March 10, 2014: Does CO poisoning occur only during winter?

This Question of the Week was prepared by Bhavana C. Anand, MD, MPH, an occupational medicine resident from Meharry who is spending time with Dr. Benitez.  Please take a few minutes to complete the survey at the end of the question, as it is part of her toxicology project.


The answer is No!  Carbon Monoxide (CO) poisoning occurs throughout the year.

Over 250 calls related to CO exposure were received by Tennessee Poison Center during 2013. Peak calling rates were in winter and fall.

CO can be produced anytime by burning fuels and inadequate ventilation. Some household examples are furnaces, ovens, idling cars with improper ventilation and water heaters.  As CO is a colorless and odorless gas, people don’t recognize the exposure.




During winter, heaters are put back into use, and many people have not done preventive maintenance on their furnaces.  They are unaware if the furnaces are adequately functioning or if there is a malfunction with improper ventilation that can lead to CO accumulation inside the dwelling. Water heaters are potentially dangerous when malfunctioning and when used for indoor swimming pools, may again cause CO exposure. . Use of generators indoors or in semi-enclosed areas or fireplaces with improper venting can cause lethal concentrations of CO.

As spring arrives, people get their lawn mowers, tillers, leaf blowers and other gasoline powered machinery out of hibernation. Since it is still cold outside, “quick checks” are sometimes done in a closed or semi-enclosed garage which can be dangerous. Sporadic episodes of cold weather in spring make people reach for their heat sources to warm up the house. This can lead to dangerously high levels of CO in the working area or house if not adequately ventilated. Spring storms bring power outages enticing some people to bring gas powered generators indoors without properly venting them.

In summer, we are out of the cold weather finally and want to be outside. How can being outside predispose you to CO poisoning? It is counter intuitive but some of the fun activities like camping, boating and water skiing can be dangerous. Boats can cause dangerously high levels of Carboxy hemoglobin (COHB) in just minutes. Some boats have generators or motors venting in the rear of the boat; this is a typical spot to place platforms or swim decks. Children who play on these decks or swim under the platforms can be exposed to very high levels of CO. People camping in trailers and tents often cook inside their shelter or use generators to warm these units exposing them to CO.

In fall, cooler weather and cold snaps occur which leads to the same scenario as spring. Leaf blowing and yard maintenance using gas powered units may cause CO poisoning if improperly tested, used, or vented.

All CO accidents and deaths are preventable! CO poisoning can occur throughout the year . . .  we should educate our patients at every opportunity. Remind them that ANYTHING that burns a fuel can produce CO gas and may cause poisoning.

Links on CO:

This survey is a residency project for Dr. Anand to assess the usefulness of this article. It will take up to 1 minute to complete it. Please click on link or copy URL and answer it as soon as possible. Thank you!

Thank you for completing it!

Bhavana. C. Anand MD,MPH 

Occupational Medicine Resident

Meharry Medical College

Department of Family & Community Medicine

Division of Occupational Medicine


I am interested in any questions you would like answered in the Question of the Week.  Please email me with any suggestion at


Donna Seger, MD

Medical Director

Tennessee Poison Center

Poison Help Hotline: 1-800-222-1222