Blast overpressure getting attention from lawmakers, Army

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By Margaretd. Regina

An Army reservist who killed 18 and wounded 13 in a mass shooting in Maine last October had signs of brain damage that likely came from blast overpressure — a little understood form of long-term injury that soldiers can develop from firing heavy weapons.

Now the physical and mental effects on troops exposed to blast overpressure from weapons are getting attention from the Army and Congress.

Lawmakers introduced a bipartisan bill earlier this week called the “Blast Overpressure Safety Act” which directs the Department of Defense to enact new measures to mitigate, protect and treat injuries for service members exposed to blast overpressures from weapon systems.

Research on repeated exposure to blast overpressure has linked the effects to impaired cognitive performance and decision-making ability, according to the Army’s Medical Research and Development Command which is designing a tool to help troops understand their exposure risks.

Sen. Angus King (I-Maine) said in a release that TBIs from explosive weapons are “common yet misunderstood.”

“In Maine, we know all too well the horrible tragedies that can occur, like in Lewiston, when TBIs are left untreated,” King said. 

The legislation introduced in the Senate mandates regular neurocognitive assessments throughout troops’ military careers, including baseline assessments before training. It also calls for blast overpressure and traumatic brain injury logs, data collection on brain injuries like related discharges, modifications to weapons to reduce blast exposure, training for high-risk troops on symptoms and mitigation techniques and retaliation protections for servicemembers seeking care.

The bill also calls for updating blast overpressure thresholds and the creation of a waiver system for those thresholds; mandatory training for medical and training personnel on blast overpressure, exposure and TBI; and expanding technologies for the Warfighter Brain Health Initiative pilot blast monitoring program.

The impacts of blast exposures on troop’s mental and physical health has slowly gained attention from lawmakers following the stand up of the Defense Health Agency’s Traumatic Brain Injury Center of Excellence and reports from major news outlets have highlighted the psychological and physiological effects of continuous, unmitigated exposure to artillery weapon systems and blast injuries on American troops.

On the service side, the Army is developing a Blast Overpressure Tool to give troops firing heavy weapons like mortars, rockets, rifles and breaching rounds guidance on how to protect themselves from the high-pressure shock waves, also known as “blast overpressure.” The tool will give users an estimate of the blast wave’s radius and safety risks from a particular weapon by using a computer model of the training environment.

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An analysis of the reservists’ brain tissue by Boston University researchers found evidence of traumatic brain injury which “likely played a role in his symptoms.”

Card’s family said in a statement that while the brain analysis does not fully explain his actions nor provides a reason for the “horrific suffering he caused,” they also said it helped them understand Card’s brain damage and “how it may have impacted his mental health and behavior.” 

The Army’s tool

Since 2000, nearly half a million troops have been diagnosed with TBIs from training or combat, according to the DOD.

During three months in 2023, the DOD treated servicemembers nearly 50,000 times for TBIs which are considered the “signature wound” of the wars in Iraq and Afghanistan, Sen. Susan Collins (R-Maine) said in a press release. 

For mild TBI, the most common diagnosis for American troops who served in Iraq and Afghanistan military, “the most important cause of brain injury was the long-term exposure to explosive weapons,” according to researchers.

Beyond the last two decades, TBI diagnoses are growing among U.S. troops stationed in Iraq and Syria for counter-terrorism operations who have been under rocket and ballistic missile attacks by Iranian-backed militias in the region since mid-October.

Once the prototype Blast Overpressure Tool has been fully validated, the plan is to expand it to include all the high-priority weapon systems – shoulder mounted assault weapons, rifles and machine guns, howitzers, mortars and breaches. 

Researchers began developing the tool with a small business after they discovered inconsistent safety guidance for individual weapons across the services. 

The DOD’s Blast Injury Research Coordinating Office is also creating a portable, pocket-sized flip book to illustrate the radius of blast overpressure zones of weapon systems and ammunition for crew members, observers and instructors and lists recommended personal protective equipment.

Dr. Raj Gupta, BIRCO’s deputy director said the flip book will be useful for trainers and observers who are “potentially exposed to blast overpressure every time a Service Member fires their weapon” which for some that means several blast exposures each day.

The flipbook began with data collected by Walter Reed Army Institute of Research on blast overpressure exposure during live fire training of four weapon systems: the shoulder fired M136 AT4 recoilless anti-tank weapon, the M120/M121 120mm mortar, the M107 and MK15 .50 caliber sniper rifles and breaching charges. 

The data was collected by wearable sensors and high-fidelity stationary probes around the firing zone which was then turned into 3D simulations of blast exposures on human bodies and 2D maps of the blast radius with various pressures. The Army office has two patents for the exposure tool.

The office is collaborating with the Army and Marine Corps to integrate the blast tool into the services’ suite of geospatial applications which are used to plan safe range exercises since blast overpressure exposure mitigation is currently not addressed.

Gupta has discovered gaps in the safety and mitigation procedures during the experimental phase of weapon development which are included in the federal legislation.The DOD does not require federal researchers or private contractors to measure blast overpressure as part of a given weapon system’s research, testing and engineering and acquisition process. There is also zero data collection of exposure to blast overpressure on civilians or contractors during the development process. 

Blast exposure could also result in auditory injuries, according to research published in the Military Medicine journal by Gupta. The paper recommended that the DOD do more for blast exposure-related injuries like hearing loss, tinnitus, and central processing deficits and cited a 2021 Department of Veterans Affairs benefits report which had tinnitus and hearing loss as the most prevalent service-connected disability.

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