Military Inhalational Exposures Outside the Theater of Conflict and Chronic Respiratory Symptoms

Abstract

Importance: Deployment to Afghanistan and Southwest Asia has been associated with adverse respiratory health outcomes. However, the impact of inhalational exposures (eg, vapor, dust, gas, fumes), which are known correlates of reduced lung function and future chronic lung disease, during military service time outside this deployment period has not been assessed.

Objective: To assess military inhalational exposures during nonwartime routine activities and their associations with chronic respiratory symptoms.

Design, setting, and participants: This cross-sectional study used data from the US Department of Veterans Affairs Service and Health Among Deployed Veterans study. US veterans who served between October 7, 2001, and February 28, 2017; deployed to Afghanistan or Southwest Asia; and living near 6 Veterans Affairs sites were randomly selected from Defense Manpower Data Center records. Participants completed interviewer-administered multi-item questionnaires about 29 exposures related to active duty military service time when not deployed. Onsite visits occurred between April 27, 2018, and March 13, 2020, and analyses were performed between April 1, 2023, and February 10, 2025.

Exposure: Inhalation exposures during active duty military service time.

Main outcomes and measures: The main outcomes were chronic respiratory symptoms of dyspnea, wheeze in the previous 12 months, and chronic bronchitis. Using factor analysis, the 29 exposures were reduced to 20 items and categorized into 5 factors. Responses were scored ordinally (0, 1, 2) according to exposure prevalence and duration. Generalized linear modeling was used to explore associations between exposures and chronic respiratory symptoms.

Results: The sample included 1712 veterans (median [IQR] age, 37 [33-45] years; 1522 male [88.9%]) who had military service other than during their deployment to Afghanistan or Southwest Asia. The median (IQR) total active duty military service duration was 77 (57-128) months, with 82.8% of their service time spent outside the theater of conflict. The prevalence of dyspnea, chronic bronchitis, and wheeze was 7.0% (117 participants), 7.1% (121 participants), and 15.2% (260 participants), respectively. The most commonly reported exposure categories were combustion and ground dust (1014 participants [59.2%]), aircraft maintenance (812 participants [47.4%]), and heavy equipment maintenance (783 participants [45.7%]). Adjusted multivariable analyses identified significant associations between heavy equipment maintenance exposures and dyspnea (odds ratio [OR], 1.33; 95% CI, 1.06-1.68) and wheeze (OR, 1.29; 95% CI, 1.10-1.52). Aircraft maintenance exposures were significantly associated with wheeze (OR, 1.22; 95% CI, 1.01-1.47). No statistically significant associations were found between these exposures and chronic bronchitis.

Conclusions and relevance: This cross-sectional study shows significant associations between heavy equipment maintenance and aircraft maintenance inhalation exposures outside of deployment with chronic respiratory symptoms among US veterans. These findings suggest that certain military inhalational exposures may contribute to the development of chronic lung disease and that policy interventions to reduce such exposures may protect the long-term respiratory health of military personnel.

Figure 1.. Summary of Factor Analyses

The nondeployment questionnaire consisted of 29 questions and items. Nine items were removed due to low factor loading (eTable 2 in Supplement 1).

Figure 2.. Adjusted Multivariable Models of Associations Between Exposure Groups (Percent Exposed) and Respiratory Symptoms (Percent Prevalence)

Adjusted for age; sex; race and ethnicity; education; income; marital status; body mass index; smoking status; duration of deployment; and self-reported civilian workplace exposure to vapors, gas, dust, or fumes.