Study into scale of havoc caused by silent killer

Specialists at three casualty units across the country, including St James's Hospital in Leeds, will assess the impact of carbon monoxide poisoning linked to faulty appliances both in the home and at work.

Around 50 people die annually from accidental carbon monoxide poisoning and there are an estimated 200 further casualties in England and Wales.

But experts believe the real level of harmful exposure is significantly higher as cases often mimic other conditions. One study found six per cent of applicances tested in 600 UK homes were producing dangerously high levels of the gas.

Tests on patients will begin shortly and the results of the investigation involving 900 people overall are likely to be published later this year.

Steve Bush, a consultant in emergency medicine at St James's, said signs of carbon monoxide poisoning were usually subtle and difficult to spot and there was evidence some people suffered symptoms for some time before seeking help.

"CO poisoning is recognised to be difficult to diagnose clinically and therefore is probably significantly underdiagnosed," he said.

"Severe poisoning is very uncommon which is one of the reasons why doctors are unused to making the diagnosis."

He said patients with headaches, chest pain, flu-like symptoms, seizures and with exacerbations of long-term respiratory conditions would be asked to enrol in the trial to investigate if carbon monoxide poisoning was the underlying cause.

A painless finger clip would used to measure the level of carbon monoxide in the bloodstream.

All patients will receive advice on the problem and those with raised levels will be referred to experts from their local Health Protection Unit which will investigate the cause of the poisoning to make sure no one else is affected.

The Health Protection Agency published new advice last year to help GPs and Accident and Emergency specialists to diagnose carbon monoxide poisoning in patients with symptoms which are also commonly associated with other ailments.

Carbon monoxide is colourless, odourless and tasteless. The gas reduces the oxygen-carrying capacity of blood and starves vital organs of oxygen.

Poisoning symptoms include headaches, nausea and vomiting, drowsiness, dizziness, chest pains, collapse and loss of consciousness.

Anyone with a fossil fuel or wood-burning appliance including boilers, heaters and cookers is advised to have them checked by a registered engineer each year, as well as fit carbon monoxide alarms, although surveys show more than eight in 10 households do not have audible alarms.

The gas is produced by incomplete combustion of fossil fuels – gas, oil, coal and wood used in boilers, engines, gas fires, water heaters and open fires.

Combustion problems are caused by poor installation or maintenance and poorly ventilated rooms.

Signs of problems include black sooty marks on bars above gas flames of gas fires, sooty marks on the wall around stoves, boilers or fires or smoke accumulating in rooms due to faulty flues.

Yellow instead of blue flames from gas appliances can be another sign that there may be a fault with an appliance although this does not apply to fuel-effect gas fires as they are designed to look like flames from a solid fuel appliance.

Some people can also be at risk if the gas leaks from faulty boilers in neighbouring homes.

Eleven people including two Thomas Cook employees are on trial in Corfu over the deaths of Christianne Shepherd, seven, and her brother Robert, six, from Horbury, near Wakefield, after fumes from a faulty boiler leaked into their holiday bungalow in October 2006.

The group are accused of manslaughter by negligence over the incident after carbon monoxide leaked into the room from a boiler outside. It later emerged a family staying in the bungalow the previous week had been hospitalised with symptoms of carbon monoxide poisoning.

Beautiful home proved deadly

Carbon monoxide poisoning is not a problem confined to run-down rented houses or cheap student digs.

City banker Nicolas Giauque lost his six-year-old daughter Elisabeth to the killer after the family moved into a beautiful home in Wimbledon in London in 2005.

She was taken to hospital after being found unconscious beside her bed. She died after initially being misdiagnosed with meningitis.

Doctors only realised she had carbon monoxide poisoning after her aunt and uncle, who had arrived at the rented home to grieve and were sleeping in her bedroom, were also admitted to hospital with symptoms caused by the gas from a faulty boiler.