hygiene, the science of preserving health. The subject embraces all agencies affecting the physical and mental well-being of humans. It involves, in its personal aspect, consideration of diet and consumption of water and other beverages; clothing; work, exercise and sleep; personal cleanliness; and mental health. In its public aspect it deals with climate; soil; character, materials and arrangement of dwellings; heating and ventilation; removal of waste matters; medical knowledge on incidence and prevention of disease; and disposal of the dead.