Air Pollution Linked to Poor Bone Health in Study

Politicians must act to tackle air pollution, the co-author of a study linking it to poor bone health has urged.

Past studies have found associations between air pollution—including particulate matter as well as ozone, nitrogen dioxide, and sulfur dioxide—and conditions such as lung cancer, acute lower respiratory infections, strokes, heart disease and chronic obstructive pulmonary disease. But less is known about the potential effects on bone health, according to the authors of the paper published in the journal JAMA Network Open.

The study involved 3,717 people aged 35 on average, living in 28 villages near the southern Indian city of Hyderabad. They were recruited for the research project between 2009 and 2012. On average, the participants were annually exposed to 32.8 μg/m3 of particulate matter PM2.5—particulate matter measuring up to 2.5 micrometers in diameter—which is more than the safe level of 10 μg/m3 set by the World Health Organization.

Researchers invited participants to a clinic where they had special x-ray scans to detail their bone mineral content and density. The investigators used a model to estimate the pollution the volunteers were exposed to on average.

The team found a negative association between PM2.5 air pollution exposure and bone mineral content and bone mineral density. The team believes breathing in combustion particles could trigger an imbalance of free radicals and antioxidants in the body, known as oxidative stress, as well as inflammation.

The study comes as India struggles with air pollution levels in its capital Delhi. Last November, levels of PM 2.5 hit their highest levels in three years.

Otavio T. Ranzani, first author of the study and researcher at the Barcelona Institute for Global Health, told Newsweek the team was surprised to find the association in a relatively young population. The magnitude of the effect was higher for those aged over 40, he said, as this is the period where bone mass loss is greater, particularly in post-menopausal women.

But Ranzani said the study was limited because the team couldn't measure bone mass over time, and therefore couldn't assess how it changed.

He went on to point out that the average adult filters roughly 10,000 liters of air through their lungs every day. If the air is contaminated, the accumulation of pollutants could trigger immune responses, he explained.

"This chronic status of inflammation can damage our bone health," he said. Ranzani said people should keep up habits good for the bones such as exercising, eating enough calcium and maintaining vitamin D levels.

"Importantly, we should push politicians to put on the agenda measures to mitigate and reduce air pollution," he said.

Last year, several studies also linked air pollution to a higher risk of mental illness, including depression.