Pulmonary contusion or Primary Blast Injury can result from exposure to blast overpressure. The development of improved protection requires the ability to evaluate pulmonary response at the tissue level. A detailed numerical torso model was developed and used to predict response and the potential for injury resulting from short duration loadings. Long duration blast loading (duration > 10ms) is not common;​ however, the associated injury data necessary for model calibration is the most consistent from various sources in the literature. The first version of the torso model was not able to consider long duration loading due to the large tissue deformations. To address this issue, a hyperelastic tissue model was integrated with a bulk model to address long duration loading. The model was evaluated for long duration overpressures to provide an injury threshold. This model was subsequently investigated for varying overpressures, demonstrating increased predicted injury with increased overpressure. Injury was predicted to decrease for decreasing duration below 10ms. Above 10ms, the injury prediction was relatively constant in agreement with experimental data, and explained by the wave transit time in the lungs. This study expands the range of applicability of a detailed thorax model to predict the potential for primary blast injury, and an enhanced constitutive model for lung tissue to include bulk effects has been proposed.