Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest provided . Mild opacity at the left lung base appears most compatible with atelectasis though difficult to exclude a very early pneumonia . Right lung is clear . No large effusion or pneumothorax . Heart size is normal . Mediastinal contours unremarkable . Bony structures are intact . No free air below the right hemidiaphragm .
    OUTPUT:
    
Left basal opacity most likely atelectasis though difficult to exclude a very early pneumonia .