straight forward health and safty advice 
Gas can come from a number of sources; however the risks of explosion, poisoning, etc. are similar for all of them The word 'gas' in this section relates to the use of gas within the workplace, as well as in the home. It is commonly used in the workplace for processing products, heating the work space and for hot water supplies, as well as cooking. Natural gas (mostly methane) is distributed to domestic, commercial and industrial consumers through an onshore network of buried pipes; whereas LPG is either supplied by a storage tank, or by small cylinders. Liquefied petroleum gas (LPG) is supplied in red (propane) and blue (butane), cylinders and can be extremely dangerous if it is not handled correctly. Butane does not function properly when the air temperature is at freezing point or below, as it has a boiling point of -2 degrees centigrade. LPG is heavier than air and any leakage will accumulate at low levels, for this reason, fuel gases and other flammable materials must be stored separately. Cylinders should preferably be stored outside in a locked cage, with prominent ‘No Smoking’ notices displayed. When methane, propane, LPG and other gases do not burn properly, or are used in an area without adequate ventilation, excess carbon monoxide (CO) is produced, which can kill within hours if inhaled. You can't see it, taste it or smell it, but CO can kill quickly without warning. For this reason, a carbon monoxide detector and alarm system must be installed anywhere gas is burned. Symptoms of carbon monoxide poisoning include tiredness, drowsiness, headaches, nausea and chest and stomach pains. To ensure their safe operation, gas appliances must be regularly checked and maintained, in line with the manufacturers' instructions. Gas engineers that are competent to install and maintain gas systems and appliances are members of the Gas Safe Register, and carry a registration card. Smell Gas? To report a gas or carbon monoxide emergency call the National Gas Emergency Service - 24 hours a day - on 0800 111 999.