Not all units of measurement are equal, but the value of each unit is used for its intended purpose, so we have different units of measurement for each problem.
The atoms in air are combined with oxygen present in the air and when we inhale the air, oxygen is moved into the body then atoms in oxygen are carried by red blood cells the blood is pumped to the lungs and when oxygen is transported to the body organ, the atoms in lungs become the part of human cells.
