A recent study conducted by researchers at National Jewish Health has found that exposure to burn pit smoke during military deployments is linked to increased levels of carbon-based particles in the lungs of post-9/11 veterans with distal lung disease.
The research, published in Scientific Reports, utilized a quantitative microscopy technique to directly measure particulate matter within lung tissue samples. The findings showed that veterans suffering from deployment-related lung disease had significantly higher amounts of anthracotic pigment—carbon-based particles—compared to healthy individuals. The study also established a strong association between these elevated particle levels and reported exposure to burn pit smoke.
"Burn pits were widely used during post-9/11 military operations, yet linking specific inhalational exposures to long-term lung disease has been challenging," said Cecile S. Rose, MD, MPH, senior author of the study and pulmonologist at National Jewish Health. "This study provides objective, tissue-based evidence that burn pit smoke exposure leaves a measurable impact in the lungs that may contribute to disease development."
Researchers compared surgical lung biopsy samples from 24 post-9/11 veterans with deployment-related lung disease against those from smokers with respiratory bronchiolitis and healthy controls. They applied a validated quantitative microscopy for particulate matter (QM-PM) method to assess two indicators: anthracotic pigment fraction (retained carbon-based particles) and birefringent dust density (retained silica and silicate particles).
After accounting for age differences, the results indicated that mainly non-smoking veterans with lung disease had anthracotic pigment levels similar to those found in smokers with respiratory bronchiolitis and more than three times higher than those seen in healthy controls. The elevated pigment burden was closely linked to reported burn pit smoke exposure but not associated with other potential sources such as sandstorms or diesel exhaust.
"This approach allows us to move beyond self-reported exposure histories and directly measure what remains in the lung tissue," said Jeremy T. Hua, MD, MPH, lead author of the study. "The strong association between burn pit smoke exposure and anthracotic particle burden is particularly compelling."
Lung diseases affecting small airways and alveoli—including bronchiolitis and emphysema—are being increasingly recognized among previously deployed service members. While earlier studies have identified high mineral dust content in some veterans' lungs, this new research highlights carbonaceous particles from burn pit smoke as a possible factor in developing these conditions.
"These findings help clarify how complex deployment-related exposures may translate into lasting lung injury," Hua added. "They also underscore the importance of continued research, monitoring, and care for veterans experiencing unexplained respiratory symptoms."
