Official State of Iowa Website Here is how you know

Animal Feeding Operations

Hog, cattle, and turkey feeding operations


In 2002, the Iowa Legislature directed the DNR to perform a field study to determine airborne levels of ammonia, hydrogen sulfide, and odor near animal feeding operations.

The Iowa DNR has established a health based standard for hydrogen sulfide to compare against monitoring data to determine if levels pose a risk to public health. If levels measured at separated locations such as homes, public areas, schools, or religious buildings pose health risks, the DNR may develop plans and programs to reduce emissions at animal feeding operations.

The Iowa DNR convened workgroups on best management practices, air emissions characterization, and dispersion modeling as part of a continuing effort to develop a working understanding of the technical issues involved in air quality concerns associated with AFOs. Findings and recommendations of the workgroups have been compiled into a report.

The DNR has completed its field study of odor, hydrogen sulfide and ammonia concentrations near large animal feeding operations. The links below contain the final results of the study and supplemental information.

Odor Study Results and Resources

Additional Information

Hydrogen Sulfide and Ammonia Results and Resources

Executive Summary
Full Report
Site Results
Additional Information


The Iowa DNR Animal Feeding Operations Technical Workgroup, comprised of organizations with working knowledge of agricultural practices and technical expertise, has issued its final report. The report includes current technologies that are available now to producers to reduce air emissions from livestock operations. Adoption of these "best management practices" by producers will benefit the air quality on the farms themselves, at nearby residences, and overall environment by reducing air emissions. In addition, the report includes recommendations on the characterization of air emissions from animal feeding operations and dispersion model that can be used to estimate the concentrations of pollutants near animal feeding operations.