When we first meet Dory, she's just swimming around minding her own business when suddenly she bumps into Marlin and instantly offers to help him hunt down his son.
Chronic obstructive pulmonary disease (COPD) is a leading cause of death and disability internationally. Alveolar hypoxia and consequent hypoxemia increase in prevalence as disease severity increases.
Smoking cigarettes is by far the most common cause of emphysema. And emphysema is by far the most common cause of giant bullae in the lungs. There are limited cases of bullae appearing in the lungs as a result of bronchial illnesses from high air pollution levels, or occupational exposure to chemical fumes.