Airborne Hazards Exposures in the Southwest Asia Theater of Military Operations

On September 11, 2020 the National Academies of Sciences, Engineering and Medicine, Committee on Respiratory Health Effects of Airborne Hazards Exposures in the Southwest Asia Theater of Military Operations, released the subject Report. In part, the Report said that:

“Southwest Asia theater veterans were exposed to a broad range of potentially hazardous airborne agents. These include such regional environmental exposures as air pollution from dusts; local point and area sources such as traffic, waste management, and local industries; and the aeroallergens and microbial agents present in the theater. Exposures related to military operations are also contributors, such as exhaust from heaters, military vehicles, and aircraft as well as smoke from structural fires, explosions, burning oil wells, or burn pits.” Continuing,

“CONCLUSIONS REGARDING THE ASSOCIATION BETWEEN IN-THEATER AIRBORNE HAZARDS AND RESPIRATORY HEALTH OUTCOMES

The health effects of these airborne hazards were likely influenced by factors common to military operations in Southwest Asia. These effect modifiers include temperature extremes, psychosocial stress, sleep deprivation, and noise.

The committee formulated a list of 27 health outcomes for their literature review, delineated in Box S-2 [below]. The list included the conditions explicitly listed in the Statement of Task and those that the committee believed to be “of great concern to veterans.”

Of these outcomes, none met the criteria for sufficient evidence of an association. The evidence for respiratory symptoms—which included chronic persistent cough, shortness of breath (dyspnea), and wheezing—met the criteria for limited or suggestive evidence of an association for both veterans who served in the 1990–1991 Gulf War and those who served in the post-9/11 conflicts. Studies considered in previous National Academies reports were relatively consistent in reporting associations between deployment and more prevalent self-reported respiratory symptoms in theater veterans, and outcomes from more recent studies are largely in line with those findings. Importantly, a recent study that compared symptom reporting before, during, and after deployment found that the self-reported frequency of symptoms was increased both during and after deployment relative to pre-deployment. Many of the studies considered, however, were weakened by bias induced by the self-selection of their participants (which may have led to people being more likely to participate if they had respiratory symptoms than if they did not) and by the lack of control for cigarette smoking, which is known to exacerbate symptoms. These concerns, while serious, were consistent with a classification in the limited or suggestive category. Lastly, the committee

BOX S-2
Respiratory Health Outcomes Addressed

Non-Cancer Respiratory Disorders

Upper Airway Disorders

Rhinitis Sinusitis

Non-Infectious Lower Airway

Asthma
Chronic bronchitis
Chronic obstructive pulmonary disease

Interstitial Lung Diseases

Acute eosinophilic pneumonia Hypersensitivity pneumonitis Idiopathic interstitial pneumonia

Infectious Lower Airway

Acute bronchitis Pneumonia

Respiratory Symptoms

Chronic persistent cough Shortness of breath (dyspnea)

Respiratory Cancers

Esophageal cancer Laryngeal cancer

Other Outcomes

Sleep apnea
Vocal cord dysfunction

Constrictive bronchiolitis Emphysema

Idiopathic pulmonary fibrosis Pulmonary alveolar proteinosis Sarcoidosis

Tuberculosis

Wheeze

Lung cancer
Oral, nasal, and pharyngeal cancers

Changes in pulmonary function
Mortality due to diseases of the respiratory system

concluded that there is limited or suggestive evidence of no association between deployment to the 1990–1991 Gulf War and changes in lung function.

The committee found that there was inadequate or insufficient information to evaluate the association between service in the Southwest Asia theater and all of the remaining respiratory health outcomes it examined. While there are a variety of reasons for this that vary by the outcome under consideration, one prominent cause was the lack of good exposure characterization. Many studies used deployment to the theater as their only metric of exposure, and this undoubtedly led to people with widely different exposure experiences being grouped together for analysis purposes. Such grouping would be expected to diminish the possibility of observing an effect if one existed if there were large numbers of those with relatively low exposure compared with those with relatively high exposure.