Carbon monoxide poisoning

What is the issue?

Any gas appliance, gas heater, wood heater or fire-place, equipment or items powered with a gas or petroleum engine, have the potential to leak carbon monoxide, especially if they are used incorrectly or are faulty. This can cause a health risk when they are used in enclosed or poorly ventilated areas, such as inside the home or in a caravan.

Symptoms of carbon monoxide poisoning are non-specific and can be confused with other more common conditions. This increases the potential that carbon monoxide exposure is not identified by health professionals which may have serious or potentially fatal consequences.

Open-flued gas heaters, as well as wood heaters, where air from within the home is drawn in to feed the fire, may increase indoor carbon monoxide levels under certain conditions. Negative room pressure can occur when there is inadequate room ventilation in the home and a kitchen rangehood or bathroom exhaust fan is operating. The combination of this occurring at the same time as operating an open-flued gas heater or wood heater, may draw unsafe levels of carbon monoxide into the living area via the heater’s flue/chimney. The risk is increased if the heater is faulty or the flue/chimney is blocked.

Checking for negative room pressure should be part of regular gas heater service and testing. This is especially important if you live in a renovated or weather sealed house with an open-flued gas heater. Airflow through clear wall vents or a partially opened window may prevent negative room pressure occurring.

In July 2022, Energy Safe Victoria banned the sale and supply of new open flued gas heaters that do not meet new Australian Standards. This Standard requires newly manufactured open flued gas space heaters to shut down within 15 minutes to prevent carbon monoxide spillage if the appliance is operating in a negative pressure environment.

Refer to the Energy Safe Victoria's safety alert list for models of open-flued gas heaters that should be checked by a qualified gas fitter immediately.

Who is at risk?

All people and pets exposed to carbon monoxide can experience carbon monoxide poisoning.

Children, pregnant women and their unborn babies, older people and those with chronic illnesses such as heart and lung disease, are at increased risk of severe health impacts from carbon monoxide poisoning.

Symptoms

Carbon monoxide poisoning can cause a range of symptoms including headache, nausea and vomiting, skin flushing, muscle pain, weakness, shortness of breath, dizziness, coordination difficulties, confusion, or chest pain. Symptoms can be mistaken for flu-like illness or food poisoning.

Very high levels of carbon monoxide can cause loss of consciousness, seizures and death.

Long-term exposure to low levels of carbon monoxide can also lead to impaired thinking and concentration, emotional lability, irritability and impulsiveness.

Anyone concerned that they may have carbon monoxide poisoning should:

• Immediately turn off all gas appliances.
• Open doors and windows to ventilate the area.
• Leave the property, keeping the doors and windows open if possible.
• Seek medical advice immediately or call NURSE-ON-CALL on 1300 60 60 24 (24/7). In an emergency call 000.

Diagnosis

Diagnosis can be challenging as symptoms are non-specific and may occur with other more common conditions.

The diagnosis of carbon monoxide poisoning is based on history and examination, in conjunction with an elevated carboxyhaemoglobin level, as determined by venous blood analysis or a fingertip carboxyhaemoglobin monitor.

Measure carboxyhaemoglobin levels in any case of suspected carbon monoxide poisoning when the patient is first seen, as levels decline over time. Note that carboxyhaemoglobin may be elevated after smoking cigarettes.

Recommendations

• All gas heaters need to be serviced at least every two years by a licensed or registered gasfitter who is qualified to service Type A gas appliances. A licensed gas fitter checks the installation including testing for carbon monoxide leakage. Check that they are accredited before work commences.
• In accordance with the Residential Tenancy Regulations 2021, rental providers are required to arrange gas safety checks of all gas installations and fittings in rental properties by a licensed or registered gasfitter every two years.
• Gas heaters that are subject to a safety alert from Energy Safe Victoria should not be used unless these heaters have been serviced and deemed safe by a licensed or registered gasfitter. To view these models, go to Energy Safe Victoria safety alert list.
• To check whether you have an open-flued gas heater, contact the supplier or manufacturer or check with your local licensed gasfitter.
• Gas heaters should not be left to run continuously overnight.
• DO NOT:
  • Bring portable appliances designed for outdoor use inside your home or caravan. This includes barbeques, the use of heat beads, and portable patio heaters.
  • Leave cars idling in basements or garages attached to the house.
  • Use gas stoves, hotplates or ovens to heat homes.
  • Block flues or chimneys even if they are draughty as blockages allow carbon monoxide into the home.
• Only burn natural wood that is dry and not treated. Consider using alternatives to wood fire heating.
• Installing a carbon monoxide alarm is a useful back-up measure but does not replace the need for regular servicing of gas heaters. Select alarms that meet US or EU carbon monoxide standards (UL2034 (US) or EN50291 (EU), and carefully follow instructions for installation, maintenance and use.

For health professionals:

Exercise a high level of suspicion of carbon monoxide poisoning if:

• Symptoms are temporarily related to the use of a gas/wood heater, or other gas/petroleum fuelled appliance/item, used in an enclosed space.
• Symptoms also occur in other occupants of the household (including pets) or in an adjoining property.
• Symptoms improve when outside the house.
• There are concerns about the functioning of the heater or appliance – where they appear faulty or have not been maintained/serviced.
• A new exhaust fan has been installed or wall vents recently blocked.
• A portable heating or cooking device designed for outdoor use, has been used indoors.

Seek advice from the Victorian Poisons Information Centre on 13 11 26. This is a 24/7 service that can assist in diagnosis and management of any suspected case.

Advise the patient to arrange an urgent service and test of their gas appliances by a licensed or registered gas fitter before they are used again. If the incorrect use of a wood heater or other gas/petroleum fuelled appliance or item is suspected, advise the patient to stop its use immediately and refer them to this advisory.

Advise the Environmental Health Unit, Department of Health on 1300 761 874 of all elevated results.

Clinical information

The department has developed a guide Could it be carbon monoxide poisoning? to assist GPs in the diagnosis and management of carbon monoxide poisoning.

For more information about diagnosing carbon monoxide poisoning - Think carbon monoxide (The Medical Journal of Australia)

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