U.S. counties with hog and cattle feeding operations may be subject to higher air pollution levels, while lacking the health insurance necessary to treat related medical problems, a new study has found. 

Concentrations of an airborne contaminant linked to heart and respiratory issues were much greater near these feeding sites than in counties without them, scientists observed in the study, published on Tuesday in Communications Earth & Environment.

The researchers also observed that these sites were more likely to be located near vulnerable and marginalized communities — many of which had limited health insurance coverage and lower education levels.

To draw these conclusions, the researchers assessed nationwide concentrations of fine particulate matter (PM 2.5) around animal feeding operations (AFOs) — as opposed to including such emissions from agriculture or livestock production more broadly.

They narrowed their interests to home in on pollution near two categories of AFOs: cattle feedlots producing beef or dairy and hog farms producing pigs.

Based on the analyses, the scientists found that the country’s AFOs occupy an area equivalent to about 500,000 football fields, with cattle operations responsible for about 80 percent of that total.

The scientists used remote sensing tools to develop what they identified as the largest-ever spatial dataset for AFOs, with the precise locations and sizes of 15,726 cattle lots and hog farms.

They then used geo-statistical models to find connections between these facilities and PM 2.5 pollution levels, while creating socio-demographic profiles of affected communities.

The researchers identified and digitized 8,763 cattle AFOs in the contiguous U.S., with the majority located in the Midwest and West.

At the more local level, they found that just 21 counties have more than 50 cattle AFOs, collectively housing 26 percent of such facilities and 23 percent of these types of cattle.

Six counties in California’s Central Valley alone hosted half of these operations, according to the study.

Meanwhile, the researchers identified 6,963 hog farms across the contiguous U.S., with most of these concentrated in the Midwest, followed by the South.

Just 28 counties contained more than 50 hog production sites — hosting 41 percent of all such facilities and 28 percent of total hog farm areas, per the study.

Ultimately, the scientists determined that AFOs raise local PM 2.5 concentrations by 28 percent near cattle operations and 11 percent near hog farms, even after accounting for industrial and urban influences.

“It lingers in the air and can get really deep into your lungs and create scar tissue,” senior author Benjamin Goldstein, an assistant professor at the University of Michigan’s School for Environment and Sustainability, said in a statement, referring to PM 2.5. 

“It’s nasty stuff,” Goldstein added. “There are really no safe levels of it.”

The researchers also identified statistically robust, nationwide “evidence of livestock-induced air pollution,” noting that “socially vulnerable and minority populations — often with limited health insurance — are disproportionately affected.”

Senior author Joshua Newell, a professor at the School for Environment and Sustainability, stressed that by harnessing this mapping data, regulators could focus efforts to address health impacts on a limited number of counties.

“If you’re a policymaker, or a government or a community group or association concerned with these issues, this allows you to develop very targeted policies or measures,” Newell said in a statement.

Newell and his colleagues expressed hope that their research would help advance three policy objectives: to support Clean Air Act regulations for livestock operations, to identify vulnerable populations suffering undue pollution burdens and to pinpoint priority counties for pollution reduction measures.

They also stressed that livestock producers can be proactive about reducing PM 2.5 emissions, by using sprinklers to keep manure and soil wet — even in a piecemeal fashion.

“Livestock farms play a vital role in the economies of many rural communities and are expected to continue doing so for the foreseeable future,” the authors concluded, noting the contribution of such operations to environmental justice issues.

“These challenges are widespread and impact millions of Americans nationwide,” they added.