A lap belt pretensioner for a lap belt configured to secure an occupant of a vehicle seat includes a pyrotechnic device. The pyrotechnic device is configured to generate a force directed to tension the lap belt around the occupant and emit an exhaust gas including particulates at high pressure and high temperature as a byproduct of the generated force. The lap belt pretensioner also includes a housing configured to retain the pyrotechnic device and defining an exhaust passage configured to expel the exhaust gas from the lap belt pretensioner. The lap belt pretensioner additionally includes a shield arranged over the exhaust passage and configured to collect and/or deflect the emitted particulates and dissipate heat energy thereof. A vehicle having the vehicle seat mounted to the vehicle structure and employing the seatbelt system is also provided.