The effects of extremes of temperature, and the controls

Working in a hot environment can cause:

• dehydration, as water is lost through sweating
• muscle cramps, from the loss of salt in sweat
• heat stress, when the core temperature (37 °C) can no longer be controlled and starts to rise, causing discomfort, lethargy, headaches and fainting
• heat exhaustion, which needs prompt action; heatstroke can develop rapidly and is not always preceded by recognised exhaustion
• heatstroke, when core temperature rises rapidly, causing hallucinations, coma and death

Other effects come from the source of the heat, such as skin burns or skin cancer from sunlight, or burns from radiant heat and contact with hot surfaces.

Working in a cold environment can cause:

• hypothermia, when the core temperature drops below 35 °C, causing shivering, mood swings, irrational behaviour, lethargy, drowsiness and death
• frostbite, when body tissues freeze, causing tissue damage and, in extreme cases, necrosis, gangrene and amputation
• slip hazards, in particular because floors turn icy
• freeze-burn injuries, from skin contact with very cold surfaces

The first course of action is to remove the need for workers to enter the extreme-temperature environment, for example by automating a process. Where that cannot be done, the environment may be regulated to reduce the extremes, such as heating a cold workplace to a more reasonable temperature. If neither is possible, other controls may be used.

Controls for a hot environment

• suitable ventilation or cooling selected for the temperature, humidity and task; moving very hot air is not necessarily effective cooling
• insulate heat sources, for example by lagging hot pipes
• shield heat sources to control radiant heat and prevent contact burns
• provide cool refuges where workers can escape the heat
• easy access to drinking water or isotonic drinks
• frequent breaks and job rotation
• suitable clothing for the hot environment, taking other workplace hazards into account

Controls for a cold environment

• prevent draughts, or protect workers from them
• shield or lag extremely cold surfaces
• provide warm refuges where workers can warm up
• provide PPE such as insulated jackets, trousers, boots and balaclavas
• frequent breaks and job rotation
• easy access to hot food and drinks
• scrape, salt or grit icy floors

In both types of environment, information, instruction, training and supervision should be provided so that workers understand the health consequences of the environment and the early warning signs of problems.

Summary notes for Element 8 · Cheat sheet · Glossary. A study aid, not published or endorsed by NEBOSH.