Hazardous gases: carbon monoxide, hydrogen sulphide and carbon dioxide

On this page:

• Requirements under the national law
• Toxic gas: is your vessel at risk?
• Risks and control measures
• Next steps

Toxic gas: is your vessel at risk?

Exhaust fumes from vessel engines, generators, appliances and sewerage systems produce gases that are toxic and highly explosive. These gases can build up, leading to poisoning, explosions and fires.

See which gas risks apply to your vessel.

Lessons from vessel incidents: In 2019, one person died on the Class 1 passenger vessel Lady Rose during a charter in Sydney Harbour. The likely cause of death was exposure to hydrogen sulphide that had filled the toilet cubicle through a faulty waterless hand basin trap.

Risks and control measures

Carbon monoxide poisoning 

Carbon monoxide is an odourless, tasteless and colourless gas.  It is produced when a carbon-based fuel, such as petrol, diesel, propane, charcoal or oil, burns. 

Inhaling high concentrations of carbon monoxide can cause death in minutes.  

Risks

• Engines, generators and fuel-burning appliances: These include:
  • BBQs, charcoal briquettes/beads and grills
  • outdoor heaters
  • gas lanterns
  • tools with gasoline engines (e.g. pressure washers, saws)
  • portable generators
  • boat engine exhausts.
• Confined areas: Never operate carbon monoxide-emitting appliances indoors or in small, poorly ventilated spaces.

Symptoms

Some common symptoms of carbon monoxide poisoning include:

• nausea
• vomiting
• headaches
• dizziness or weakness
• eye irritation
• fainting.

Symptoms of high exposure to carbon monoxide include:

• loss of consciousness
• seizures
• permanent brain injury
• death.

People with carbon monoxide poisoning can look like they are seasick or drunk.  If unsure, call for medical assistance. Failure to identify and treat carbon monoxide poisoning can result in death. 

Control measures

• Avoid being seated or standing close to engines or exhaust systems, particularly when the vessel is idling.
• Make sure passengers do not spend a lot of time on the swimming deck and ladder at the rear of the vessel due to nearby exhaust fumes.
• Only use fossil-fuel burning appliances, engines, tools and equipment outdoors. Consider other factors like wind direction. Keep fumes away from open windows and cabin doors.
• Dive boats with cylinder charging compressors need to ensure that the compressor air intake is well away from propulsion engine exhausts to reduce the risk of ignition.
• Monitor and service equipment regularly to make sure there are no leaks. Check equipment as part of the pre-start routines.
• Consider installing gas detection monitors.

Resources

• Call the Poisons Information Centre on 13 11 26 for advice 24/7
• Carbon monoxide poisoning factsheet
• Carbon monoxide (CO)

Hydrogen sulphide poisoning

Hydrogen sulphide is a colourless, flammable, corrosive, poisonous gas that smells like rotten eggs. It's produced naturally from decaying organic matter.

Exposure over a long period desensitises a person to the smell. Higher levels will dull a person's sense of smell instantly. Breathing in high concentrations of hydrogen sulphide can kill a person. 

Risks

• Sewerage systems: Hydrogen sulphide can be produced in bilge systems, oily water tanks and fuel tanks but it's most commonly produced in sewerage systems. This gas will continue to build in sewage tanks until they are emptied.
• Fishing vessels: Hydrogen sulphide can also be produced on fishing vessels by rotting fish, fish waste or offal.
• Low-lying, enclosed areas: Hydrogen sulphide is heavier than air and can travel along the ground. It collects in low-lying and enclosed areas with poor airflow.
• Ignition sources and sparks: Hydrogen sulphide is highly flammable. It can easily ignite and explode and must be kept away from ignition sources or sparks.

Symptoms

Common symptoms of hydrogen sulphide poisoning:

• headache
• dizziness
• staggering
• sudden collapse
• acute eye, nose and throat irritation
• shortness of breath
• tightness in chest
• wheezing
• loss of olfactory senses (loss of smell and taste).

Acute symptoms of hydrogen sulphide poisoning at high concentrations:

• convulsions
• pulmonary edema (fluid in the lungs)
• coma
• death (in very high concentrations almost instantly).

Control measures

• Complete a thorough risk assessment and make sure crew are aware of the safety measures in place.
• Pump out sewage tanks after each voyage/charter.
• Check that sewage tanks are empty prior to commencing each voyage. Empty them if they contain waste.
• Include the monitoring, maintenance, and servicing of sewerage systems in your vessel risk assessment in your SMS.
• Make the crew aware of hydrogen sulphide and other hazardous gases on board in the safety induction. Include procedures to manage situations where these gases are detected in the vessel’s emergency plan/procedures.
• Let the master know as soon as a rotten egg smell is first detected. Start your emergency procedures and call 000.
• Hydrogen sulphide will accumulate on lower sections in vessels because it's heavier than air. Stay clear of these zones and move to an open area in an emergency.
• Watch what's happening around you and be aware of the possibility of inhaling hazardous substances when dealing with incidents on board.  Contact HAZMAT for guidance as needed.
• Do not put yourself and your crew in danger when helping others. If someone has collapsed inside from any hazardous gases, go outside.

Resources

• Call the Poisons Information Centre on 13 11 26 for advice 24/7
• Hydrogen sulphide gas exposure factsheet
• Safety Advisory - Risks of hydrogen sulphide exposure on Domestic Commercial Vessels - Lady Rose

Carbon dioxide poisoning 

Carbon dioxide (CO2) is a naturally occurring gas. It's heavier than air and accumulates on the ground.  Like carbon monoxide, carbon dioxide is colourless, tasteless and odourless. 

We exhale carbon dioxide, and in low quantities it does not pose a risk to people.  However, a few minutes of exposure to high concentrations of carbon dioxide can be fatal, particularly if a person collapses to the floor or is working in low lying areas in a vessel.

Risks

• CO2 cylinders: Carbon dioxide contained in CO2 cylinders is commonly used in the hospitality industry to carbonate drinks such as on tap beers, ciders and post-mix soft drinks.
• Confined areas: Many passenger vessels use and store CO2 cylinders, usually in small cupboards. If there is a leak, gas emissions can build up and pose a serious risk to people when they open the cupboard or enter the confined area where these cylinders are being stored. Suffocation and possible death can occur within minutes. 

Symptoms

Acute carbon dioxide poisoning stops the respiratory and circulatory systems in the body which can cause:

• tachycardia (fast heart rate)
• cardiac arrythmias
• impaired consciousness.

More serious symptoms of high exposure to carbon dioxide are:

• convulsions
• coma
• asphyxiation
• death.

Control measures

• Include the use, storage and maintenance of CO2 in your risk assessment, emergency plans and crew induction within the vessel's SMS.
• Store CO2 cylinders in open, well-ventilated areas.
• Do not store CO2 cylinders in small rooms or cupboards without CO2 monitors.
• Check CO2 cylinders for leaks regularly.
• Make crew aware of the risks of CO2 exposure in your vessel induction and daily prestart briefings, and provide information on what to do in case there is a gas leak.
• Consider installing gas monitor devices near the source.

Resources

• Call the Poisons Information Centre on 13 11 26 for advice 24/7
• Gases in cellars and cool rooms

Next steps

1. Conduct a risk assessment to identify equipment, appliances and systems that create hazardous gases on your vessel.
2. Put storage and maintenance procedures in place to eliminate or reduce the risk to your crew and passengers.
3. Consider installing gas monitoring devices.
4. Induct and train crew, and educate hirers (Class 4) so they are prepared to deal with hazardous gas situations.
5. Record risks and controls in your SMS.