(CNN)Air pollution from food production in the United States is linked to an estimated 15,900 premature deaths each year, according to a new study published Monday in the Proceedings of National Academy of Sciences of the United States of America.
Air pollution from animal-based food production is linked to 12,700 deaths each year, study says
Of those, an estimated 12,700 deaths -- around 80% -- are connected to production of animal-based foods.
Scientists have known for years that farming contributes to harmful air pollution, but experts say this study offers the first full accounting of deaths connected to the production of certain types of food.
"When we think of the big sources of air pollution in the U.S., our imagination usually turns to smokestacks and tailpipes," said Joshua Apte, an assistant professor at the University of California-Berkeley, who was not involved in this study. "But it turns out that agriculture is also a major contributor to our air pollution and therefore we should care about it for our health."
The study focused on a specific type of tiny pollution particles known as PM2.5.
They linger in the air we breathe and measure barely a fraction of the diameter of a human hair. But despite their small size, the particles have been linked to millions of premature deaths globally, as well as serious cardiovascular and respiratory problems, especially in children and the elderly.
PM2.5 particles kicked up into the air by tilling and fuel combustion in farm equipment are part of the problem, but the study found the majority of premature deaths are linked to ammonia emissions from livestock waste and fertilizer. Airborne ammonia reacts with other chemicals to form dangerous particulate matter.
"(It happens) mostly through ammonia, which is released when farmers use nitrogen fertilizer -- which they use a lot of -- or is released from animal manure," said Jason Hill, a professor at the University of MInnesota and a co-author of the study.
The premature deaths connected to pollution from agriculture are heavily concentrated in California, Pennsylvania, North Carolina, and along the Upper Midwest's Corn Belt, the study found.
The researchers identified ways that both consumers and farmers can help reduce this type of pollution.
Eating less red meat and shifting toward plant-based diets could have huge health benefits, the study shows.
The study found that substituting poultry for red meat could prevent roughly 6,300 of the annual deaths tied to farming air pollution, and even larger reductions of 10,700 to 13,100 deaths could be achieved each year with large-scale shifts toward vegetarian, vegan, or flexitarian diets.
"It's probably healthy for them (to switch) and healthy for other people, because other people are not breathing polluted air," said Julian Marshall, another co-author of the study and a professor of environmental engineering at the University of Washington.
The study points to a few ways for farmers to cut down on the production of ammonia. Using fertilizer more precisely in order to maximize crop production can help. Farmers can also reduce the amount of ammonia produced from manure by covering animal waste and injecting manure into fields instead of spraying it.
Ian Faloona, an associate professor at the University of California-Davis, who published a study in 2018 on agriculture's production of nitrogen oxides -- another type of air pollution -- said that making these changes can also be good for farmers' bottom lines.
"In the end, it's going to be cost effective because you're making the process more efficient," Faloona said.
A spokesperson from the American Farm Bureau Federation questioned the study's results.
"On first review, it seems filled with data gaps and giant leaps to stretch the definition of cause and effect," the spokesperson said. "US agriculture is continually doing more using fewer natural resources and we're proud of that progress."
Hill said that he hopes that the report will show consumers and farmers alike that there are ways to reduce this problem.
"That's the message of hope here -- that we can actually do something about this," Hill said.