Emphysema. Gross specimen of part of a lung with emphysema. Emphysema causes the tiny air sacs (alveoli) of the lungs to become damaged and enlarged, leading to the walls between them breaking down. This reduces the surface area for gaseous exchange, restricting oxygen uptake by the blood and leading to shortness of breath. This can develop into a serious lack of oxygen in the blood and cyanosis (blue colouring), or even respiratory and heart failure. The main cause of emphysema is cigarette smoking. The black colour of this lung suggests that the person was a smoker. Treatment is aimed at preventing further damage as emphysema is incurable.