Study Warns of the Risk of Carbon Monoxide Poisoning in the Military

Preventable CO exposures present a “unique and potentially lethal” risk for active duty service members and their beneficiaries.


Carbon monoxide (CO)—colorless, odorless, tasteless and highly toxic—is one of the most common causes of unintentional poisoning deaths in the US. Researchers who described their analysis of CO-related incidents in the military for the Medical Surveillance Monthly Report say military activities, materials, and settings pose “unique and potentially lethal sources of significant CO exposure.”

They reported on episodes of CO poisoning among members of the US Armed Forces between 2009 and 2019 and expanded on reports that dated back to 2001. Their analysis included reserve members and nonservice member beneficiaries.

Over the 10 years, there were 1,288 confirmed/probable cases of CO poisoning among active component service members, 366 among reserve component service members, and 4,754 among nonservice member beneficiaries. The highest number of active-duty members with CO confirmed/probable poisoning were reported at Fort Carson, Colorado (60) and NMC San Diego, California (52).

Of the confirmed/probable cases among active-duty members, 613 were classified as having unintentional intent, 538 undetermined intent, and 136 self-harm intent. One was due to assault. Most of the cases were related to work in repair/engineering occupations. Although the majority of sources were “other or unspecified,” motor vehicle exhaust accounted for 17% of the confirmed cases and all of the probable cases. Similarly, in the reserve component and among nonservice member beneficiaries, vehicle exhaust was the second-most common source.

The researchers found that CO poisoning-related injuries/diagnoses in the military often involved a single exposure that affected multiple personnel. For example, 21 soldiers showed symptoms during a multi-day exercise at the Yukon Training Center.

Excessive CO exposure is “entirely preventable,” the researchers say. Primary medical care providers—including unit medics and emergency medical technicians—should be knowledgeable about and sensitive to the “diverse and nonspecific” early clinical manifestations of CO intoxication, such as dizziness, headache, malaise, fatigue, disorientation, nausea, and vomiting. High CO exposure can cause more pronounced and severe symptoms, including syncope, seizures, acute stroke-like syndromes, and coma.

It’s important to remember, the researchers add, that increased oxygen demand from muscular activity exacerbates the symptoms of CO exposure, but individuals at rest may experience no other symptoms before losing consciousness.

An editorial comment notes that the full impact of morbidity and mortality from CO poisoning is difficult to estimate. For one thing, because the symptoms can be so nonspecific, clinicians may not consider CO poisoning when patients present for care.

This study differs from previous ones in that it uses code data from both the Ninth and Tenth Revisions of the International Classification of Diseases . Such data, the editorial comment says, can be used at national and Military Health System–wide levels with relatively few resources, providing useful information on trends and risk factors that can be used in designing interventions

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