Chesterfield Borough Council has been fined after carbon monoxide (CO) fed back into one of its properties, putting the tenant at risk of poisoning.

A contractor carrying out roof work on the house in Stand Road, Newbold, on behalf of the council advised them the chimney stack was leaning and in danger of collapsing so the council arranged for it to be removed and capped.

However, the stack contained the flue for a gas fire and gas-fired back boiler and the removal and capping of the chimney stack meant there was no direct route for CO and combustion products from the fire and boiler to be safely vented to open air.

Instead the dangerous gas fed back into the house via the fire into the lounge and attic and outside through the eaves.

This was only discovered around six weeks later when the council was carrying out the annual gas safety check on the property.

An investigation into the incident by the Health and Safety Executive (HSE) found the council was aware the property contained working gas appliances as they were listed on two separate databases, but failed to check them.

At no point was the presence of the live gas appliances mentioned to the roofing contractor. The chimneystack was removed and the subsequent invoice detailing the work was paid by the council without question.

Chesterfield Borough Council pleaded guilty to breaching Section 3(1) of the Health and Safety at Work etc Act 1974 for failing to maintain its property in such a way that the tenant was not exposed to the risks associated with CO. The council was fined £18,000 and ordered it to pay costs of £7,534 by Chesterfield Magistrates' Court on 13 December.

HSE inspector Scott Wynne said: "It was pure luck that the tenant did not suffer any serious effects of carbon monoxide poisoning. This was probably due in part to the particularly warm weather at that time of year, which meant the tenant often had the windows open and only used the gas boiler for hot water.

"Chesterfield Borough Council was in a position of trust. It had a duty of care to its tenant but because it did not properly consult its own records or do any kind of follow-up checks once the stack had been removed, it failed in that duty.

"It was also extremely fortunate that the annual safety inspection was due at that time. If it had been due later in the year the tenant may not have survived to tell the tale."