- Advisory number:
- Date issued:
- 05 May 2021
- Issued by:
- Dr Angie Bone, Deputy Chief Health Officer (Environment), Victoria
- Issued to:
- Health professionals and the community
- Carbon monoxide is an odourless, colourless gas that may cause a range of symptoms including headache, nausea and vomiting, flushing, muscle pain, weakness, shortness of breath, dizziness, coordination difficulties, confusion, or chest pain if inhaled.
- Symptoms of poisoning are non-specific and can be mistaken for a flu-like illness or even food poisoning. Very high levels of carbon monoxide can cause loss of consciousness, seizures and death.
- Medical professionals are therefore requested to exercise a high level of suspicion if compatible symptoms are related to the use of gas heaters and to follow the recommendations in this Advisory.
- Read the guide: to assist in the diagnosis and management of carbon monoxide poisoning.
- Colder weather will increase the use of gas heaters and potentially increase the risk of carbon monoxide poisoning, where an open flued gas heater is faulty.
- As any gas heater can become faulty, Energy Safe Victoria recommends all are serviced and tested at least once every two years by a licenced or registered gasfitter with an endorsement to service Type A gas appliances.
- Gas heaters should not be left running continuously overnight.
- Installing a carbon monoxide alarm is a useful back-up measure but does not replace the need for regular servicing of gas heaters.
- Portable outdoor gas appliances should never be used indoors. Remember BBQ heat beads produce carbon monoxide and should never be used inside for cooking or heating purposes.
What is the issue?
Any gas heater has the potential to leak carbon monoxide into the indoor living area. This includes old and new heaters, central heating units, space heaters, wall furnaces and decorative appliances such as decorative log fires.
Patients may attend general practitioners or emergency departments with symptoms or concerns about carbon monoxide poisoning. As these symptoms are non-specific and frequently occur as a result of other more common conditions, it is possible carbon monoxide exposure is not considered and the patient sent home with serious or potentially fatal consequences. The source of carbon monoxide may be in the home, in the car due to a leaking exhaust system, in the workplace, or in caravans. Malfunctioning gas heating and cooking appliances are the most common sources in the home.
All gas heaters and decorative log fires need to be serviced at least every two years by a licenced or registered gasfitter with an endorsement to service Type A gas appliances. A licenced gas fitter checks the installation including testing for carbon monoxide leakage.
Open-flued gas heaters, especially models on the , may increase indoor carbon monoxide levels under certain conditions. The combination of inadequate room ventilation, and operating bathroom or kitchen exhaust fans at the same time as an open flued gas heater, may draw unsafe levels of carbon monoxide into the living area. The risk is further increased if the heater is faulty or the flue is blocked.
Who is at risk?
All people and pets are at risk of harm from carbon monoxide if exposed.
Children, pregnant women and unborn babies, older people and those with chronic illnesses are at increased risk from carbon monoxide exposure.
People may be exposed to carbon monoxide as a result of a fault or blockage of any type of gas heater or decorative log fire. This risk is reduced with regular biennial servicing.
In certain homes with an open flued gas heater, running a bathroom exhaust fan or kitchen rangehood can generate enough negative room pressure to draw exhaust gases that would otherwise rise out of the flue/chimney, into the indoor living area. Checking for this forms part of the heater’s regular service and testing. Airflow through clear wall vents or a partially opened window may prevent this from occurring.
Carbon monoxide is an odourless, colourless gas that may cause a range of symptoms including headache, nausea and vomiting, flushing, muscle pain, weakness, shortness of breath, dizziness, coordination difficulties, confusion, or chest pain. Symptoms are non-specific and can be mistaken for a flu-like illness or even food poisoning. Very high levels of carbon monoxide can cause loss of consciousness, seizures and death.
Anyone concerned about carbon monoxide poisoning should:
- immediately turn off all gas appliances (heater, stove)
- open the 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
- have gas appliances urgently tested safety by a licenced or registered gasfitter with an endorsement to service Type A gas appliances.
Long-term exposure to low levels of carbon monoxide can also lead to impaired thinking and concentration, emotional lability, irritability and impulsiveness.
Diagnosis can be challenging as symptoms are non-specific and occur with other more common conditions.
Health care workers should exercise a high level of suspicion if:
- symptoms are temporally related with the use of a gas heater
- symptoms also occur in other occupants of the household (including pets)
- symptoms improve when outside the house
- there are concerns about the functioning of the heater - heater appears faulty or has not been maintained/ serviced
- there has been new installation of an exhaust fan or the recent blocking of wall vents.
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 where available 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.
Advise the patient to arrange an urgent service and test of their gas appliances before they are used again.
Advise the Environmental Health Unit, Department of Health on 1300 761 874 of all elevated results.
For medical professionals:
- exercise a high level of suspicion if symptoms are temporally related with the use of a gas heater, occur in other occupants of the household (including pets), or the patient reports feeling better when away from their home
- test for carboxyhaemoglobin levels in any person with suspected carbon monoxide poisoning
- ensure the patient is aware of a possible faulty gas appliance which is urgently checked before reused
- advise the Environmental Health Unit, Department of Health on 1300 761 874 of any cases of confirmed carbon monoxide poisoning in the home.
The new Residential Tenancy Regulations 2021 require rental providers 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 rectified and serviced by a licenced or registered gasfitter. To view these models, go to .
To check whether you have an open-flued gas heater, contact the manufacturer for advice or check with your local gasfitter.
Carbon monoxide alarms
Carbon monoxide alarms can be a useful back-up precaution but should not be considered a substitute for the proper installation and maintenance of gas heating appliances. Select alarms that meet US or EU carbon monoxide standards (UL2034 (US) or EN50291 (EU), and carefully follow instructions for installation, maintenance and use.
Clinicians should advise the Environmental Health Unit, Department of Health and Human Services on 1300 761 874 of any cases of confirmed carbon monoxide poisoning.
Public housing tenants with gas heating can contact the Department’s Housing hotline on 1800 148 426 for information.
Anyone experiencing symptoms that may be due to carbon monoxide exposure should seek medical advice or call the NURSE-ON-CALL on 1300 60 60 24 (24/7). In an emergency call 000.
Reviewed 09 March 2022