuanhui Zhang, University of Illinois agricultural engineering professor.



A positive-pressure cover, inflated over a lagoon, reduced odor emissions, but proved difficult to construct and maintain.

“A negative-pressure cover, which is kept in contact with the slurry surface by drawing a continuous, low volume of air from beneath the cover, was effective at reducing emissions from the lagoon and was structurally sound,” says Zhang.

Zhang also tested three different types of devices for removing dust and odor from swine barns, including an aerodynamic de-duster. Trials produced a practical model for retrofitting hog barns. Further testing will be done to develop a unit that combines a high level of dust and ammonia removal.

Illinois Manure/Odor Research Initiative Completes Work

A total of 29 research projects were completed as part of the Council on Food and Agricultural Research (C-FAR)-Specific Research Initiative on Swine Odor and Waste Management, which concluded in 2003.

The five-year, $16-million project, led by University of Illinois animal scientist Michael Ellis, was supported by funding from C-FAR and a variety of other state agencies.

The projects were carried out by scientists at the University of Illinois, Illinois State University and Southern Illinois University.

Five areas were studied: measuring swine odors, characterizing odor emissions from swine facilities, storing and processing swine manure, nutrition issues and social and legal issues.