The University of Texas at Austin
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AHealthyHomeisinYourHands


Carbon Monoxide (CO)

What is Carbon Monoxide?

Carbon monoxide (CO) is a colorless, tasteless, practically odorless, highly-toxic gas that is the byproduct of incomplete combustion of hydrocarbons1,2. Worldwide, CO intoxication is one of the most common forms of poisoning, while in the United States it is the leading cause of poisoning death2.


What are the sources of CO in my home?

There are many sources of CO that affect the indoor environment. CO is formed during combustion reactions, and can come from auto emissions from attached garages, cooking and heating appliances that burn natural gas, coal, charcoal, wood, and other fuels, and tobacco smoke1,2. If the area in which these products are used is enclosed and poorly ventilated, CO can become concentrated and move into other living spaces. Improper ventilation includes the absence of proper ventilating devices (e.g., a vent hood that does not blow cooking fumes outside), as well as inefficiencies in existing ventilation (e.g., leaks or blockages in a chimney or furnace)1.


Are there any health effects from CO exposure?

CO poisoning occurs when the oxygen-carrying capacity of red blood cells is reduced. In red blood cells, an iron-containing protein called hemoglobin binds oxygen molecules and carries it from the lungs to the different tissues of the body4. When CO is inhaled, it binds rapidly to hemoglobin, displacing and preventing the binding of oxygen. In fact, the strength of the bond of CO to hemoglobin is 210 times greater than that of oxygen2. This results in less oxygen getting to body tissues, or tissue hypoxia.

In low exposures to CO, noticeable effects include dizziness, weakness, vomiting, disorientation, and visual disturbances5. Removing the individual from the area and administering oxygen are commonly used to treat these symptoms. In higher exposures, effects can include cardiac arrhythmia, respiratory failure, convulsions, brain damage, coma, and death. At extremely high or prolonged CO exposures, death can be immediate5.


How can I reduce my exposure?

The US Environmental Protection Agency recommends the following steps to reduce exposure to CO in your home1:

  • Keep gas appliances properly adjusted.
  • Consider purchasing a vented space heater when replacing an unvented one.
  • For kerosene space heaters, only use the fuel recommended by the manufacturer.
  • Install and use an exhaust fan vented to outdoors over gas stoves.
  • Open flues when fireplaces are in use.
  • Choose wood stoves that are properly sized for the space being heated and are certified to meet EPA emission standards. Make certain that doors on all wood stoves fit tightly.
  • Have a trained professional inspect, clean, and tune-up central heating systems (furnaces, flues, and chimneys) annually. Repair any leaks promptly.
  • Do not idle cars or other gas-powered vehicle or equipment inside an attached garage.


Where can I get more information?

For more information on carbon monoxide exposure and detection, contact:


References:

  1. Carbon monoxide: basic information. US Environmental Protection Agency; http://www.epa.gov/iaq/co.html, accessed April 2008.
  2. Prockop LD, Chichkpva RI. Carbon monoxide intoxication: an updated review. Journal of the Neurological Sciences 2007;262(1-2):122-130.
  3. Vreman HJ, Wong RJ, Stevenson DK, Smialek JE, Fowler DR, Li L, Vigorito RD, Zielke H. Concentration of carbon monoxide (CO) in postmortem human tissues: effect of environmental CO exposure. Journal of Forensic Science 2006;51(5):1182-1190.
  4. Hemoglobin. Encyclopedia Britannica Online; http://search.eb.com.ezproxy.lib.utexas.edu/eb/article-9039968, accessed April 2008.
  5. Raub JA, Mathieu-Nolf, M, Hampson, NB, Thom SR. Carbon monoxide poisoning: a public health perspective. Toxicology 2000;145(1):1-14.

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