Before revision: Uptake of gaseous pollutants 250px The diffusion of from the air in the lungs to the bloodstream, and diffusion of from the bloodstream back out to the lungs is an essential part of human respiration.
After revision: Uptake of gaseous pollutants upright=1.15 The diffusion of from the air in the lungs to the bloodstream, and diffusion of from the bloodstream back out to the lungs is an essential part of human respiration.