Can a Pulse Oximeter Detect Carbon Monoxide?

If your CO alarm sounds or you suspect exposure, leave immediately for fresh air and call 9-1-1 from outside. Do not wait for a pulse oximeter reading or search for the source. Follow emergency responders’ instructions about returning. Public Health Agency of Canada: what to do if you suspect CO exposure.

Why this matters as heating season begins

Early October is a practical time to review home safety before regular furnace and fireplace use. Carbon monoxide is an invisible, odourless gas produced by burning fuels. Furnaces, fireplaces, water heaters and vehicle exhaust can be sources; poorly maintained or improperly vented equipment can allow CO to accumulate indoors. Health Canada describes common CO sources.

This is a seasonal preparedness article, not a report of a new outbreak or a measured surge in poisonings. It addresses a useful home-monitoring question: which device answers which safety question?

Why a normal SpO2 reading cannot rule out CO poisoning

SpO2 is a pulse oximeter’s estimate of blood oxygen saturation. Standard devices use light to estimate oxygenation, but cannot reliably distinguish the forms of haemoglobin involved in carbon monoxide exposure. BC Emergency Health Services warns that standard pulse oximetry can therefore be misleading. Read the BCEHS carbon monoxide guidance.

Carbon monoxide attached to haemoglobin is called carboxyhaemoglobin. Clinicians can use specialised testing to measure it. The US Centers for Disease Control and Prevention distinguishes conventional two-wavelength pulse oximeters from specialised CO-oximetry, and explains that diagnosis also depends on exposure history and clinical findings. A consumer oxygen reading is not a substitute for that assessment. CDC clinical guidance on CO poisoning.

Three devices, three different roles

• Standard pulse oximeter: estimates blood oxygen saturation and pulse; it does not establish that a home is free of CO.
• Household CO alarm: monitors the surrounding air and warns of carbon monoxide. It does not diagnose the people in the building.
• Clinical CO-oximetry: specialised testing used as part of evaluating suspected poisoning.

These distinctions follow Health Canada’s pulse oximeter guidance, its CO alarm guidance and CDC guidance on diagnostic testing.

Symptoms deserve attention even when a device looks reassuring

Health Canada lists headaches, tiredness, flu-like symptoms and shortness of breath among possible effects of CO exposure. Dizziness, chest pain and difficulty thinking may also occur. These symptoms have other possible causes, so a symptom checklist alone cannot diagnose poisoning. Health Canada: symptoms of exposure.

If several people in the same space feel unwell, that is useful information to tell emergency responders. Do not use a reassuring oxygen number to dismiss a possible exposure or delay leaving. CDC discusses exposure history and similar symptoms in multiple people.

A short fall home-safety checklist

1. Check your CO alarms. Choose alarms certified for use in Canada, follow installation instructions, test them regularly and check replacement dates.
2. Arrange appliance maintenance. Have fuel-burning appliances professionally inspected at least annually or as their manufacturer directs.
3. Keep outdoor equipment outdoors. Never run a generator or barbecue inside a home or garage, and never idle a vehicle in an attached garage.
4. Discuss the exit plan. Make sure household members know to leave when the CO alarm sounds and call for help from outside.

See Health Canada’s prevention checklist for details. Ask your local fire service about the alarm placement requirements that apply to your home.

Where a ToronTek pulse oximeter fits

The featured ToronTek G64+ Pulse Oximeter is a fingertip device, shown to illustrate the type of home monitor discussed here. It is not presented as a carbon monoxide detector or a way to assess suspected poisoning.

For routine oxygen monitoring, Health Canada advises following device instructions and discussing use and interpretation with a healthcare professional. Readings can be affected by factors such as movement, cold hands, nail polish and skin pigmentation. Your care plan should explain when and how to seek help. Health Canada: using a pulse oximeter safely.

Frequently asked questions

Can a pulse oximeter replace a CO alarm?

No. They measure different things. Use a certified household CO alarm for environmental warning; do not use an SpO2 number as an all-clear after a possible exposure. Health Canada alarm advice; BCEHS pulse oximetry limitation.

Should I recheck my oxygen before calling for help?

Not when an alarm sounds or CO exposure is suspected. Leave, call 9-1-1 from outside and follow emergency instructions. PHAC emergency steps.

Do I need to buy a pulse oximeter for heating season?

It is not a CO-safety measure. Focus on alarms, maintenance and a household response plan. Discuss any separate need for oxygen monitoring with your healthcare provider.

Disclaimer: This article is for educational and informational purposes only and is not intended as medical advice, diagnosis, or treatment. It should not replace guidance from a qualified healthcare professional. If you have symptoms, a medical condition, or concerns about your health, consult a licensed healthcare provider or seek urgent medical care when appropriate.