Dehydration

Dehydration can seriously affect an employee's ability to function safely when under thermal stress. Dehydration effects can be minimised in heat stress situations by encouraging employees to frequently drink cool water (rather than tea, coffee or carbonated drinks) in small volumes to compensate for losses due to sweating. Also you should be aware that thirst is not a good indicator of dehydration as if you are thirsty you are already starting to suffer from the effects of dehydration.

What this means is that when working hard in heat stress conditions employees should consume around 250 ml (half a pint) every 15 minutes or 500 ml (a pint) every 30 minutes. However this approach may not be practical due to the nature of the task eg wearing PPE that restricts the ability to drink or working in industries where hygiene requirements prevent the consumption of food or drink. In these circumstances an alternative approach is drinking 500 ml of water per hour before work commences and encouraging the drinking of 500 ml of water during their rest periods.

This may meet their water demands during the work period but if water loss is significantly greater, then water intake should increase proportionately. Also even if workers replenish the lost sweat with equal amounts of water, they may still be susceptible to dehydration due to salt losses caused by excessive sweating. This means that before they start work they should ensure that they are adequately hydrated.