Blast Overpressure: Risk Mitigation for Maximum Performance

U.S. Soldier watches a 40-pound shaped charge detonation during Operation Tiger Dawn at Camp Mackall, N.C., Oct. 6, 2025. The controlled blast conducted under strict safety protocols helps engineers validate breaching techniques and sustain the XVIII Airborne Corps’ readiness to project decisive combat power. (U.S. Army photo by Sgt. Nolan Brewer)

In 2024, the Department of War (DoW)—formerly the Department of Defense—and the Department of the Army published new requirements aimed at increasing awareness, improving understanding, and driving materiel solutions to reduce and monitor blast overpressure (BOP) effects on personnel. This guidance builds on the All Army Activities (ALARACT) published in 2022 and reflects the DoW and Army’s overarching strategy: mitigate BOP risk while preserving operational readiness.[1][2]

Figure 1. Typical Blast Wave

BOP is the sharp rise in atmospheric pressure produced by an explosive detonation or weapon firing, generating a shock wave that travels faster than the speed of sound. Figure 1 illustrates a typical pressure-versus-time curve of a typical blast wave at a singular point, showing an instantaneous rise in pressure (peak overpressure), followed by an exponential decay toward zero and a subsequent period of negative pressure (underpressure). Although not depicted, rarefaction (release) waves and reflective waves—created as the blast interacts with surrounding structures—are also present. Impulse, defined as force exerted over time, is measured across the duration of the blast event, while peak pressure represents the highest pressure recorded. Reflective waves vary based on the environment and can significantly influence the overall blast profile. While understanding blast-wave physics is essential for breaching and demolition operations, this article focuses on the health effects experienced by personnel within the blast radius.

Why does understanding the characteristics of the blast wave matter? Peak pressures above 4 pounds per square inch (PSI) can cause injury. For example, a pressure differential of approximately 5 PSI across the eardrum can result in rupture, and exposure to 15 PSI can lead to lung damage. Current research indicates that personnel should avoid any exposure exceeding 4 PSI. As PSI increases, so does the risk of brain injury, lung or kidney damage, and gastrointestinal disruption. Repeated exposure below the 4-PSI threshold—or exposure to any component of the blast wave—may also contribute to chronic health issues over time. These can include tinnitus, irritability, memory and concentration difficulties, and sleep disturbances (see Figure 2).

Such conditions are challenging to diagnose because their signs and symptoms overlap with those of other genetic or environmental factors (such as dementia or prolonged exposure to high-noise environments). Additionally, the medical and industrial hygiene communities still lack a definitive threshold at which symptoms begin to manifest. This uncertainty is a key driver behind the development of the Cognitive Monitoring Program (CMP) for BOP.

Cognitive Monitoring Program

The CMP is the Army’s prescribed method for tracking brain health. Cognitive testing began in 2007, initially focused on predeployment and postinjury assessments to address brain injuries associated with improvised explosive devices (IEDs) encountered during deployments. In June 2024, as part of the shift toward continuous monitoring across a Soldier’s career, the Army began establishing cognitive baselines for all new Soldiers at training installations. The current assessment tool is the Neurocognitive Assessment Tool (NCAT), similar to its predecessor the Automated Neuropsychological Assessment Metrics (ANAM). Each individual’s baseline is unique, and comparisons with subsequent assessments help identify cognitive changes over time.

The August 8, 2024, DoD Policy Memorandum for Managing Brain Health Risks from Blast Overpressure identifies several occupational specialties at increased risk of BOP. These include Engineer–General Engineer Officer (12A) and Combat Engineer (12B); Chemical, Biological, Radiological, and Nuclear Officers and Specialists (74A/D); Military Police (31B); and Explosive Ordnance Disposal Officers and Technicians (89A/D) among others, including civilian equivalents. Soldiers and civilians in any military occupational specialty (MOS) who serve as instructors on BOP-producing weapon systems are also considered high-risk. Within the Army Engineer Regiment, Bridge Crewmembers (12Cs) and Quarry Specialists (12Gs) warrant inclusion due to their routine work with explosives.[3]

The memorandum also lists high-BOP-producing weapon systems, such as the M2A1 .50-caliber machine gun, the M136A1 anti-tank 4 (AT4), and various breaching explosives. Personnel assigned to these systems are likewise at increased risk. High-risk Soldiers must complete an annual cognitive reassessment, while all others are required to retest at least every three years. Similar to annual hearing evaluations, cognitive monitoring is only reported to medical providers when a deviation from a baseline is detected. Commanders can track their units’ cognitive assessments through the Medical Protection System (MEDPROS) Commander’s Portal under the NCAT indicator.[4][5]

In addition to ANAM testing, the Army is developing wearable blast sensors. U.S. Army Transformation and Training Command (T2COM), working in coordination with the functional communities, is refining the requirements for these sensors across the total Army. This effort, combined with ongoing market research and related initiatives, will help shape the next steps of the program. Once fielded, these wearables will provide critical blast-exposure data to Soldiers, commanders, and the medical community.

Leadership Responsibilities

Leaders are responsible for managing risk, identifying hazards, and implementing appropriate control measures—and BOP is no exception. Because BOP exposure often occurs at lower levels during routine training, it can become overlooked or unaddressed simply due to familiarity. In addition to existing mitigation measures, educating the force on BOP and its effects is the essential first step in reducing this risk.[6]

Demo Range Mitigations

Figure 3. Minimum Safe Distance K-Factors for Blast Overpressure

To mitigate peak pressure during demolition training, apply the minimum safe-distance formula in Graphic Training Aid (GTA) 05-10-033 (March 2024), using a K-factor of 30 for training and 20 for combat. Establishing adequate standoff distance remains the most effective measure for reducing BOP risk. Personnel must wear appropriate personal protective equipment (PPE), including a helmet and hearing protection. Helmet orientation matters: the crown should face the blast to help deflect the wave. Any other orientation can create reflective waves inside the helmet, increasing the risk of brain injury. Environmental factors—such as confined spaces (urban terrain) and overcast conditions—can amplify reflective waves. When these conditions are present, leaders should consider adjusting or shortening training to limit exposure.

BOP-Producing Weapon Ranges

When conducting ranges with high BOP-producing weapons, limit the number of personnel in proximity to the weapon, avoid firing more rounds than required for qualification (do not conduct a spendex, and adhere to the authorized round count for each operator), and ensure that all personnel wear appropriate PPE. Increase the use of simulators and training aids prior to live-fire execution. Employing suppressors can reduce BOP exposure. Additional engineering solutions are currently under development to further lower BOP levels for various weapon systems, and once validated, these updates will be incorporated into applicable technical manuals.

Exposed to BOP?

If you or a Soldier under your leadership is exposed to BOP, seek medical attention immediately. Early evaluation and adherence to medical guidance can help reduce long-term effects, and recovery outcomes improve when issues are identified promptly. If diagnosed with a traumatic brain injury, follow all prescribed protocols before returning to duty. Additional information is available at Health.mil - Traumatic Brain Injury Center of Excellence. If you begin experiencing any signs or symptoms of low-level blast exposure, as shown in Figure 2, consult your healthcare provider. The Department of Veterans Affairs now offers benefits to support those with blast-related injuries.