Daily Dose: Impact of Air Pollution on Bone Mineral Density in Women

Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

On March 2, 2023, we reported on a study published in eClinicalMedcine that was among the first to directly link levels of nitrous oxides (NO₂) and osteoporosis risk in women.

The study

Researchers conducted a prospective observational study using data from the Women’s Health Initiative Study (WHI), a highly ethnically diverse cohort of 168 808 postmenopausal women enrolled between September 1994 and December 1998. Using geocoded participant addresses, investigators estimated daily mean concentrations of and exposure to 4 criteria air pollutants: PM₁₀, NO, NO₂, and SO₂. Participants underwent bone mineral density (BMD) measurement (whole-body, total hip, femoral neck, and lumbar spine) via dual-energy X-ray absorptiometry at study enrollment and follow-up visits at years 1, 3, and 6. At study enrollment, 9041 women had available BMD and long-term air pollution data, reflecting a total of 32 663 visits.

Bayesian kernel machine regression analysis of associations at different anatomical sites revealed that only NO₂ was negatively associated with whole-body and lumbar spine BMD. Lumbar spine BMD decreased 0.026 (95% CI: 0.016, 0.036) g/cm² /year per 10% increase in 3-year mean NO₂ concentration. The magnitude of the effect, authors explained, would amount to a 1.22% annual reduction in BMD—nearly double the effects of age on any of the anatomical sites evaluated. The highest correlations across all the averaging periods assessed were for NO₂ and NO, according to the findings. The lowest correlations were found between SO₂ and PM₁₀ and between SO₂ and NO.

Note from authors

"Our results suggest that public health policies should aim to reduce air pollution in general but should be stronger in reducing nitrogen oxides exposure. 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 in this population. Further efforts should focus on detecting those at higher risk of air pollution-related bone damage."

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