Blocked chimneys and flues, soot build-up in boilers, and faulty gas appliances in caravans are just some of the hidden potential causes of fatalities from carbon monoxide poisoning.

The energy supplier, Southern Electric, is highlighting some of the most disturbing findings when its home services engineers have been called in to service gas boilers and advise on home appliance maintenance.

The campaign to warn Dorset people of the dangers of the so-called 'silent killer' coincides with the UK's second Carbon Monoxide Awareness Week, which was launched yesterday.

Although many people are aware of the need to regularly service their boiler, only around one in four homes have a gas boiler maintenance contract that ensure this happens, meaning many homeowners are totally unaware of the carbon monoxide danger they face from a faulty boiler or other faulty gas appliances in the home.

Southern Electric boiler expert Ian Batty said: "When we have visited homes for the first time in Dorset we've seen all manner of quite serious problems that the homeowner was completely unaware of, including obstructed flues, boiler burners working inefficiently, and significant amounts of soot build-up in and around boilers.

"Many people are also shocked to discover that other gas and fossil fuel appliances like cookers and fires can also produce carbon monoxide if they are not working properly."

National figures issued by the Council of Registered Gas Installers (CORGI) show that almost one-third of the incidents involving carbon monoxide poisoning are caused by faulty gas appliances.

"But the risk to individuals from carbon monoxide isn't just within their home," explained Ian Batty. "We frequently remind people to install carbon monoxide detectors in their caravans where they have fossil fuelled heating appliances of some kind.

"Another hidden danger is carbon monoxide leaking from neighbouring properties into your own. It's always worth talking to your neighbours about installing detectors if you are worried."

Carbon monoxide is known as the silent killer because it is completely odourless and cannot be seen. Around 50 people die every year as a result of CO poisoning.

It can happen within one to two hours, and even if it doesn't result in death it can cause serious illness and neurological damage.

The symptoms of CO poisoning range from tiredness and drowsiness to headaches and giddiness right through to vomiting, breathlessness, stomach pains and visual problems.

Southern Electric has issued a checklist for people to help prevent exposure to CO.

  • Have your gas appliances checked annually and serviced by a CORGI-registered installer.
  • Fit a CO detector with an audible alarm to back up your annual service.
  • If you live in tenanted accommodation, ensure your landlord carries out an annual gas safety check and maintains all gas appliances - they are legally obliged to.
  • Do not cover up vents or airbricks as these are for ventilation.
  • If you have a chimney or flue, ensure it is swept or cleaned regularly by a qualified firm.
  • Don't use unflued appliances such as paraffin heaters and cabinet heaters.
  • Make sure gas appliances in your caravans or second homes are regularly checked, and that you have CO detectors installed.
  • Find out how Southern Electric can protect your home on 0845 024 0525 or visit www.southern-electric.co.uk/foryourhome