Critique of EPA's draft broiler emissions models by Iowa state scientists

By Andi Anderson

A recent analysis by Iowa State University scientists points to the need for improvements in the U.S. Environmental Protection Agency's (EPA) draft models intended for emissions forecasting in broiler operations. Released in August, these models aim to estimate levels of ammonia, hydrogen sulfide, and particulate matter emitted from U.S. broiler houses.

The research, led by Associate Professor Brett Ramirez, critiques the models' reliance on data from 2005-2007, considering significant changes in the broiler industry since then. Ramirez highlights the models' complexity and infeasibility for smaller growers, alongside their potential inaccuracy.

Critically, the models were developed using data from just four facilities in Kentucky and California, states not representative of the largest broiler producers. This limited data scope raises concerns about the models' applicability across the diverse U.S. broiler industry.

The research team found inconsistencies in the models, such as predicting higher emissions from multiple smaller barns compared to a single larger one, despite housing the same number of birds. This contradicts the expectation that emissions should be relatively consistent per bird under similar environmental conditions.

The draft models lack information for adequately extrapolating to larger, more common facilities in the industry today. The team's evaluation, also involving researchers from the University of Georgia, the University of Nebraska-Lincoln, and the University of Tennessee, was published in the Journal of Applied Poultry Research.

Their findings suggest the EPA's current draft models may not accurately estimate emissions from various broiler operations, prompting the scientists to encourage stakeholders to review this information and respond during the EPA's comment period.

This research was supported by the U.S. Poultry and Egg Association and state and USDA Hatch Act funds, with the disclaimer that the findings represent the researchers' views and not those of the funding bodies. It emphasizes the importance of updating and refining these models to better reflect current broiler operations and ensure effective environmental regulation.

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