Carbon monoxide can spill from vent connections in poorly maintained or blocked chimneys. If the flue liner is cracked or deteriorated, carbon monoxide can seep through the liner and into the house - slowly creeping up to dangerous levels. If a nest or other material restrict or block the flue of the chimney, carbon monoxide will spill back into the house. Improperly sized flues connected to new, high-efficiency furnaces and water heaters can also contribute to carbon monoxide spillage. Many new furnaces and water heaters are installed using the existing chimneys which may be the wrong size to allow the furnace to vent properly.
Carbon monoxide inhibits the blood's capacity to carry oxygen.
Hemoglobin readily accepts carbon monoxide - even over the life giving oxygen atoms, forming a toxic compound known as carboxyhemoglobin. By replacing oxygen with carbon monoxide in our blood, our bodies poison themselves by cutting off the needed oxygen to our organs and cells, causing various amounts of damage, depending on exposure. Unconscious within 2 hours. Death within 1 hour. Death within 1 hour.