What are the dangers associated with fumes from oil furnaces?

Deadly. If a furnace is not properly vented, or in the case of a malfunction, the fumes can be deadly. Fumes from burning hydrocarbons results in the emission of carbon monoxide gas. This gas has a very strong attraction to hemoglobin, the molecule that carries oxygen to our body. This strong bond between the carbon monoxide and hemoglobin prevents oxygen from being taken up and distributed to the body.