As the controversies between pork producers and their neighbors grow, Iowa State University and the University of Iowa have released a report to help the Iowa Department of Natural Resources (DNR) develop guidelines for measuring and regulating air emissions from confined animal feeding operations (CAFOs).

In June 2001, Iowa Gov. Tom Vilsack asked the presidents of both universities to make peer-reviewed, science-based recommendations together. The final report, “Iowa Concentrated Animal Feeding Operations Air Quality Study,” includes the study group's answers to five direct questions, supported by 10 chapters of analyses of existing research.

The questions and answers in the executive summary addressed:

  • Whether direct evidence of harm to humans by CAFO emissions was available;

  • Which odorous compounds should be regulated and at what levels (specifically hydrogen sulfide and ammonia);

  • Suggested actions to address the emerging CAFO issues; and

  • Recommendations for methods of reducing or minimizing emissions from CAFOs.

“The study came about because the issue continues to grow due to concerned citizens,” explains study group member Kelley Donham, professor in the Department of Occupational and Environmental Health at the University of Iowa College of Public Health. “The DNR has people demanding that they do sampling.”

The group, including 14 Iowa State scientists and 13 University of Iowa researchers, first met in December 2001 to establish protocols and divide the study responsibilities based on individual's specialty areas.

“Several authors worked together on each chapter of the report,” Donham says. “I think more than 5,000 hours from both schools went into this report.”

The 221-page report, released in February, created some controversy among university personnel and producer groups.

“The executive summary is really a consensus piece,” Donham says. “The individual chapters are not really consensus of the whole group, only of the authors [of individual chapters].”

Others disagree. The report is a majority report, but not unanimous as some people are asserting, explains a committee member requesting anonymity. Also, the executive summary was actually written by three administrators and one scientist from each university because the scientists from the two universities could not come to agreement. The administrative team made the decisions on the final wording of the executive summary.

While all committee members were advised of the preliminary versions of the executive summary, some of the study group members did not see the final executive summary until after it was published, explains one source.

Because the lack of consensus is reinforced by differing opinions on how to regulate odors, the report includes two separate odor regulation approaches.

The first approach recommends that odor be measured at a residence or public use area. Odor level should not exceed 7:1 dilutions in two measurements separated by four hours on any given day. The dilutions should not exceed 15:1 at the property line. This option also allows CAFOs 14 days during a calendar year (with 48-hour notice) to exceed those odor limits at the property line. If CAFOs exceed those limits, then regulatory action should be taken, according to the study's executive summary.

The second approach states, “Odor recommendations are more difficult to establish because studies relating health impacts to odor exposure have not measured odor concentrations.” This option recommends sampling odors at the source and the residence or public-use area to measure the frequency, duration and concentration of exposure to odor. These scientists recommended using the available modeling tools, instead of excessive monitoring.

Some study group members say funding is needed for additional random studies on air emissions from animal operations. Donham disagrees: “We felt we had the evidence to make these recommendations without waiting at least two years for additional research and without being a burden to the industry.”

However, Iowa DNR Director Jeffrey Vonk has put forth a plan that would monitor emissions for a period of time prior to setting regulatory numbers. This suggests that the government agencies agreed that additional studies were necessary.

The study group was led by Richard Ross, distinguished professor in the Department of Veterinary Medicine and former dean of the College of Agriculture at ISU, and James Merchant, dean and professor of the College of Public Health at the University of Iowa.

The recommendations were considered as the Iowa Legislature developed new livestock regulations during its 2002 session (see related story, page 46). The legislation, which requires the Iowa governor's signature before becoming law, allows the DNR to make rules limiting air emissions from permitted facilities. The law would impose user fees on producers to fund additional DNR staff and equipment to monitor facilities.

The complete report is available on the Internet in PDF format at