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There are 15,000 cattle and hog feeding operations in the United States, rearing 70% of the country’s cattle and 98% of hogs. Thanks to new research from the University of Michigan School for Environment and Sustainability (SEAS), we now know where most of them are. The team of researchers found that a quarter of the nation’s hog and cattle feeding operations are found in just 30 counties out of more than 3,000 in the United States. They also found that an air pollutant linked to heart and respiratory issues near these animal feeding operations (AFOs) was higher than in similar counties with no feeding operations. The study also revealed that there was a higher likelihood of finding vulnerable and marginalized communities near AFOs. 

“One of the things that this study reveals is that we could focus on a limited number of counties to really address health impacts in these communities,” said Joshua Newell, a senior author of the report published in Communications Earth & Environment.

The lead author of the study is SEAS alum Sanaz Chamanara (MLA '17, PhD '22). Benjamin Goldstein, assistant professor at SEAS, is senior author, and Dimitris Gounaridis, assistant research scientist with SEAS, is a co-author.

Read the full press release on the Michigan News website.

Study: Animal feeding operations are associated with heightened concentrations of fine particulate matter and affect vulnerable communities in the United States (DOI: 10.1038/s43247-025-02520-w)