Carbon Monoxide is known as the "silent killer".  Every year approximately the equivalent of one person every two weeks dies from carbon monoxide poisoning in the UK.  

There are a number of possible causes of Carbon Monoxide;

• Incorrect installation of a gas appliance
• Incorrect service (if any) of a gas appliance
• Blocked flue
• Blocked chimney

The problem with Carbon Monoxide is that you can't see, smell or taste it.  There are however some symptoms you may feel when using the appliance;

• Drowsiness/weakness
• Headaches
• Nausea
• Pain in the chest area

Other danger signs you might notice are;

• Sooting on the gas appliance, especially around the top
• Gas appliance has a yellow/orange lazy flame 
• Excessive condensation in the room where the gas appliance is

If you suspect there may be Carbon Monoxide, switch off your appliance and have it checked by a CORGI registered gas installer.  If you feel unwell contact your Doctor.  

Better still, make sure your gas appliances are serviced annually by a CORGI registered installer and be wary of second hand gas appliances.  If you live in rented accommodation, your Landlord is legally obliged to have all gas appliances serviced annually and to show you written proof ( Gas Safety Certificate ) upon request.