Exposure to air pollution is known to cause a vast array of respiratory health problems, but in a new study, researchers at Columbia University's Mailman School of Public Health have determined that air pollution can also weaken bones.

The paper, published in The Lancet Planetary Health, is the first to document high rates of hospital admissions for bone fractures in communities with elevated levels of ambient particulate matter (PM2.5).

Unfortunately, as a press release for the study noted, risk of bone fracture admissions is greatest in low-income communities. In the U.S., air pollution is especially high in poorer communities.

For the study, researchers analyzed osteoporosis-related fracture hospital admissions among 9.2 million people between 2003 and 2010 and found that even a small increase in PM2.5 concentrations would lead to an increase in bone fractures in older adults.

A further eight-year followup of 692 middle-aged, low-income adults found that participants living in areas with higher levels of PM2.5 and black carbon (the soot that comes from gas and diesel engines, coal-fired power plants and other fossil fuel sources) had lower levels of parathyroid hormone (a key calcium and bone-related hormone) as well as greater decreases in bone mineral density than those exposed to lower levels of the two pollutants.

The study's authors pointed out that the World Health Organization considers osteoporosis the second leading cause of disability globally after cardiovascular disease.

The researchers noted that particulate matter can cause systemic oxidative damage and inflammation, which could accelerate bone loss and increase risk of bone fractures in older individuals. Just think of smoking cigarettes as an example. Smoking contains several particulate matter components and has been identified as a risk factor for osteoporosis and bone fracture.

“Decades of careful research has documented the health risks of air pollution, from cardiovascular and respiratory diseases, to cancer, and impaired cognition, and now osteoporosis," said Andrea Baccarelli, MD, Ph.D., chair of Environmental Health Sciences at the Mailman School and the study's senior author.

Baccarelli said that the best way to prevent air-pollution-related diseases is through policies to improve air quality.

"Among the many benefits of clean air, our research suggests, are improved bone health and a way to prevent bone fractures," he said.

Since genetic factors are not a major determinant of osteoporosis, the authors suggested that research on the disease should be broadened to examine the impact of environmental factors.

In recent weeks, the Indian capital of New Delhi has been blanketed by a thick cloud of smog. As EcoWatch reported, the air in New Deli has remained "hazardous" for days. Illegal crop burning, vehicle emissions, industrial pollution and dust from sprawling construction sites have contributed to the pollution emergency. By 11 am on Friday, the U.S. embassy air quality data for PM 2.5 showed levels had reached 550, while the safe limit is 50, according to U.S. embassy standards.