Irritant Gas Exposure

Irritant Gas Exposure is a topic covered in the 5-Minute Emergency Consult.

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  • An irritant is any noncorrosive substance that on immediate, prolonged, or repeated contact with respiratory mucosa will induce a local inflammatory reaction.
  • Respiratory irritants are inhaled as gases, fumes, particles, or liquid aerosols.
  • Inhaled irritants:
    • Pulmonary toxicity is determined primarily by their water solubility.
  • Inhalation accidents frequently involve a mixture of irritant gases as well as chemical asphyxiants:
    • Carbon monoxide
    • Hydrogen cyanide
    • Hydrogen sulfide
    • Oxides of nitrogen
  • Risk factors include exposure to potential irritants:
    • Occupational
    • Leisure
    • Intentional
    • Accidental
  • Pathophysiology:
    • Cellular injury through interaction with respiratory mucosal water with subsequent formation of acids, alkalis, and free radicals


  • Settings:
    • Industrial: Chemical manufacturing, mining, plastics, and petroleum industries
    • Home: Improper use or storage of cleaning chemicals
    • Fires: Combustion yields toxic gases.
    • Civil Disturbance: Riot control agents.
  • Immediate onset of upper airway inflammation with highly water-soluble irritant gases or with aerodynamic diameter >5 mm:
    • Ammonia (fertilizers, refrigerants, dyes, plastics, synthetic fibers, cleaning agents):
      • Immediate symptoms range from mild edema and erythema to full-thickness burns and airway obstruction.
    • Sulfur dioxide (fumigants used on produce, bleaching, tanning, brewing, wine making, combustion of coal, and smelting of sulfide-containing ores):
      • Combines with water, forming sulfuric acid.
    • Hydrogen chloride (formed during combustion of chlorinated hydrocarbons such as polyvinyl chloride):
      • Combines with water, forming hydrochloric acid.
    • Chloramine (generated when ammonia and bleach are mixed):
      • When exposed to moist surfaces, releases hypochlorous acid.
    • Acrolein (production of plastics, pharmaceuticals, synthetic fibers; formed during combustion of petroleum products, cellulose, wood, paper):
      • May cause protein damage via free radical production and sulfhydryl binding.
    • Formaldehyde (production of plywood, particle board, insulation; combustion product of gas stoves and heaters):
      • Combines with water to form sulfuric acid and formic acid.
    • Hydrogen fluoride (combustion of fluorinated hydrocarbons):
      • Depletes calcium stores, resulting in cell death.
    • Riot control agents (Capsaicin [OC], Chlorobenzylidenemalononitrile [CS], and Chloroacetophenone [CN]):
      • Lacrimation agents which cause temporary ocular discomfort.
  • Latent period of minutes to hours before onset of symptoms with irritant gases of intermediate water solubility or aerodynamic diameter of 1–5 mm:
    • Chlorine (product of chlorinated chemicals; bleaching agent):
      • Upper and lower airway damage after reacting with water to form hydrochloric and hypochlorous acids
  • Delayed onset of symptoms up to 24 hr after inhalation with irritant gases of poor water solubility or aerodynamic diameter <1 mm (with little or no warning of exposure):
    • Oxides of nitrogen produced:
      • In manufacture of dyes and fertilizers
      • By electric arc welding and gas blowing
      • By fermentation of nitrogen-rich silage (silo-filler's disease)
      • In combustion of nitrocellulose and polyamides
    • Phosgene/carbonyl chloride (arc welding and pesticide production: Combustion of chlorinated hydrocarbons and solvents)
    • Ozone (produced during arc welding)
    • Cadmium oxide (oxyacetylene welding and electroplating)

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