THE threat of carbon monoxide poisoning hangs over every resident of Kirklees' 12,000 back-to-back houses.
That was the stark warning from a coroner investigating the death of 10-year-old Dominic Rodgers.
He was killed at his home in Spaines Road, Fartown, in February by carbon monoxide poisoning.
And West Yorkshire Coroner Roger Whittaker has urged people to carry out checks on their homes if needed.
With more than 12,000 back-to-back properties around Kirklees, experts fear there could be widespread danger from a build-up of lethal gases in the narrow passageways between the homes.
Two weeks ago, Mr Whittaker held an emergency resumption of the inquest into Dominic's death. Yesterday, he convened again to add further warnings.
"The nature of the problem is potentially enormous," said Mr Whittaker.
"There may be in the area of Kirklees 12,000 properties with passageways with similar potential problems.
"If that is so, it is likely that the problem throughout the country will be compounded hugely."
Investigations are ongoing to try to find out exactly what caused the build-up of carbon monoxide in the passageway next to Dominic's home.
The youngster died when emissions from a boiler flue sent gas into the passage which then seeped into his bedroom. Both the window and door to his small room were shut. He was discovered dead in bed on Thursday, February 12.
Experts have revealed low door lintels at either end of passageways could trap deadly gases from the flues.
An expert from the Health and Safety Executive spoke of the risks.
David Powell is a principal inspector for the HSE and deals with gas safety issues around the county.
He said the large stone lintels had the effect of trapping carbon monoxide if there is a boiler flue in the passageway.
Speaking after the inquest, Mr Powell said: "If a passageway has got lintels, and fumes can get between lintels there's a risk the fumes can travel up into the rest of the house."
Legislation came into force in 1990 to ensure flues were installed in well-ventilated spots.
Mr Powell said not every flue in every passageway was an immediate danger.
"But there are ones which are high risk."
Homeowners, landlords and tenants have been urged to get a Corgi-registered workman to check their boilers and flues.
Corgi can be contacted on 01256 372200.
The telephone number for British gas is 0845 9605040.
After the inquest, Dominic's uncle Jason Rodgers said he backed the coroner.
"Dominic's mum, Stacey, and the rest of the family would hate to see such a tragedy happen to anyone else in Huddersfield.
"The coroner is right; people must take action. The idea that 12,000 homes - and those are only the ones in Kirklees - could be dangerous is very frightening".
Huddersfield MP Barry Sheerman plans to take inmmediate action in the Commons.
He wants local authorities, gas safety experts and the public to work together to prevent future tragedies.
And he plans to table an emergency motion in the Commons seeking backing for the campaign.
"It is such an awful watse of life. There is a serious safety risk flagged up by this boy's tragic death and we must take action to prevent it happening again."