The effects of extreme heat and cold depend on a variety of factors. Experts say the 'comfort zone' is normally in the region of 16°C to 24°C.

As temperatures rise above about 25°C heat exhaustion starts. People suffer loss of concentration, increased accidents and loss of productivity. Symptoms include irritability, dizziness, headaches, nausea, fainting, extra strain on the heart and heat stroke.

At low temperatures shivering starts with loss of attention and fatigue. At very low temperatures symptoms include pain in extremities (ears, nose, fingers, toes) numbness, pins and needles, damage to blood vessels and frostbite.

When it is not possible or practicable to work within the comfort zone, the employer, in consultation with Usdaw reps, should carry out risk assessments and put other control measures in place.

For further information please contact the Health and Safety Department at Usdaw Central Office.