What Is Carbon Monoxide?

Carbon monoxide (CO) is a colourless, odourless and tasteless gas which is a by-product from incomplete combustion of any fuel which contains carbon. Common sources of CO include gas water heater, gas stove, exhaust from automobile or any other appliances that burn fuel.

Why Is Carbon Monoxide Dangerous?

You cannot smell, see or taste CO, but CO can be lethal. As little as 0.4% concentration of CO in the air can cause unconsciousness and death in a few minutes. CO is absorbed through the lungs and transported by the bloodstream to other parts of the body. Its presence prevents blood from carrying oxygen to the body tissues and causes hypoxic damage. .

Who Are At Risk of Carbon Monoxide Poisoning?

All people are at risk for CO poisoning. The following groups are more susceptible to its effects:

• Infant and young children;
• Pregnant women;
• Elderly people;
• People with cardiovascular or respiratory disease; and
• People with haematological disease that affects oxygen uptake or transport, e.g anaemia.

What Are the Symptoms of Carbon Monoxide Poisoning?

The health effects depend on the duration of exposure and the concentration of carbon monoxide inhaled.

Typical symptoms of exposure to low levels of carbon monoxide include:

• Headache;
• Dizziness;
• Tiredness; and
• Nausea.

Higher concentration of carbon monoxide can lead to:

• Impaired vision;
• Disturbed coordination;
• Unconsciousness;
• Brain damage; and
• Death.

Prevention Tips

• Have your fuel burning appliances installed and regularly serviced by qualified technicians.
• Make sure that all fuel-burning appliances are vented and / or the room is well ventilated.
• Check the exhaust system of your car regularly.
• Do not stay in an idled car with the engines switched on and all windows closed.
• Be alert to the symptoms of CO poisoning. Seek medical advice immediately if in doubt.

In Case of Suspected Poisoning:

• Keep calm;
• Seek your doctor's advice immediately;
• Call 999 emergency hotline immediately under safe condition if the patient's condition is serious, or the person is not arousable or is not breathing.

This publication is produced by the Hong Kong Poison Control Network.