(Reuters Health) - Air pollution from large-scale livestock farms impairs lung function in neighbors who live nearby, a new study from the Netherlands shows.

“It’s well known that air pollution causes lung problems, and usually we think about air pollution from industry, cars,” said senior author Lidwien Smit. “Until now, it’s been seen as an urban health problem but not so much as a big problem in rural areas,” he added.

“Our study shows that air pollution from livestock farms is causing lung function declines in areas where people live near farms,” Smit, an environmental epidemiologist and professor at Utrecht University in the Netherlands, said in a Skype interview.

She and her team measured several markers of lung function in 2,308 adults who lived in 12 villages near, but not on, farms in the Netherlands, which has one of the world’s highest population densities as well as one of the highest livestock farm densities.

The more livestock farms that were near participants’ homes - within 1,000 meters, or six-tenths of a mile - the more impairments researchers found in how participants expelled air when they exhaled.

The study also showed that neighboring residents’ lung function was reduced during weeks with higher levels of farm-related ammonia air pollution, Smit said. The effects on breathing patterns were small but significant, she said.

Prior studies have shown that livestock farms contain high levels of dust, which can lead to respiratory problems in farm workers, the authors write in the American Journal of Respiratory and Critical Care Medicine.

Livestock farms also emit ammonia, an irritant gas formed by enzymes in animal waste. When ammonia reacts with other gases, it forms fine dust particles, Smit said.

Dr. Daniel Jackson, a pediatrician and professor at University of Wisconsin School of Medicine and Public Health in Madison, said the study highlights how public policy can impact individual health.

“Decisions that can lead to worsening air quality can have very significant impacts on health,” said Jackson, who was not involved with the study.

“This paper highlights one potential exposure that can have an impact on respiratory health,” he said in a phone interview.

He noted that the neighbors who appeared to be the most affected by farm pollution were those who had chronic obstructive pulmonary diseases, which inflame the airways. These conditions include emphysema, chronic bronchitis and asthma.

Jackson said the findings would not prompt him to recommend that people living near large-scale farms consider moving, however.

“People should be aware of these exposures, and if they’re having respiratory symptoms associated with these sorts of exposures, it’s something to look into and have further evaluated,” he said.

The study appears at first glance to contradict a growing body of research that suggests children who grow up on farms may be at reduced risk of allergies and asthma, Jackson said.

But Smit said studies of children on farms have focused on smaller operations.

“There are also benefits from a farm environment,” she said. “But it depends on what kind of farms and pollution you’re looking at.”

Farms with 1,000 pigs, for example, create a completely different environment for children than a small family farm.

The factory farms “are emitting large-scale pollutants and dust,” she said. “Children are not going to play on these pig farms.”

Last week, government regulators in the Netherlands ordered poultry farmers to cut dust emissions by half over the next 10 years, she said.

“Farmers know something needs to be done to reduce pollution and the risks,” Smit said. “It’s very important to have a dialogue with farmers and the community.”

SOURCE: bit.ly/2qxUGWP American Journal of Respiratory and Critical Care Medicine, online May 10, 2017.