How to manage heat stress and prevent heat stroke

With temperatures in up to 35 degrees Celsius this summer, employers and workers have to avoid heat exposure and manage heat stress.

Trade federation Cosatu made a call on employers (see below) regarding hot conditions at work.

The South African Weather Service said people in Johannesburg could expect an energy-sapping 39°C, with Pretoria even hotter at 41°C on some days.

The current record is 39°C in Pretoria and 38°C in Johannesburg, both set in 2015.

The Western Cape had temperatures up to 38°C, and the Northern Cape at Prieska 43°C in January 2016. South Africa had three heat waves in December 2015.

Health and safety consultant Chris Hattingh said workplaces must manage heat stress, in terms of the Environmental Regulations for Workplaces, regulation 2 (Government Notice R2281 of 16 October 1987).

Contrary to common perception, this regulation does not set a temperature at which people must be allowed to go home, but refers to a scientific calculation of temperature, radiant heat emitted by roofs and walls, and the cooling effect of air movement and humidity.

This calculation is referred to in the regulation as the WBGT index, and is not expressed in degrees centigrade.

When measured over a period of one hour, if the WBGT index is higher than 30, employers are required to take precautionary measures to prevent illness due to heat stress, including heat stroke.

Heat stroke may occur when the human body’s natural temperature regulation mechanisms fail to cool the body below 41 degrees Centigrade.

From around 39 degrees, the symptoms of heat exhaustion and heat stroke may vary from confusion, dark-coloured urine (a sign of dehydration), dizziness, fainting, fatigue, headache, muscle or abdominal cramps, nausea, vomiting, or diarrhoea.

Above 40 degrees, the symptoms may worsen and present an altered mental state or behaviour, alteration in sweating, flushed skin, rapid breathing and a racing heart rate.

Heat stress or heatstroke can generally be reversed with sufficient hydration, but if left untreated could result in coma and eventually death.

How to manage heat stress and prevent heat stroke

  • If practicable, take steps to reduce the WBGT index to below 30 by maintaining air-conditioning and extract ventilation.
  • Where the WBGT index cannot be reduced to below 30, and where hard manual labour is performed, ensure employees are certified medically fit by a registered medical practitioner or a registered nurse.
  • Allow new employees to become acclimatised before engaging in hard manual labour.
  • Train employees to take at least 600 millilitres of water every hour, and provide bottled water where possible.
  • Train employees in precautions against heatstroke.
  • Provide prompt first-aid treatment in the event of heatstroke.
  • Wear loose fitting, lightweight clothing.
  • Protect against sunburn.
  • Take extra precautions with certain medications.
  • Never leave children or pets in a parked car.
  • Take it easy during the hottest parts of the day, 12:00 to 15:00.
  • Take a quick swim, or shower, or dampen the skin.

Health and safety laws and regulations do not deal with feeling comfortable at work, but employers should consider the effect on production, and company reputation.

Accept that production would be slower during the warmer parts of the day. Consider combining tea and lunch breaks at the hottest part of the day, a practice in Europe and Latin America commonly referred to as siesta.

Labour call on employers to manage heat stress

The Congress of South African Trade Unions made this announcement; Cosatu is deeply worried by the recent heat wave that has engulfed the country and the impact it will have on workers, especially in the vulnerable sectors. We call on all employers to adhere to health and safety regulations and protect workers from dangers of dehydration and heat stress, especially those working in agriculture, construction, public works and those industries associated with warm and hot environments like mining, bakery etc.

The record temperatures that are being experienced and predicted all across the country risk many employees, in the above sectors ,suffering from dehydration and heat stress at work.

We call on employers to monitor a number of external factors to determine the risk of an employee being affected by heat stress.

They should also implement a heat plan once the temperatures rise to dangerous levels. Workers should be given regular breaks and should be provided adequate liquid like water.

When employees happen to work in hot conditions, employers should provide access to cool rest places to help them regulate their body temperature. This could be an air conditioned area indoors or a shaded area on an outdoor job site.

They should also follow weather alerts and also measure the heat and humidity in the workplace to ensure they have not gone above dangerous levels.

We also call on our affiliates to ensure that employers adhere to health and safety regulations. The department of Labour should also make sure that workers are not forced to work under dangerous conditions, where heat and humidity has gone above dangerous levels.

Supervisors and staff should be trained to spot the signs of heat stress. In addition a workplace process should be put in place that should be followed by employees to help a sick worker.

* Sources: News24. Cygma Sheq. Mayo Clinic USA. Cosatu.
• Chris Hattingh is a Mining Engineer and general manager of Cygma Sheq in Gauteng.

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4 thoughts on “How to manage heat stress and prevent heat stroke

  1. We supply simple and effective equipment for heat stress Managment.
    Proudly south African manufactured instrumentation.

  2. Chris,

    Good document and well done !!
    I am commenting out of the Mining industry and hence referral to the MHS Act and related DMR requirements in terms of Thermal stress. I am a little concern regarding some of comments. The MHS Act require the mining industry to compile a Mandatory COP on thermal stress for each operation (site specific) this include all surface operations. The guideline for this document is available on the DMR’S web site and might be a good idea to consult this document. I see you don’t mention the drafting / review of a risk assessment and hence my concern regarding the wearing of loose clothing as this may have a bigger risk in areas where moving machinery is used. My suggestion is that we rather refer to heat related symptoms (Heat cramps , Heat exhaustion ect as Heatstroke is the final step and specialised medical care is required at this stage) PS we measured 54 degrees (Dry bulb) yesterday Phalaborwa.



  3. Great article! Thank you.
    Perhaps one should see this as more general guidance, than industry specific such as mining. It applies to all industries and even can be applied at home. Given this time of year and the current heat waves we are experiencing in the country, it is good timing too.

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