Postmenopausal women are at risk of damaging their bones when exposed to air pollution, according to new research.

A study published in the Lancet journal last week found that elevated levels of air pollutants could lead to bone damage in postmenopausal women.

The researchers behind the prospective observational study wanted to determine how environmental factors, such as air pollution, could affect osteoporosis in elderly women.

After collecting data from 161,808 postmenopausal women enrolled in the Women’s Health Initiative, the team estimated the air pollution exposures of the participants based on their home addresses.

The team measured the participants’ bone mineral density using dual-energy X-ray absorptiometry upon enrollment. They then conducted follow-up measurements at year one, year three and year six.

After analyzing data, the scientists at Columbia University Mailman School of Public Health noticed how the air pollutants affected the bones of the elderly participants. Among the pollutants, nitrous oxide appeared to be the most alarming. It caused twice as much damage to the lumbar spine compared to normal aging.

“In this cohort study, higher levels of air pollutants were associated with bone damage, particularly on lumbar spine, among postmenopausal women. These findings highlight nitrogen oxide exposure as a leading contributor to bone loss in postmenopausal women, expanding previous findings of air pollution-related bone damage,” they wrote.

The damaging effects of the pollutants are believed to be caused by bone cell death triggered by oxidative damage and other mechanisms.

"Our findings confirm that poor air quality may be a risk factor for bone loss, independent of socioeconomic or demographic factors. For the first time, we have evidence that nitrogen oxides, in particular, are a major contributor to bone damage and that the lumbar spine is one of the most susceptible sites of this damage," study first author Diddier Prada, MD, Ph.D., associate research scientist in the Department of Environmental Health Sciences at Columbia Mailman School of Public Health, said in a news release.

It was not the first time scientists examined how air pollution affects human bones. Previous research claimed exposure to air pollutants could reduce bone mineral density and increase the risk of bone fracture. The team behind the new study said more research is needed to determine other people who may be at risk of bone damage due to air pollution.

"Improvements in air pollution exposure, particularly nitrogen oxides, will reduce bone damage in postmenopausal women, prevent bone fractures, and reduce the health cost burden associated with osteoporosis among postmenopausal women. Further efforts should focus on detecting those at higher risk of air pollution-related bone damage," said lead author Andrea Baccarelli, MD, Ph.D., the chair of the Department of Environmental Health Sciences at Columbia.