Emphysema is a chronic lung condition in which the lungs' natural airspaces, called alveoli, become larger but decrease in number. The tissue surrounding the alveoli loses elasticity so that the airspaces can no longer expand and shrink as usual. This reduces the amount of oxygen transferred by the lungs to the bloodstream, making it more difficult for you to breathe.
Emphysema usually results from exposure to toxins like cigarettes as well as air pollution, dust, chemical fumes, and irritants. Older adults are more likely to be affected and many people who have emphysema are not aware that they have it.