Chimneys and Carbon Monoxide
Colorless, odorless, and potentially deadly, carbon monoxide emissions are not something you can afford to risk.
Each year, roughly 10,000 cases of carbon monoxide-related injuries get diagnosed. The symptoms of prolonged, low-level exposure are headaches, dizziness, nausea, fatigue, and depressions. In other words, it can feel just like a cold or flu, perhaps combined with the winter blues. This makes it likely that many such injuries never get properly diagnosed at all.
And that's just the injuries. Carbon monoxide can also kill.
A conservative estimate suggests that over 200 people in the United States die each year from carbon monoxide poisoning caused by problems in the venting of their heating system. A more liberal estimate by The Journal of the American Medical Association suggests 1,600 carbon monoxide related deaths from all causes combined.
Your fireplace burns gas or wood, resulting in heat plus hydrogen and carbon. The hydrogen combines with oxygen to form water. Improperly vented, the hydrogen can form water in your home, generating mold and mildew. But that danger isn't in the same league as what the carbon can do.
The carbon goes off in search of oxygen to which it can bind chemically. If there's plenty of airflow, that oxygen is easy to find. One carbon atom binds to two oxygen atoms producing CO2 (carbon dioxide). While you can't breathe carbon dioxide, it doesn't harm you to have some hanging about. In fact, you're breathing out carbon dioxide right now.
But if the air flow gets restricted, there isn't as much available oxygen for the carbon to bind to. The carbon makes the best of a bad job. If it can't bind to two oxygen atoms, it can at least grab one. That produces CO (carbon monoxide).
You need oxygen to live. You breathe the oxygen through your nose and mouth into your lungs. Your lungs put the oxygen into your bloodstream so it can be distributed. But what if there's carbon monoxide there as well? Your blood (specifically the protein hemoglobin) will preferentially latch onto the carbon monoxide, ignoring the available oxygen. In effect, your cells will start to suffocate. This means the air doesn't have to be filled with carbon monoxide before it starts to affect you. There just has to be enough of it around for your blood to choose it instead of the copiously available oxygen that surrounds it.
Make sure your chimney is well vented to avoid this. Have it checked by a professional. Place a simple carbon monoxide detector next to the unit to be safe. And see your physician about persistent cold and flu-like symptoms, chronic fatigue, and depression.
Hopefully this guide has served as a good introduction to chimneys and carbon monoxide. If you would like to learn more about chinmeys, venting, and carbon monoxide, you may want to browse the extensive information listed on the resources below.
Chimney Safety Institute of America: Non profit organization dedicated to education of the public and chimney professionals on chimney safety and venting issues.
Wood Smoke: Article from the EPA on the affects of smoke from a wood burning fire.
National Chimney Sweep Guild: Industry associatition for chinmey sweep professional. View the member directory to locate a chimney cleaning professional.