The heat is on!

Heat stress, which refers to heat that is higher than the body can tolerate, generally occurs at temperatures of about 35°C in high humidity. But there are exceptions, and it is set to become a global obstacle of unexpected proportions.

Excess heat during work is an occupational health risk; it restricts workers’ physical functions and capabilities, work capacity and thus, productivity. In extreme cases it can lead to heatstroke, which can be fatal.

An increase in heat stress resulting from global warming is also projected to lead to global productivity losses equivalent to 80 million full-time jobs in the year 2030, according to a report from the International Labour Organization (ILO).

Projections based on a global temperature rise of 1,5°C by the end of this century suggest that in 2030, 2,2% of total working hours worldwide will be lost because of higher temperatures. This is equivalent to global economic losses of US$2 400 billion (more than R35 475 billion).

Moreover, the report cautions this is a conservative estimate because it assumes that the global mean temperature rise will not exceed 1,5°C. It also assumes that work in agriculture and construction – two of the sectors worst affected by heat stress – are carried out in the shade.

The ILO report, “Working on a warmer planet: The impact of heat stress on labour productivity and decent work”, draws on climate, physiological and employment data and presents estimates of the current and projected productivity losses at national, regional and global levels.

“The impact of heat stress on labour productivity is a serious consequence of climate change, which adds to other adverse impacts such as changing rain patterns, rising sea levels and loss of biodiversity,” says Catherine Saget, unit chief in the ILO’s research department and one of the main authors of the report.

But heat stress isn’t just a problem for the next decade, or one that is only around during the summer months as the Health and Safety Executive (HSE), Britain’s national regulator for workplace health and safety, points out. “In many jobs heat stress is an issue all year round (such as in bakeries, compressed air tunnels, foundries and smelting operations).”

Heat stress can affect individuals in different ways, and some people are more susceptible than others.

Typical symptoms include:

• An inability to concentrate;
• Muscle cramps;
• Heat rash;
• Severe thirst (a late symptom of heat stress);
• Fainting;
• Heat exhaustion – fatigue, giddiness, nausea, headache and moist skin; and
• Heatstroke – hot dry skin, confusion, convulsions and eventual loss of consciousness. This is the most severe disorder and can result in death if not detected at an early stage.
  
  

What should be done?

“Over time people adapt to hot conditions by sweating more and by changing their behaviour to try and cool down; for example, by removing clothing, taking cool drinks, fanning themselves, sitting in the shade or a cool area, and/or reducing their work rate,” HSE reports. “However, in many work situations such behavioural changes may not be possible.”

Where there is a possibility that heat stress will occur, employers need to carry out a risk assessment.

The major factors to consider, says HSE, are:

• Work rate – the harder someone works, the greater the amount of body heat generated;
• Working climate – this includes air temperature, humidity, air movement and effects of working near a heat source; and
• Employee clothing and respiratory protective equipment – this may impair the efficiency of sweating and other means of temperature regulation. The employee’s age, build and medical factors may also affect an individual’s tolerance.

HSE suggests these measures to reduce the risk:

• Control the temperature using engineering solutions, such as:
• Changing the processes;
• Using fans or air conditioning;
• Using physical barriers that reduce exposure to radiant heat.

Provide mechanical aids where possible to reduce the work rate. Regulate the length of exposure to hot environments by:

• Allowing employees to enter only when the temperature is below a set level or at cooler times of the day;
• Issuing work permits that specify how long employees should work in situations where there is a risk; and
• Providing periodic rest breaks and rest facilities in cooler conditions.

Prevent dehydration. Working in a hot environment causes sweating, which helps keep people cool but means that vital water is lost and must be replaced. Provide cool water in the workplace and encourage workers to drink it frequently in small amounts before, during (whenever possible) and after working.

Provide specialised personal protective clothing that incorporates, for example, personal cooling systems or breathable fabrics. This may help protect workers in certain hot environments. But employers should be cautious – protective clothing, or respiratory protective equipment, which is often provided to protect from a work hazard, could expose employees to heat stress as well.

Provide training for your workers (especially for new and young employees) informing them about the risks of heat stress associated with their work, what symptoms to look out for, safe working practices and emergency procedures.

Allow workers to acclimatise to their environment and identify which workers are acclimatised/assessed as fit to work in hot conditions.

Identify those employees who are more susceptible to heat stress either because of an illness/condition or medication that may encourage the early onset of heat stress (such as a heart condition). Advice from an occupational health professional or medical practitioner may be needed. Any risk assessment in place should already address risks to pregnant employees, but employers may choose to review it when an employee is pregnant, to help them decide if any more needs to be done to control the risks.

Monitor the health of workers at risk. Employers may need to monitor the health of workers exposed to the risk and should then seek advice from occupational health professionals with a good working knowledge of working in heat stress situations.

In summary, there are steps that can be taken to protect those at risk of heat stress, but everyone will have to do their part.

Saget warns: “In addition to the massive economic costs of heat stress, we can expect to see more inequality between low- and high-income countries and worsening working conditions for the most vulnerable, as well as displacement of people. To adapt to this new reality, appropriate measures by governments, employers and workers, focusing on protecting the most vulnerable, are urgently needed.”