Clearing the ashes from your woodburner or open fire is just part of the routine. Many of us will use a metal bucket to put them in as it’s not uncommon for there to be the odd hot ember.
But you should ALWAYS put the bucket outside. Even a small amount of glowing embers will give off poisonous Carbon Monoxide gas. This gas is harmless outside but, can be really dangerous in the house.
Glowing embers hidden in the ash can last a surprisingly long time and it’s not uncommon to find them the next day. Ash is a great insulator and a good coating also excludes oxygen. This allows embers to remain live long after all the flame and heat has died away. Poisonous gasses can build up, making us unwell or worse.
It also makes sense to leave any ashes in the bucket for some time, or to dispose of them in such a way as to present no fire risk: Last year we heard the disturbing story of a sweep’s customer in Lincolnshire who had just moved house. Emptying the ashes from the solid fuel AGA onto the border in the garden seemed to present no risk. However, there was a particularly strong wind which fanned some still glowing embers. These set fire to a wooden larch lap fence. By the time the owner noticed, the fire had engulfed part of his garage. He lost two valuable motorbikes and his beautiful old Jaguar. He was slightly injured rescuing a third bike.