Blast overpressure exposure poses a significant occupational risk to military personnel and can cause negative effects to Force Health and Readiness. Most blast exposure occurs during training, where repeated low‑level blast differs from single high‑intensity blasts but may cumulatively harm brain health. Monitoring and documenting blast exposure is therefore essential to understanding long‑term effects and protecting warfighters throughout and beyond their careers. The RTG HFM‑338 developed a three-stage development of guidelines strategy to mitigate military occupational brain health risks from repetitive blast exposure. These three stages are expert-based (current), knowledge-based, and experience-based. The current report contains the expert‑based guidelines. The group produced three products: 1) The Interim Exposure Guidelines define expert‑based exposure thresholds, identifying limits for peak overpressure, cumulative impulse, and generalized blast exposure values. 2) The Operational