The HVAC systems in buildings is similar to the respiratory system in human bodies as they both control the filtration, movement, and temperature of air throughout the system. For filtration, the human body uses small hairs in the nose to filter out particles from the air. Oxygen then moves through the body through blood vessels and capillaries. HVAC systems have filters in place to filter out particles and other harmful pollutants from the air, and the ducts move air throughout the building.