Carbon Monoxide (CO) the Silent Killer

In Cornwall in February this year there were four suspected human CO fatalities, three in a caravan and one in a guest house.  Four dogs have also died in the same incidents.

As carbon monoxide incident investigators, we at CORGI see at first hand the devastation this causes to the family and friends of the deceased.  All of these incidents could have been avoided.

To protect you, your tenants or staff or guests in your establishments, then some simple actions can avoid exposing anyone to the dangers of CO.

It is important that gas appliances or other fossil fuel burning appliances (including barbeques) have been installed, serviced and adjusted correctly and that there is the correct volume of fresh air being provided. Then combustion of the gas will be satisfactory.

When the process of combustion is interrupted, such as when there is insufficient air or contaminated air, incomplete combustion will occur.  This results in carbon monoxide (CO) being formed.  Carbon monoxide is a toxic, colourless, odourless, tasteless, non-irritant gas.  CO is harmful to humans and animals.

CO has a great affinity with the body and when present it is more readily absorbed than oxygen which results in the starvation of oxygen to living tissue. This affects mental ability and incapacitates people without them knowing that there is a problem.  If a person affected by CO stands up, for example, then this exertion may cause them to collapse and be unable to escape the contaminated area.  The result is often fatal.

Signs to look for are staining around an appliance or fireplace and a loose yellow flame (but note that some gas fires are designed to have a ‘Decorative Flame’ which is yellow by design).  Medical signs are similar to colds and flu, headaches, dizzy spells and lethargy.  These symptoms are often ignored as the affected person simply thinks it’s a cold.

Servicing & safety checks

As a landlord you have a legal duty, under Regulation 36 of the gas regulations, to ensure that your gas appliances are safe and all appliances must be inspected for safety on an annual basis. In particular you must have your appliances serviced regularly by a qualified person.  Check the credentials of the person you employ and don’t take their word for it. We have all heard of instances of ‘I use Bob down the pub’ – this can lead to disaster!

Blocked ventilation openings

Never block ventilation openings. Ventilation is required for combustion, cooling and the flue (chimney).  If ventilation is too small or blocked in any way the combustion to an appliance will be affected and could result in a dangerous situation occurring.

Clean & clear boiler

Keep the area around a boiler clean and as dust free as possible.  Don’t store clothing or other items close to the boiler! Your instruction manual gives you more information on using your boiler and will often specify clearances where necessary.  If in doubt consult an expert.

CO detectors

Buy approved CO detectors – these look similar to a smoke alarm. These are battery or mains operated.  CO detectors are NOT an alternative to regular servicing and maintenance, but can save lives if something goes wrong.  There have been many incidents where CO has migrated from one property to another so you may not even have fossil fuel in your property but your neighbour may have therefore a CO detector is worthwhile.  Good detectors will have a life of five plus years.  It is best to buy a detector which has a built in battery. The sensors and batteries have a limited life span and the unit must be replaced when the limit is reached – if you just replace the batteries the unit may still not be operating correctly.  Use detectors which are manufactured to BS EN 50291 and display a BSI Kitemark.

Spot Detectors

DON’T use Spot Detectors.  These are small cards with a spot in the centre. The spot reacts with CO resulting in a colour change indicating its presence, however the draw backs are:

  1. Up to six month life span only
  2. No audible alarm so no use while asleep
  3. They can be affected by other household products


To summarise

  • correctly installed and maintained appliances will operate safely
  • using a CO detector will aid the safety of you and your guests
  • follow all the safety instructions with your equipment and use qualified persons to install and maintain your appliances
  • don’t forget cookers. Several incidents in the past have been as a result of using faulty cooking equipment as they tend not to be serviced as often as boilers.