CARBON MONOXIDE

What is carbon monoxide?
Carbon monoxide (CO) is odorless, colorless, and tasteless. When it is breathed into your body, it combines with your blood and prevents it from absorbing oxygen. It's responsible for half of the fatal poisonings in the U.S. each year.

Where does it come from?
Carbon monoxide is produced by incomplete combustion of fuels such as oil, propane, coal, wood, natural gas, gasoline, diesel fuel, charcoal, and kerosene. Faulty or inadequately vented vehicles and appliances that use these fuels -- furnaces, fireplaces, wood stoves, charcoal grills, kerosene heaters, gasoline-powered vehicles, lawn mowers, and snow blowers -- can produce deadly amounts of carbon monoxide.

What are the medical effects of carbon monoxide and how do I recognize them?
Carbon monoxide (CO) inhibits the blood's ability to carry oxygen to body tissues including vital organs such as the heart and brain. When CO is inhaled, it combines with the oxygen carrying hemoglobin of the blood to form carboxyhemoglobin (COHb). Once COHb is formed, that hemoglobin is no longer available for transporting oxygen. How quickly the carboxyhemoglobin builds up is a factor of the concentration of the gas being inhaled, as measured in parts per million (PPM), and the duration of the exposure. Compounding the effects of the exposure is the long half-life of carboxyhemoglobin in the blood. Half-life is a measure of how quickly levels return to normal. The half-life of carboxyhemoglobin is approximately 5 hours. This means that for a given exposure level, it will take about 5 hours for the level of carboxyhemoglobin in the blood to drop to half its current level after the exposure is terminated.

The following table describes the symptoms associated with a given concentration of COHb:



COHb     Symptoms and Medical Consequences





10%      No symptoms. (Heavy smokers can have as much as 9% COHb.)





15%      Mild headache.





25%      Nausea and serious headache.  Fairly quick recovery after


         treatment with oxygen and/or fresh air.





30%      Symptoms intensify.  Potential for long term effects especially


         in the case of infants, children, the elderly, victims of 


         heart disease and pregnant women.





45%      Unconsciousness.





50%+     Death.

Since one can't easily measure COHb levels outside of a medical environment, CO toxicity levels are usually expressed in airborne concentration levels of parts per million (PPM) and duration of exposure. Expressed in this way, symptoms of exposure can be stated as follows:



    PPM CO      Time        Symptoms





    35 PPM      8 hours     Maximum exposure allowed by OSHA in the


                            workplace over an eight hour period.





   200 PPM    2-3 hours     Mild headache, fatigue, nausea and dizziness.





   400 PPM    1-2 hours     Serious headache, other symptoms intensify.


                            This level is life threatening after 3 hours.





   800 PPM    45 minutes    Dizziness, nausea and convulsions.


                            Unconscious within 2 hours.


                            Continued exposure: Death within 2-3 hours.





  1600 PPM    20 minutes    Headache, dizziness and nausea.


                            Continued exposure: Death within 1 hour.





  3200 PPM   5-10 minutes   Headache, dizziness and nausea.


                            Continued exposure: Death within 1 hour.





  6400 PPM   1-2 minutes    Headache, dizziness and nausea.


                            Continued exposure: Death within 25-30 minutes.





12,800 PPM   1-3 minutes    Death.

As can be seen from the information above, the symptoms vary widely based on exposure level, duration and the general health and age on an individual. Also note the one recurrent theme that is most significant in the recognition of carbon monoxide poisoning is headache, dizziness and nausea. These "flu like" symptoms are often mistaken for a real case of the flu and can result in delayed or misdiagnosed treatment. When experienced in conjunction with the sounding of a carbon monoxide detector these symptoms are the best indicator that a potentially serious buildup of carbon monoxide exists.

Symptoms and Signs
Carbon Monoxide is especially dangerous for children, older adults and people who have heart or respiratory conditions. It can cause headaches, nausea, fatigue, dizziness, drowsiness, and burning eyes. Prolonged exposure causes more severe symptoms, including confusion, disorientation, convulsions, and unconsciousness. In very severe cases, carbon monoxide poisoning can be fatal.

If anyone is experiencing these symptoms, get immediate medical help. Call 911 or your local Emergency Medical Service.

Here are some other warning signs:

Stale or stuffy air
Excessive moisture on windows and walls
Soot buildup around appliance vents
Abnormal gas flame at appliance

What can I do to prevent carbon monoxide poisoning?
The Hamilton Fire Department recommends annual inspections for furnaces, water heaters, and equipment, including venting and chimneys. Here are some additional steps you can take to reduce the chance that carbon monoxide might build to harmful levels:

Purchase and install one or more Carbon Monoxide Detectors in your home
Regularly check the flame on natural gas appliances. It should be blue. If it's yellow, its a sign that the fuel isn't burning completely and could produce carbon monoxide. Turn the appliance off and call us or your appliance repair service.
Keep flues and chimneys clean and free of debris. To test for blocked chimneys or vents leading from your furnace, turn on your furnace for 10 minutes and turn it off. Hold your hand under the vent hood (CAUTION: DO NOT TOUCH). If hot air comes out, call us or your furnace service for an inspection.
Repair rusted or pitted flue pipes leading from your furnace and water heater to the chimney.
Do not block the furnace air intake. If your furnace is housed in a small room, provide adequate fresh air through louvered doors or other fresh-air grills.
Never use a gas range or unvented space heater to heat your home.
Keep your garage door open whenever a vehicle inside it is idling.
Start lawn mowers and snow blowers outside, rather than inside the garage.
Never use a barbecue grill inside your home, an enclosed porch, or your garage.

If your carbon monoxide detector sounds an alarm, do not panic. Follow these simple steps:

Check to see if anyone is experiencing these symptoms: nausea, burning eyes, light-headedness or dizziness, unconsciousness. If you notice these symptoms, get immediate medical help. Call 911 or your local Emergency Medical Service. Then call your gas utility or another qualified contractor to have your appliances checked. There may be a charge for this service.
If there is no emergency, evaluate the situation.
Open doors and windows to vent your home.
Turn furnace thermostat to its lowest setting.
Turn off all unvented appliances (range, auxiliary heater).
Turn gas or oil water heater to its lowest setting.
Check flues for obstructions.
Check for soot at the base of the water heater and furnace.
Check for vehicle or small engine operating in attached garage or basement.
Check the detector and other conditions: Is it located near the kitchen, bathroom, or other areas where unvented appliances, chemicals, or humidity can cause the alarm to sound? Is it located near where people were smoking? Were cleaning products recently used nearby? Did the alarm sound when the weather included prolonged rain or dense fog?
If you can't find a problem and no one is ill, call a carbon monoxide professional to help you evaluate your situation.

[Back to the HFD Home Page] [Back to the Safety Info. Page]