Asphyxia is a condition of severely deficient supply of oxygen to the body. In the absence of remedial action it will very rapidly lead to unconsciousness and death. Asphyxia is the same as suffocation. Anoxia means the pathological state in which tissues do not get (enough of) oxygen.

Asphyxia in humans is a medical emergency.

Causes of asphyxia can include:

• Physical obstruction of the passage of air to or from the lungs:
  • Crushing or constriction of the chest or abdomen
  • Choking
  • Drowning
  • Strangulation, or external constriction of the neck or throat, e.g. by a rope (as in hanging), hands, or a constrictor snake
  • Reduction of the airways due to anaphylaxis or asthma
  • Inhalation of vomit
  • Positional asphyxia
  • The extremely dangerous and frequently lethal practice of erotic asphyxiation, also called "breath control play"; including autoerotic asphyxiation
• Breathing in low oxygen environments, for example:
  • the filling of cryogenic vessels with liquified, oxygen-free gases such as nitrogen in an enclosed space.
  • workers climbing down into a fermentation vat in a brewery, not realising the vessel has filled with carbon dioxide gas.
  • workers climbing down into the holds of ships that contain heavier than air, oxygen-free gases.
  • the misuse or failure of diving rebreathers where the breathing gas contains insufficient oxygen.
  • breathing a diving, hypoxic breathing gas mixture in shallow water where the partial pressure of oxygen is too low to support consciousness. A hypoxic "bottom gas" is designed only to be breathed at depth.

• Contact with a pulmonary agent or cyanogenic compound
• A seizure which stops breathing activity
• Sleep apnea

Problems during childbirth can lead to the newborn experiencing asphyxia.

Prolonged asphyxia can result in brain damage even when it does not cause death.

See also

• hypoxia (medical)
• oxygen depletion (aquatic ecology)

Recently, asphyxia by carbon monoxide has been a popular method, especially in Japan where many gather together in suicide pacts

BBC News: 9 Die in Japan 'Suicide Pacts'

The suicide pact in the article used the increasingly popular way of performing this particular asphyxiation. A small grill, or hibachi is filled with coals, and allowed to completely burn in a small air tight room, or vehicle. The carbon monoxide levels quickly reach lethal levels, and reportedly kills with little to no discomfort.

In the past, before catalytic converters began being installed on most vehicles, carbon monoxide asphyxiation was done by running a tube from the exhaust of a vehicle through the window. When the window and tube were properly sealed, this too would cause a fast death. This method is now losing popularity due to the availability of grills and coals.