I believe this is Chronic Bronchitis focusing primarily in the lower lung fields bilaterally. Could possibly be Bronchiolitis obliterans but not BOOP, bearing in mind I'm not a radiologist... I don't think it's pneumonia, TB, carcinoma or nodules, etc.
i think chronic broncholitis with some of congestion on secretion -mucus- in the lumen especially at secondary and tertiery bronchioles