Density-based analysis of PPE imaging data. A Representative axial, sagittal, and coronal CT slices from PPE-exposed and age-matched controls. B Average Hounsfield unit (HU) density distributions for control and PPE-exposed groups. C Volume of the lung region of interest (ROI). D Quantification of percentage of volume with density values less than -400HU, A.K.A. percentage volume of low attenuation (%VLA), signifying severe airspace enlargement. **p < 0.01, ***p < 0.001 by two-tailed t-test compared to age-matched controls.