When designing protective equipment for soldiers and law enforcement, blast threats are often overlooked, with the focus primarily on ballistic, stab, and fragment protection. However, primary blast injuries, which affect air-filled organs like the lungs and gastrointestinal tract, can be exacerbated by certain thoracic protective equipment. Using an anthropomorphic mannequin, BOPMAN (Blast OverPressure MANnequin), the effectiveness of a soft ballistic vest against blast threats of varying intensities was evaluated. The study involved detonations ranging from 85 g to 4 kg of C-4, with blast wave impulses from 17 kPa·ms to 237 kPa·ms. Both unprotected and protected conditions were tested, revealing a constant amplification factor of 1.36 ± 0.24 on metrics when the mannequin was equipped with a soft ballistic vest (SBV). Scenarios that were deemed safe without protection became hazardous when the vest was used. Estimated lung–injury risk has increased, ranging from 0.1 % to 29.3 %, suggesting pulmonary contusion and accompanying edema. High-speed videos showed the vest protection “slapping” the mannequin’s chest upon shock wave impact, likely due to an air gap between the vest and chest, which may explain the amplification of blast effects.