Hydration (maintaining correct levels of body fluids) is the MOST IMPORTANT personal factor for protection against heat illness.
The body relies on sweating to cool down and poor hydration or low levels of body fluids reduces of stops sweating and the body heats up and workers suffer from heat illness like heat exhaustion or heat strike.
The fluid intake required to maintain hydration is determined by the sweat rate which in turn is determined by the work rate and the conditions. Sweat rates vary considerably and increase with acclimatisation. The recommended fluid intakes for the average acclimatised worker are given in the TWL work zone table.
It is very important to encourage exposed workers to:
- Come to work well hydrated and drink at least 1 litre of water before work each day;
- Drink regularly during the day at least 2 Litres of water every 2-3 hours;
- Self-assess hydration using coloured urine charts;
- Carry a large water container with them of at least 2 litres to drink within 2-3 hours;
- Ensure replacement of electrolytes by adding a little extra salt to meals or selecting correct electrolyte drinks.
Choice of Fluid Replacement Drinks
Replacement of the fluid lost in sweat requires intake of adequate quantities of water and salt. Drinking at mealtimes replaces both and is essential. Remember to encourage workers to:
- Add a little extra salt to their meals during hot weather, salt tablets should not be taken;
- Drink water with meals;
- Limit consumption of soft drinks as the sugar content is high;
- Limit consumption of caffeinated drinks (coffee, tea, cola) and ‘energy drinks’, as the caffeine may reduce fluid retention.
If workers are sweating heavily between meals an electrolyte replacement drink is recommended. Replacing salt as it is lost helps the body absorb and retain the water consumed:
- Sports drinks are high in sugar and often quite acid which can damage teeth. They are not designed for prolonged consumption at work;
- For prolonged consumption a fluid with 4% or less sugar is recommended. Appropriate products designed for industrial use are available commercially;
- The suggested schedule is to drink the electrolyte replacement fluid at every second drink (i.e. one for one with water);
- For diabetics or those on sugar restricted diets medical advice is required on the preferred fluids for rehydration.