Carbon monoxide (CO) is an odourless, colourless gas that is a by-product of combustion. The main sources in homes are smoking, fuel-burning appliances and infiltration of vehicle exhaust from attached garages or outside. The health effects from CO can be very serious.
When you breathe in carbon monoxide it binds with a protein in your blood called haemoglobin and reduces the ability of the blood to carry oxygen throughout the body. The symptoms of carbon monoxide poising get worse as CO levels and exposure time increase. At low levels, symptoms include headaches, tiredness, shortness of breath, and impaired motor functions. These symptoms sometimes feel like the flu. At high levels, or if people are exposed to low levels for long periods of time, people can experience dizziness, chest pain, tiredness, poor vision, and difficulty thinking. At very high levels, carbon monoxide can cause convulsions, coma, and even death.
Carbon monoxide levels in Canadian residences with properly functioning fuel-burning appliances are usually well below the limits recommended by Health Canada.
To protect you and your family from carbon monoxide follow these simple steps:
The Canada Mortgage and Housing Corporation (CMHC) also has information on carbon monoxide in the home and proper maintenance of fuel-burning appliances.
Health Canada's Residential Indoor Air Quality Guideline for carbon monoxide recommends maximum exposure limits of:
The short-term limit is meant to prevent the immediate health effects that may occur from exposure to CO for a limited period of time (e.g. 1 hour). The long-term exposure limit protects against health effects that may develop following extended exposure to CO (e.g. 24-hours).
Health Canada's recommended limits are set to protect sensitive individuals, such as those with pre-existing heart problems from extra stress on their hearts and lungs due to CO exposure. The most serious effects of carbon monoxide poisoning will occur at levels much higher than Health Canada's guidelines.
Installing a carbon monoxide detector with an audible alarm is a recommended safety precaution. Only those detectors bearing the Canadian Standards Association (CSA) certification mark should be purchased and these must always be installed and maintained in accordance with the manufacturer's instructions. For more information, consumers can visit Health Canada's Consumer Product Safety.
Carbon monoxide detectors are designed to prevent acute (immediate) carbon monoxide poisoning and are set to sound an alarm at levels significantly above Health Canada's exposure limits. Most detectors do not sound alarm until levels are above 70 ppm for 1-4 hours. Long-term exposure to CO levels below this level may affect health, especially for sensitive individuals, including the elderly and individuals with heart problems. A carbon monoxide detector can provide additional protection, but it is not a substitute for proper installation and maintenance of combustion appliances.
The Residential Indoor Air Quality Guidelines are Health Canada's official position on the health risks posed by an indoor air pollutant, based on a review of the best scientific information available. They summarize the known health effects, describe indoor sources and levels, and, provide a recommended exposure level below which health effects are unlikely to occur. The Guidelines are recommendations only and are not an enforceable standard under any regulation. They are meant to serve as a scientific basis for activities to reduce the risk from indoor contaminants. This could include the development of regulations or standards or the production of communication materials aimed at the general public.