A Grimsby firm has been fined by a court after three workers in an asbestos decontamination unit suffered carbon monoxide poisoning.
The men, from Sheffield, were working in an asbestos enclosure on a demolition site in Huddersfield in November 2009.
A poorly-maintained gas boiler in the unit pumped out fumes that safety experts said could have proved fatal.
Huddersfield Magistrates' Court ordered Newlincs Services to pay a £5,000 fine.
Door seal damaged
The company must also pay £3,580 in costs after admitting breaching health and safety laws.
The court heard that after working in the asbestos enclosure for 90 minutes the men had to go through a three-stage decontamination process.
They began at the "dirty end", disposing of overalls, before entering a second stage where they showered and washed their respiratory equipment.
In the final "clean" section they changed into normal clothes.
But the Health and Safety Executive (HSE), prosecuting, told the court tests on the gas boiler used to provide hot water for the shower showed poor maintenance meant it was pumping out high levels of carbon monoxide.
In addition, a door seal and lock between the boiler compartment and "clean" sections of the unit were damaged, leading to poisonous gases being drawn into the clean end.
The three men, Richard McKearnen, 59, Tony Deakin, 50, and Paul Wainwright, 49, were "almost overcome" with dizziness and nausea, the HSE said.
'Nauseous and dizzy'
They were treated with high-flow oxygen therapy at Huddersfield Royal Infirmary and released later the same day.
Inspector David Stewart, of the HSE, said: "Carbon monoxide can be a silent killer in the home and, as this case demonstrates, also in the workplace.
"Even though these three men spent a relatively short time in the affected part of the decontamination unit, they were left seriously nauseous and dizzy.
"The consequences of longer exposure could have been fatal."