Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low , causing bronchovascular crowding . A new opacity has developed in the posterior segment of the left lower lobe , partially obscuring the descending thoracic aortic interface in resulting in increased opacity overlying the thoracic spine on the lateral view . . There is no effusion or pneumothorax . The aorta is tortuous , unchanged from prior . The cardiomediastinal silhouette is otherwise normal . Imaged osseous structures are intact . No free air below the right hemidiaphragm is seen .
    OUTPUT:
    
Focal left lower lobe pneumonia .