Military personnel deployed to Afghanistan and Southwest Asia experience a complex mixture of exposures, most notably particulate matter with an aerodynamic diameter <2.5 µm (PM2.5) from desert dust, which can lead to adverse respiratory effects, according to a report published in the Annals of the American Thoracic Society.

Since 2001, >2.7 million United States military personnel have been deployed in support of operations in Afghanistan and Southwest Asia (including Kuwait and Iraq). Land-based personnel have experienced elevated levels of PM and other inhalational exposures from multiple sources including desert dust, burn pit combustion, and other industrial, mobile, or military sources.

A workshop was conducted at the 2018 American Thoracic Society International Conference to identify key studies assessing postdeployment regulatory health, describe emerging research, and find knowledge gaps. Participants representing multiple disciplines, including pulmonary medicine and occupational and environmental medicine, discussed epidemiologic studies that demonstrated more frequent encounters for respiratory symptoms and airway disease after deployment compared with those not sent to the area, and case series that described postdeployment dyspnea, asthma, and a range of other respiratory tract findings.

Military personnel who have been deployed to these areas may experience reductions in pulmonary function as a result of such exposure. The workshop participants noted that in studies conducted by the Department of Defense, evidence suggests that more respiratory symptoms and obstructive lung disease (most commonly, asthma) occur after deployment. Other epidemiologic findings have shown an increased risk for new-onset asthma related to combat exposure in previously deployed military personnel. However, the relationship of asthma after deployment with specific exposures is unknown, as is the relationship with previous pulmonary function test abnormality or previous asthma diagnosis.

Participants also focused on constrictive bronchiolitis, which has been reported in the lung biopsies of certain members of the military who had been deployed. There was a heterogeneity of views among the workshop participants regarding the interpretation of the findings of constrictive bronchiolitis and its potential relationship with dyspnea and related symptoms after military deployment.

Nonetheless, the findings regarding estimated PM2.5 exposure do raise concerns about the future respiratory health of previously deployed military personnel, particularly since adverse respiratory health effects have been observed at lower PM2.5 concentrations than at those experienced during deployment. The authors noted that although there were multiple sources that contributed to PM2.5 exposure, desert dust was the predominant one.

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“The workshop concluded that the relationship of airway disease, including constrictive bronchiolitis, to exposures experienced during deployment remains to be better defined,” stated the authors. They added that, “Future clinical and epidemiologic research efforts should address better characterization of deployment exposures; carry out longitudinal assessment of potentially related adverse health conditions, including lung function and other physiologic changes; and use rigorous histologic, exposure, and clinical characterization of patients with respiratory tract abnormalities.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Garshick E, Abraham JH, Baird CP, et al. Respiratory health after military service in Southwest Asia and Afghanistan. An Official American Thoracic Society Workshop Report. Ann Am Thorac Soc. 2019;16(8):e1-e16.