3.1
Respiratory disease affects 1 in 5 people and is the third biggest cause of death in England. Some lung conditions are classified as obstructive, affecting a person's ability to breathe out all the air in their lungs quickly enough. Asthma and chronic obstructive pulmonary disease (COPD) are the most common obstructive airway conditions. Other lung conditions may be classified as restrictive, in which a reduced lung volume restricts a person's ability to inhale air. Idiopathic pulmonary fibrosis is an example of a restrictive lung condition. Some conditions may be both obstructive and restrictive (for example, COPD–pulmonary fibrosis overlap).