What is CO & why does it need to be monitored?

Carbon Monoxide is an invisible, odourless, tasteless and extremely toxic gas that, if inhaled, can cause serious ill effects - justifying its name as 'The Silent Killer'. CO is readily absorbed by haemoglobin in the blood - approximately 240 times more efficiently than oxygen. This causes serious damage to the heart and brain from oxygen starvation.

How is CO produced?

Carbon Monoxide originates from the combustion of any
fossil fuel - coal, bottled and natural gas, paraffin, wood, petrol, diesel, charcoal etc.

What are the main sources of CO?

All Fossil fuel burning appliances produce CO, this is normally vented through flues and chimneys to the outside atmosphere. However, if the process is not entirely efficient, CO can build up to dangerous levels. Examples of possible causes are:

Poorly connected, blocked, cracked or corroded flue pipe/vent

Flue pipes/vents are designed to allow the CO produced by the appliance to vent to the outside atmosphere. If the flue is not operating correctly or is damaged, CO may leak into the property. Even if there is an annual check on the appliance/s, flues and vents remain a potential hazard.

Back drafting

Building Regulation requirements for energy efficient homes and a greater emphasis on air extraction e.g. bathroom and kitchen fans, means there is a risk of creating negative air pressure. This can cause reverse airflow through appliances resulting in dangerous levels of CO being drawn back into the property.

Cracked heat exchanger on gas central heating system

This will result in a large amount of CO leakage and is therefore a particularly dangerous possibility.

Appliances without flues

Some fuel burning appliances do not have flues. Portable heaters, cooking rings and grills are particularly vulnerable as are old appliances. Whether burning liquid gas, paraffin, natural gas or wood, each are capable of emitting dangerous levels of CO.

What are the effects of CO poisoning?

Carbon Monoxide poisoning can have a very serious, even fatal, effect on the body. Unfortunately, most people are unaware that a relatively low level of CO exposure for a prolonged period can have the same effect as a high level of CO exposure for a short period. A major problem is that the symptoms of CO poisoning can easily be confused with other common illnesses - such as cold and flu. The table below details the effects of cumulative CO exposure.

Is there any evidence of CO in the home?

In January 2006, the Bartlett School of Graduate Studies at the University College London, in partnership with Guys & St. Thomas Hospital, carried out a survey into indoor CO exposure. It was found that 18% of the homes monitored had CO levels that exceeded the World Health Organisation (W.H.O.) guidelines.