5.5% of all intoxications occur as a consequence of inhaling a toxic substance (gases, fumes, vapours or aerosols), in particular asphyxiant and irritant gases. Gases are absorbed through the lungs and are metabolized or biochemically transformed in the body under the influence of various enzymatic processes. They are excreted by the lungs (carbon monoxide, cyanides, hydrogen sulphide) or through the kidney and stool. Simple asphyxiants (carbon dioxide) cause anoxic hypoxia in high concentrations, whereas chemical asphyxiants (carbon monox­ide, hydrogen sulfide, cyanides) cause tissue hypoxia. Most of the lethal cases are the con­sequence of acute carbon monoxide poisoning, which can also result in late neurological sequelae. Water- or less water-soluble irritant gases primarily irritate the mucous membranes of the upper respiratory tract and are a frequent cause of acute and chronic poisonings in industry, households and traffic. In addition to local irritant effect such as cough, hoarse­ness, dyspnea, tracheobronchitis, glottis edema, acute upper airway obstruction, chemical pneumonitis and toxic pulmonary edema, they can also cause systemic effects such as headache, nausea, vomiting, confusion and dizziness, and in severe cases even respiratory arrest and life-threatening ventricular arrhythmia. In all gas poisonings, removal of the victim from the contaminated area is the first measure, followed by basic and advanced life support, includ­ing oxygen therapy, and the administration of antidotes and symptomatic therapy.