Body & HealthFact
Your chest holds a surface the size of an apartment.
Your lungs are made of around 480 million tiny sacs called alveoli. Together they offer about 70 square metres of exchange surface, folded into one ribcage. The wall between air and blood is thinner than a thousandth of a millimetre, so oxygen and carbon dioxide diffuse across it in fractions of a second.
Useful: That huge, thin surface explains why smoke and fine dust reach the lungs so directly.
Source: en.wikipedia.org