suffocation is a general term denoting a death brought about by a reduction of the oxygen content in inspired air. It is one cause of hypoxia. Smothering is often classified as a type of suffocation, in which air, and therefore oxygen, are prevented from reaching the lungs by obstructing the nose and the mouth.

The oxygen in the atmosphere can be displaced by other gases, for example in industrial and domestic fires. In such circumstances toxic gases such as carbon monoxide or cyanide produced by burning plastics may be liberated and accelerate the process of suffocation. Another example is the replacement of oxygen in the atmosphere by carbon dioxide, which may build up in grain silos when some technical fault develops. There may also be a greatly reduced oxygen content in the air at the bottom of deep wells.

Suffocation may also be the cause of death when oxygen is being used up and there is no fresh air supply. In ships' tanks nitrogen can replace oxygen as a result of the damp inner linings using up oxygen as rust is formed: entry into such an atmosphere can result in almost instantaneous death — usually this means someone has ignored health and safety regulations. Another cause is when a defective heating apparatus in an inadequately ventilated room has removed oxygen from the atmosphere — in such circumstances suffocation may be compounded by the apparatus producing carbon monoxide, which displaces oxygen from the blood. Or the oxygen may be used up by the victim, when someone — often a child — has inadvertently been confined in an enclosed space such as a cupboard or a discarded refrigerator or deep freeze. Another example is plastic bag suffocation which may be accidental, suicidal, or homicidal and results from the bag being placed over the head down to neck level. Death can again be very rapid. This is of relatively recent occurrence — and has led to the familiar warnings on all plastic packaging.

Smothering is the usual term for external obstruction to breathing — perhaps by a hand, a pillow, a gag, or a sheet of plastic — which prevents air, and therefore oxygen, reaching the lungs. Smothering by ‘overlaying’ of an infant in the parental bed was in the past assumed to be the cause of what would now be called cot death.

J. Hume Adams

suffocation (suf-ŏ-kay-shŏn) n. cessation of breathing as a result of drowning, smothering, etc., leading to unconsciousness or death (see asphyxia).