Phosgene

Objectives

To understand the physical properties of phosgene and the immediate management of suspected phosgene intoxication. 

Scope

This guideline describes the management of suspected phosgene exposure. There are separate guidelines for the management of acute lung injury (ALI) / acute respiratory distress syndrome (ARDS) which must be applied in severe cases of phosgene exposure. 

Audience

This guideline is intended for the use of registered healthcare professionals fulfilling a general role in a forward medical locations or in an Emergency Department on deployed operations. 

Initial Assessment & Management

Properties

Phosgene is a highly toxic pulmonary agent that exists as a vapour above its boiling point of 7.4°C1. At temperatures below that it may condense to a liquid but rapidly vapourises on warming. It is colourless and the vapour is 3.5 times denser than air, accumulating in sheltered, low lying areas. It has an odour of new mown hay and because it reacts with water, is far less effective when deployed in rain2.


Symptoms and Signs

Even at high concentrations, inhalation can spare the upper airways and victims are often asymptomatic immediately following exposure3. Dyspnoea, florid pulmonary oedema and cyanosis are prominent early phases. Fluid losses are so profound that patients are severely hypovolaemic with haemoconcentration, and cyanosis gradually becomes less evident, manifesting as a grey pallor. Symptoms and signs may be delayed, manifesting on light exertion hours after exposure4. Phosgene reacts with water to form hydrochloric acid which can cause minor irritation of eyes and upper airways. 


Initial Management

Depending upon the inhaled dose, respiratory distress may not manifest for up to 48h5. This requires close observation of potential patients and the worried well. If the CXR is normal at 24h they can be discharged. Oxygen supplementation may be required to maintain oxygen saturation above 94%. 

  • There are no tests for, or biomarkers of phosgene exposure
  • Long latency necessitates prolonged observation of potential phosgene casualties
  • Salbutamol has been shown to worsen phosgene induced acute lung injury7
  • Aggressive IV fluid resuscitation may be required
  • Steroids can be considered within 6 hrs of exposure but are of little to no benefit

Advanced Assessment & Management

Measures to improve oxygenation include continuous positive airway pressure (CPAP)6 and can be escalated to invasive ventilation using established ARDS Net strategies. Severely affected patients will have profound fluid losses and require fluid resuscitation to euvolaemia. Hypoxaemia refractory to the above measures is an indication for referral for extracorporeal membrane oxygenation (ECMO) if available. 

  • There are no tests for, or biomarkers of phosgene exposure
  • Long latency necessitates prolonged observation of potential phosgene casualties
  • Salbutamol has been shown to worsen phosgene induced acute lung injury7
  • Aggressive IV fluid resuscitation may be required
  • Steroids can be considered within 6 hrs of exposure but are of little to no benefit

Paediatric Considerations

No specific considerations

Last reviewed: 18/09/2026

Next review date: 18/09/2027

References
  1. BOC. Safety Data Sheet: Phosgene MSDS Nr: 331-00-0002BOC(U). BOC, Priestley Road, Worsley, MANCHESTER M28 2UT: British Oxygen Company; 2000.
  2. Cowell E. CHEMICAL WARFARE AND THE DOCTOR—I. British Medical Journal. 1939;2(4109):736.
  3. Vedder EB. The Medical Aspects of Chemical Warfare. Waverly Press, Baltimore MD: Williams & Wilkins Company; 1925. 327 p. 
  4. Nicholson-Roberts TC. Phosgene use in World War 1 and early evaluations of pathophysiology. BMJ Military Health. 2019 Jun 1;165(3):183-7. 
  5. Grainge C, Rice P. Management of phosgene-induced acute lung injury. Clin Toxicol (Phila). 2010;48(6):497-508. 
  6. Graham S, Fairhall S, Rutter S, Auton P, Rendell R, Smith A, Perrott R, Nicholson Roberts T, Jugg B. Continuous positive airway pressure: an early intervention to prevent phosgene-induced acute lung injury. Toxicology Letters. 2018 Sep 1;293:120-6. 
  7. Grainge C, Brown R, Jugg B, Smith A, Mann T, Jenner J, et al. Early treatment with nebulised salbutamol worsens physiological measures and does not improve survival following phosgene induced acute lung injury. Journal of the Royal Army Medical Corps. 2009;155(2):105-9.