Odor Emissions from Typical Animal Production Farms in Ohio


Odor emissions from animal feeding operations (AFOs) remain a significant nuisance issue. Some neighboring communities of AFOs have complained that odor degraded their quality of life and well-being. Odor is a subjective response of humans, and the perception of odor varies significantly among people. Farmers may have been used to the farm smells and do not feel odor offensive. However, people with no farming background may be sensitive to odor and experience many different physiological and psychological responses to odor.

Unbiased scientific assessments are needed to resolve conflicts among farmers and neighboring communities and make objective and informed decisions about best management practices for odor mitigation in animal productions. Due to the complication and high cost of odor measurement, limited odor data are available to facilitate scientific understanding and develop effective mitigation of the odor concerns. The presentation reports on-farm odor sampling methods, measurement of odor concentrations in labs, and estimation of odor emission rates (ERs) for representative animal production farms in Ohio.

What Did We Do

Over the past decades, we have developed many research and extension projects to evaluate air quality and emissions at typical Ohio farms through seasonal on-farm sampling and monitoring measurement. The farms include swine, dairy, and poultry layer farms. Odorous air was sampled into 10-L Tedlar bags using a SKC-Vac-U-Chamber (SKC Inc., 863 Valley View Road, Eighty-Four PA 15330). The odor samples were shipped to the odor lab at Purdue University within 30 h of collection for measurement of odor concentrations (OUE m-3) using a dynamic olfactometer (AC’SCENT International Olfactometer, St. Croix Sensory, Inc., Stillwater, MN, USA).

When it was feasible to measure ventilation rates of animal facilities, the ventilation rate data along with the odor concentration data were used to estimate odor emission rate from the animal facilities. Further, the odor concentration and emission data were analyzed to identify correlation with environmental conditions and other air pollutant emissions, such as ammonia emission, to seek effective management practices for odor control.

What Have We Learned

Odor sources are animals and their manure and therefore can be physically associated with animal buildings, manure storages, and fields of manure land application. Different animal operations result in significantly different odor levels and liquid manure management practices are associated with higher odor levels.

The odor characteristics of layer house exhaust air were strongly associated with layer manure characteristics. The annual mean odor concentration was quantified as 355 ± 112 OUE m-3, and the annual mean odor emission rate was estimated as 0.14 ± 0.11 OUE s-1 hen-1for two manure-belt layer houses in Midwest region.

Significant seasonal variations were observed in odor concentrations inside the layer houses with high concentrations in summer and winter. The odor emission rates were the lowest in spring, but not significantly different in summer, fall, and winter.

House ventilation rate significantly affected odor emission rates, with higher ventilation rates corresponding to higher odor emissions. Ammonia concentration and emission rate inside the layer houses were significantly and positively correlated with the odor concentrations and emission rate.

Odor concentrations decrease exponentially as distances from the sources increase. Odor dispersion is affected by many factors. The data analysis also indicated seasonal and spatial variations in odor levels on farms, and the times and places that effective mitigation is needed. Measurements of odor are fundamentally important to understand odor concerns, develop estimation tools and effective mitigation.

Future Plans

Continue to develop odor mitigation management practices and technologies and tools to predict odor emission and dispersion from animal feeding operations.


Lingying Zhao, Professor and Extension Specialist, The Ohio State University

Additional Authors

-Glen Arnold, Assoc. Professor and Extension Field Specialist, The Ohio State University
-Mike Brugger, Faculty Emeritus, The Ohio State University
-Roger Bender, Former OSU Extension Educators. The Ohio State University
-Gene McClure, Former OSU Extension Educators. The Ohio State University
-Eric Immerman, Former OSU Extension Educators. The Ohio State University
-Albert Heber, Professor Emeritus, Purdue University
-JiQin, Ni, Professor, Purdue University

Additional Information


Zhao, L.Y., L.J. Hadlocon, R. B. Manuzon, M. J. Darr, X. Tong, A.J. Heber, and J.Q. Ni. 2015. Odour concentrations and emissions at two manure-belt egg layer houses in the U.S. J.Q. Ni, T.T. Lim, C. Wang (Eds.). In Animal Environment and Welfare–Proceedings of International Symposium (pp 42-49). Rong Chang, China, October 23-26th.


The air quality survey studies on Ohio farms were supported by the internal SEED grants of the Ohio Agricultural Research and Development Center, College of Food, Agricultural and Environmental Sciences, The Ohio State University.

The poultry layer house study was supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2005-35112-15422.

Appreciation is also expressed to the participating producers and staff for their collaboration and support.


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