Inhaled toxins frequently cause asphyxiation and can be classified further as chemical asphyxiants, simple asphyxiants, and pulmonary irritants.
Chemical Asphyxiants include Hydrogen Sulfide and cyanide. Hydrogen sulfide typically presents with a sulfur-like smell, while cyanide is typically presented in the burning of plastics.
Simple Asphyxiants are anything which replaces oxygen in the atmosphere, including carbon monoxide or dioxide, methane, helium, or nitrogen. These may be present in a mine or other industrial setting, and may classically present as an unconscious worker who was attempting to rescue another unconscious worker.
Irritant gases cause pulmonary irritation from coughing to diffuse lung injury. Irritants are categorized by their solubility; highly soluble irritants typically have strong scents because they are easily mixed into the upper airway, while less soluble irritants are typically less rapid in onset and will result in lower airway complaints.