This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations and should not be used as or considered legal advice. Health and safety inspectors apply these laws based on the facts they find in the workplace.


Firefighters may be called on to respond to incidents involving the mixing of chemicals to create hydrogen sulphide in an enclosed space.


Firefighters must wear appropriate PPE to protect themselves from an elevated level of hydrogen sulphide gas, which is immediately dangerous to life and health at a level of 100 parts per million (ppm).

Actions for employers

Employers should develop operational guidelines/procedures which consider the following:

  • recognizing when a hydrogen sulphide solution has/may have been used in a non-fatal suicide attempt or a death by suicide
  • warning signs for the presence of hazardous materials, that when mixed, produce this gas; such as, pesticides and muriatic or hydrochloric acid
  • how to identify the presence of hydrogen sulphide itself – as it has a distinctive odour
  • mandatory use of self-contained breathing apparatus in certain circumstances
  • treatment protocols for assisting patients who are exposed/contaminated
  • protocols for responders who are exposed/contaminated
  • scene investigation to prevent exposure of other tenants/emergency responders

Hydrogen sulphide

Here are some basic facts about this gas:

  • colourless gas with a notable odour similar to rotten eggs or sewer gas
  • detectable at low levels, measured in parts per million (ppm)
  • the odour threshold is 0.13 ppm
  • although pungent at first it quickly deadens the sense of smell at higher concentrations
  • heavier than air and tends to accumulate at the bottom of poorly ventilated spaces
  • levels dissipate quickly with the introduction of air currents, such as positive pressure ventilation
  • considered a broad-spectrum poison as it can poison several different systems in the body, although the nervous system is most affected
  • flammable/explosive
  • exposure to lower concentrations can result in eye irritation, sore throat and cough, nausea, shortness of breath and fluid in the lungs
  • an elevated level of 100 ppm is immediately dangerous to life and health due to its toxicity

Personal protective equipment for hydrogen sulphide exposure

Employers must ensure firefighters wear:

  • self-contained breathing apparatus should be used when entering a suspected contaminated area
  • protective clothing should be worn that provides adequate skin protection which could include structural firefighting turnout gear or splash suits

Additional precautions

Consider these additional precautions when responding to events or developing operational guidelines/procedures:

  • air sampling equipment, if available, can be used to determine the presence or absence of hydrogen sulphide before entering a space
  • eliminate ignition sources whenever possible
  • agitation of the chemical mixture may produce further off-gassing so continued use of self-contained breathing apparatus is recommended even with zero readings on the monitor sensor

There have been no incidents of fire reported with hydrogen sulphide suicides, and it is believed that concentrations do not typically reach the lower explosive limit except at close proximity to the mixing container.

Decontamination of firefighters and others

Decontamination for first responders should be set up appropriately for the degree of contamination encountered at the scene.

Hydrogen sulphide poses a minimal risk through skin absorption and also a minimal risk of secondary contamination for first responders.

Consider the following measures:

  • at a minimum, skin should be washed with water for three to five minutes
  • if eyes or skin appear to be irritated, continue to flush with water during medical observation and transport to a nearby medical facility
  • use soap and water to decontaminate anyone who has been exposed to vapours
  • remove and double bag clothing
  • launder contaminated clothing and personal protective equipment before reuse, following the recognized procedures for doing same

Care of victims of chemical suicides

Fire Services may be called upon for assistance with body recovery, removal, or decontamination, depending on local jurisdiction protocols. Police must be consulted before the body is moved.

Contamination of victims of chemical suicides may be more acute and decontamination may require more time and attention than other types of victims.

Consider the following measures:

  • wear appropriate PPE
  • remove and double bag the victim’s clothing
  • decontaminate the body as dictated per normal standard operating procedures or guidelines
  • cover the victim with a sheet – do not use a body bag for transporting victims unless they must be transported in an enclosed vehicle in which they will be occupying the same space as the driver

Note: individuals may off-gas from their lungs after they have been dead for a significant period of time - this may pose a risk for those transporting the deceased and those performing autopsies

Applicable regulations and acts



Read firefighters guidance notes: