What is the primary cause of injuries below the glottis?

The primary cause of injuries below the glottis is the inhalation of noxious chemicals found in smoke. When someone inhales smoke, particularly from materials that are burning, the toxic byproducts can directly irritate and damage the respiratory tract beyond the vocal cords, leading to respiratory complications. The materials being burned can release various harmful chemicals, such as carbon monoxide, hydrogen cyanide, and other irritants that affect lung tissue and the airways.

In contrast, thermal burns typically cause injuries above the glottis due to the high temperatures of heated air or smoke that can result in burns to the upper respiratory tract. Steam inhalation, while also potentially dangerous, usually leads to thermal injuries and is more localized to the upper airway. External trauma does not generally account for inhalation injuries, as it refers to physical injuries that do not involve inhalation of combustion products. Therefore, inhalation of noxious chemicals is recognized as a significant risk factor for lower airway injuries following fire exposure.