Minimal Subsegmental atelectasis is seen at lung bases and if it is
not get treated it can cause pnemonia. In the lungs a bunch of grapes linke air sacs knows as aveoli are present which stay open all the time. when you dont breath deep long these air sacs get collapse and seen at the lung bases in subsegments which is known as subsegmental atelectasis.
The treatment of this is easy with the help of spiroometer. if you use it by taking 10 deep breaths every hour at the morining time.