Answer:
the pulmonologist mainly talking about the after-effects of the pulmonary disease known as Emphysema or chronic obstructive pulmonary disease (COPD).
The lungs constitute of tiny air sacs called alveoli, which are normally stretchy and like springy. during inhalation, the alveoli expand like tiny balloons and exhalation actually is a passive task (takes no effort) as the alveoli get back to their original size.