The Prevention of Motor Vehicle Exhaust Gas Poisoning

Release Date: October 16, 2002

Road Safety Fact Sheet
TP 2436 E

Motor vehicle exhaust gas contains carbon monoxide, which is a colourless, odourless gas that is produced by the burning of carbon-based materials such as coal, wood, paper, oil, gasoline, and cigarettes. When inhaled in sufficient quantities, carbon monoxide can cause symptoms that include sensitivity to light, headache, nausea, dizziness, and general disorientation. Visual perception and manual dexterity may also be affected, which can impair driving performance.

In 1971, the Government of Canada imposed limits on exhaust gas emissions at the tailpipe. The initial permissible limit for carbon monoxide was 24.1 g/km, which was lowered in 1975 and then again in 1987 to 2.1 g/km, where it remains today. As a result of emissions controls, motor vehicles were equipped with catalytic converters, which convert carbon monoxide to carbon dioxide, a harmless gas.

Although the reason for imposing emissions controls was to protect the environment, an unanticipated benefit has been a steady reduction in the number of deaths from accidental exhaust gas poisoning each year. From a high point of 162 deaths in 1973, accidental poisonings declined to 20 fatalities in 1999, the most recent year for which statistics are available. In the late 1990s, more stringent limits on pollutants other than carbon monoxide had the added benefit of further reducing the concentration of carbon monoxide in exhaust gas. Even stricter limits on these pollutants, which will come into full force in 2004, will reduce carbon monoxide emissions once again.

While the Government of Canada is pleased with this impressive reduction in the occurrence of accidental exhaust gas poisoning, it believes that, if everyone took the following simple precautions, deaths from unintentional poisoning could be eliminated altogether:

  • Have the exhaust system of your vehicle checked regularly for leaks that could allow exhaust gas to enter the interior. For non-commercial vehicles, once a year is recommended, perhaps at the time of your fall or winter servicing. For commercial vehicles, more frequent checks are advised.
  • Following a heavy snowfall, inspect the tailpipe to ensure that it is free of snow before starting the engine.
  • When idling a vehicle outdoors, keep a window partly open or a ventilation fan running.
  • Do not idle a vehicle in an unventilated garage or other confined space. Before starting the engine, open the garage door fully, then drive out as soon as possible to prevent a build-up of exhaust gas.
  • Never remain in a vehicle that is idling in an unventilated or confined space.
  • If your slide-in camper or recreational vehicle has a propane-fuelled generator or appliances, ensure that the vehicle is equipped with a carbon monoxide detector. Test the batteries in your carbon monoxide detector on a regular basis to ensure that it is working, and replace the batteries when necessary.
  • Carbon monoxide detectors designed to be used in the home are suitable for use only in a slide-in camper or recreational vehicle, but not in a passenger car, multipurpose passenger vehicle, sport utility vehicle, truck, or bus.

Related Facts:

  • Statistics indicate that more accidental poisonings occur in the winter months of December, January, and February than at any other time of the year.
  • Vehicle emissions testing programs show that older vehicles have higher emissions than newer models. A well-tuned engine has lower emissions, which is safer for you and protects the environment.
  • Catalytic converters convert the carbon monoxide in exhaust gas to carbon dioxide. Keep yours in good repair.
  • Manufacturers of slide-in campers and recreational vehicles who build their products in accordance with the requirements of the Canadian Standards Association (CSA) install carbon monoxide detectors in all slide-in campers and in all recreational vehicles that are equipped with, or designed for the future installation of, a propane-fuelled generator.

If you would like additional information, please contact our Information Centre at 1-800-333-0371, send us an e-mail at, or write to us at:

Road Safety and Motor Vehicle
Regulation Directorate
Transport Canada
Tower C, Place de Ville
330 Sparks Street
Ottawa, Ontario
K1A 0N5