Occupational Blast Wave Exposure During Multiday 0.50 Caliber Rifle Course.

Area of Science:

• Military Medicine
• Occupational Health
• Neuroscience

Background:

• Military operations involving explosive events, such as breaching, expose personnel to blast overpressure (BOP).
• Previous research indicates BOP can transiently impair operator readiness, affecting cognitive function and response speed.
• Understanding BOP effects from specific weapon systems is crucial for personnel safety and performance.

Purpose of the Study:

• To evaluate the blast overpressure (BOP) effects of 50 caliber weapon systems on neurocognitive performance.
• To assess the relationship between BOP exposure levels and changes in reaction time and cognitive function.
• To identify potential aggravating factors, such as fatigue, influencing performance.

Main Methods:

• Twenty professional marksmen firing 50 caliber weapon systems during a 3-day training course.
• Exposure monitored using B3 blast gauges, recording over 500 shots.
• Neurocognitive performance assessed using the Defense Automated Neurobehavioral Assessment (DANA) Rapid, including Simple Reaction Time (SRT), Procedural Reaction Time (PRT), and Go/No-Go (GNG) tests, with pre- and post-training assessments.

Main Results:

• Significant variation in cumulative peak pressure (50-350 psi) and impulse (25-180 psi·ms) was observed.
• Daily exposure ranged from 4-27 shots, with hourly rates varying significantly.
• Procedural Reaction Time (PRT) and Go/No-Go (GNG) tests showed a cumulative increase in slowed reaction times and increased dispersion by the end of the day.
• No direct correlation found between cumulative pressure dosage and performance changes, though fatigue appeared to be an aggravating factor.

Conclusions:

• While some neurocognitive functions showed cumulative decrements, particularly PRT and GNG, these were not directly correlated with BOP dosage.
• Fatigue emerged as a significant factor influencing neurocognitive performance.
• Further investigation is required to understand the variability in individual responses, recovery periods, and longitudinal effects of heavy weapon system usage.