Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP upright and lateral views of the chest were provided . There is improvement in aeration in the left lower lung with persistent linear density likely relating to persistent atelectasis . No effusion . No pneumothorax . The right lung is clear . Cardiomediastinal silhouette is normal . Bony structures are intact . No free air below the right hemidiaphragm .
    OUTPUT:
    
Improved aeration in the left lower lung with persistent linear opacity at the site of prior pneumonia , which could represent residual atelectasis .