Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral chest radiographs demonstrate airspace abnormality in the left lower lobe , which superimposes upon the spine on the lateral view . There is no pleural effusion or pneumothorax . The cardiac silhouette and mediastinal contours are normal .
    OUTPUT:
    
Mild left lower lobe airspace opacity , which could represent pneumonia or atelectasis .