Carbon Monoxide Poisoning

Environmental and Occupational Health Pearls: Carbon Monoxide Poisoning

A bi-monthly feature providing clinical information and resources from Public Health Ontario on matters relating to environmental and occupational health. This edition considers the most important questions about carbon monoxide poisoning.

What is carbon monoxide poisoning and how does it occur?

  • Carbon monoxide (CO) is a colourless, odourless and non-irritating toxic gas produced from combustion of carbon-based fuel.
  • Harmful exposures can occur from malfunctioning furnaces, heaters, stoves, car exhaust, generators, and fireplaces under poorly ventilated conditions.1,2
  • Poisonings occur most frequently in winter months.
  • Power outages are a period of particularly high risk when generators, barbecues, or other equipment meant to be used outdoors are brought into or close to indoor spaces.3

What are the symptoms?

Symptoms may include: headache, fatigue, nausea, and vertigo.1,2

How can family physicians respond?

CO poisoning is preventable. In the winter months, suspect CO as a possible cause in patients with non-specific symptoms. Winter may be a good time to remind patients of the dangers of CO, especially when power outages might be expected. Preventive measures include: maintenance of fuel-burning appliances, CO detectors, and keeping outdoor appliances well away (at least 20 feet) from the home.4,5

Where can I find more information?

  1. Wu PE, Juurlink DN. Carbon monoxide poisoning. CMAJ. 2014;186(8):611-611.
  2. Weaver LK. Carbon monoxide poisoning. N Engl J Med. 2009;360(12):1217-25.
  3. Iqbal S, Clower JH, Hernandez SA, Damon SA, Yip FY. A review of disaster-related carbon monoxide poisoning: surveillance, epidemiology, and opportunities for prevention. Am J Public Health. 2012;102(10):1957-63.
  4. Government of Canada. Prevent carbon monoxide poisoning [Internet]. Ottawa, ON: Government of Canada; 2017 [cited 2018 Jan 11]. Available from:
  5. Centers for Disease Control and Prevention. Carbon monoxide poisoning [Internet]. Atlanta, GA: US Department of Health and Human Services; 2017 [updated 2016 Nov 16; cited 2018 Jan 11]. Available from: