Asphyxia is defined as a condition in which insufficient or no oxygen and carbon dioxide are exchanged on a ventilatory basis. In essence, when the body or any vital part of the body is deprived of oxygen, asphyxia occurs.
Death arising from asphyxia alone is most often due to natural or accidental causes. As for natural causes, it is worthwhile to note that many diseases and infections can in fact hinder airways. As for accidental causes, foreign bodies like meat or bone can become trapped in the throat or windpipe, thereby blocking the airways and causing asphyxia in the process. Food particles are often the cause of accidental choking deaths in adults. On the other hand, choking deaths of children are normally derived from small plastic or metal toys in addition to food particles. In addition, pressure on the outside of the chest that restricts breathing can also cause asphyxia. This pressure can occur during cave-ins, building collapses, or traffic accidents.
Inhaling asphyxiants may also cause asphyxia. As the name implies, Asphyxiants are any types of poison which works by depriving human tissues of oxygen. Examples of asphyxiants include chemicals like ammonia, chloroform, carbon monoxide, and carbon dioxide. Sometimes these chemicals are the cause of suicidal or homicidal deaths. Homicide and suicide by asphyxia alone are rare. But in learning the reasons for death by asphyxia, anything suspicious must be pursued through background investigation and autopsy. Only then can the death be ruled accidental or natural.
N.B. Please kindly refer to my future posts under the "Crime Scene Investigation - Asphyxiation" series for further details on issues relating to homicide and suicide by asphyxia.