The leading cause of fires is poorly maintained and dirty chimneys and chimney flues, a cause which in most cases could be eliminated with an annual fireplace cleaning done by a qualified chimney sweep company. The National Fire Protections Association Standard states that chimneys be inspected on a yearly basis for any structural faults, also missing or poorly fitting chimney caps may lead to birds building nests in your chimney or other debris like branches and leaves accumulating there. These are leading causes of fire and smoke downdraft problems. Furnace chimneys also require inspection and cleaning, since dirty or blocked furnace chimneys may result in fire or in a backup of exhaust gases like carbon monoxide or carbon dioxide which may lead to poisoning and even death.The removal of creosote, dirt, and debris from the chimney, chimney flue, chimney caps, and firebox. Creosote is the leading cause of fireplace fires.