Asphyxiation is primarily caused by which condition?

Asphyxiation is primarily caused by oxygen deficiency, which means that the body is not receiving enough oxygen to maintain normal physiological function. This lack of oxygen can occur in various scenarios, such as drowning, choking, or being in an environment with insufficient breathable air. When the body's tissues and organs do not receive adequate oxygen, it can lead to unconsciousness and death if not corrected promptly.

The other conditions listed—excessive heat, radiation exposure, and chemical burns—while serious and potentially life-threatening, do not directly cause asphyxiation. Excessive heat may lead to heat stroke or heat exhaustion, radiation exposure can result in radiation sickness, and chemical burns typically lead to injury of the skin or internal organs, but none of these conditions primarily result in the absence of oxygen, which is the defining factor in asphyxiation.