How do thin alveolar walls help oxygen and carbon dioxide move between air and blood?

The thin walls of the pulmonary alveoli are essential for efficient gas exchange, which occurs through the process of diffusion.12

Because oxygen has relatively low solubility, it requires a large surface area and a very thin barrier to move effectively between the air and the blood. The alveolar membrane is approximately 0.5 micrometers thick—about 1/100th the diameter of a human hair—which minimizes the distance gases must travel.12

Diffusion is driven by the difference in partial pressures of gases between two locations, with molecules moving from an area of higher concentration to an area of lower concentration. By providing a minimal physical barrier, these thin walls allow oxygen to rapidly enter the pulmonary capillaries from the alveoli, while carbon dioxide simultaneously diffuses out of the blood into the alveoli to be exhaled.321