Smoke inhalation is the breathing in of harmful fumes (produced as by-products of combusting substances) through the respiratory tract.

[7] Some reports also show increased rates of death and injury in children, due to their lower physical and mental capabilities.

[2][4] Some of the signs and symptoms of smoke inhalation injury include recent fire exposure followed by cough, wheezing, stridor, confusion, difficulty breathing, low oxygen saturation, smoke debris (especially on face and/or in saliva), burns (especially of the face), singed facial or nose hairs, and/or hoarse voice.

[2][6] A careful history can be helpful in determining where the fire occurred and therefore, what chemical fumes could have been inhaled with accompanying systemic toxicities.

Acute Respiratory Distress Syndrome (ARDS) is a relatively delayed complication of smoke inhalation injury caused by chemical fumes inducing an inflammatory response in the lung tissue, especially the small air sacs known as alveoli where critical gas exchange occurs.

Damage to lower airways, air sacs, and lung tissue is due to an inflammatory cascade in response to the noxious chemicals which causes a variety of downstream effects such as increased secretions and exudative material thus clogging the airways and/or air sacs, collapse of air sacs (atelectasis), vascular permeability leading to pulmonary edema (fluid in the lungs), bronchoconstriction, activation of the coagulation cascade, and impaired function of the mucociliary escalator.

[2][3][5][6] Inhalation of hot fumes can cause thermal damage to tissues, usually limited to the upper respiratory tract (above larynx).

[2][3][4][6] Carbon monoxide poisoning is the most common systemic toxicity after smoke inhalation, and can cause organ failure from lack of oxygen (often heart attack).

Additionally, carbon monoxide decreases the ability of oxygen to dissociate from hemoglobin to diffuse into tissues, thus causing hypoxia.

[10] Carbon monoxide (СО), which is absorbed by the lungs, diffuses into the capillaries and dissolves in the plasma and erythrocytes, binding to haemoglobin.

[11] In addition, carbon monoxide released at the tissue level binds to mitochondrial enzyme systems, resulting in the inability of cells to utilise oxygen.