It is a fact that carbon monoxide is the leading cause of poisoning deaths. That is why it is important to maintain your homes equipment.
Any equipment in your home that burns fuel, has carbon monoxide combustion. And this includes anything such as a gas heater and a gas dryer, even a gas grill or stove and fireplace. Even when a appliance is running fine, there is still a small amount of carbon monoxide getting out. But that amount is usually carried out through the ventilation of that appliance.
Your gas furnace produces more carbon monoxide if it is dirty. And since carbon monoxide is odorless and colorless thats when people get harmed.
Routine maintenance helps to keep your gas heater running efficiently and safely. Have your furnace checked every year, and cleaned as well by a professional. Make sure also to change your filter on a regular basis. Always run your gas heater furnace according to the operating instructions. If your furnace has a pilot light and it goes out, turn the gas off right away.
The best safety feature is getting a CO detector installed in your home sleeping area.