Heat at work: 6 tips for productive work in high temperatures

Temperatures are currently tropical in many regions, and there's no improvement in sight. Such extreme heat events are likely to become more frequent in the future. Companies therefore have good reason to be concerned about the increasingly hot summers.

A 2021 report by the rating agency Moody's warned that climate change-induced heat stress was becoming a real risk for a vast number of industries . The report also stated that extreme temperatures pose a threat to businesses not only due to rising cooling costs and changing demand, but also due to their negative impacts on human health. Indeed, heatwaves can cause exhaustion, cramps, deteriorating mental health, complications in people with diabetes, and even strokes. What makes this even more serious is that the risk affects all segments of the population—including your company's workforce.

In addition to the direct health costs caused by heatwaves, the World Health Organization considers productivity loss to be one of the most serious economic consequences. It is estimated that approximately 2 percent of total working time is lost worldwide each year due to heat stress in the workplace.

Keeping a cool head is difficult in extreme heat. But insights from the healthcare sector offer valuable approaches for how employers can effectively protect their employees. From my experience as a physician in an international management consultancy, I've compiled six new and proven strategies:

First of all, employers should educate their employees about what heat stress is, how it affects their health and safety, and how it can be avoided.

In any warm environment, the human body relies on getting rid of excess heat to maintain a healthy body temperature. This occurs naturally through sweating and increased blood flow to the skin. If this doesn't happen quickly enough, body temperature rises, and heat stress can occur.

Symptoms of heat stress include thirst, irritability, rash, and exhaustion. In severe cases, heat stroke can occur, which manifests as brain dysfunction such as slurred speech, confusion, or disorientation—in extreme cases, even coma. Heat stress also impairs fine motor skills and makes it difficult to process task-relevant information. Even simple tasks like typing on a computer can become challenging.

During heat waves, workers can experience two types of heat-related illness: "heat illness," which is caused by physical activity, and "environmental heat illness," which is triggered by environmental conditions such as heat and humidity. The risk of environmental heat illness is particularly high in urban heat islands, as temperatures in a city are significantly higher than in surrounding rural areas.

Ultimately, heat stress can lead to illness, hospitalization, and even death. Given this threat, employers should be proactive and integrate an effective heat-related illness prevention program into their company's overall health and safety program.

During the first few days of a heat wave, employers should remind their employees to drink water, take frequent breaks, and monitor for heat-related symptoms.

Various factors influence the level of heat stress in the workplace. The following factors should be considered in the assessment:

• the working environment (including conditions such as humidity, sunlight and air flow)

• the activity (for example, whether the tasks require physical activity or the wearing of protective clothing)

• the individual employees (general individual risk factors such as age, pre-existing conditions and lifestyle)

The most accurate method for measuring the effects of ambient heat on body temperature is a Wet Bulb Globe Temperature (WBGT) meter, which combines temperature, humidity, sunlight, and air movement into a single measurement. The U.S. Occupational Safety and Health Administration (OSHA) provides guidance on its use and interpretation . A heat index, which refers only to temperature and humidity, can provide useful surrogate data in certain circumstances.

Workplace physical activity can be estimated using metabolic heat and workload tables, which classify workloads from light (sitting or standing) to very heavy (intense physical activity). Employers should also consider whether work clothing increases risk and identify occupations in hot environments such as firefighting, agriculture, construction, mining, and factory work.

Individual factors can also indicate specific risks. Those at particular risk include those over 65, pregnant women, and those suffering from certain types of heart disease, high blood pressure, obesity, or diabetes, or those taking certain medications. Gender differences must also be considered. The National Institute for Occupational Safety and Health (NIOSH) reports several studies showing that women tolerate heat less well than men.

A consistent indoor temperature is important for well-being and productivity. If it's too warm, employees feel tired or suffer from mood swings. If it's too cold, attention may wander, and they may feel restless or distracted.

Even small deviations can cause stress, impair performance, and even jeopardize safety. Workers already under pressure are less able to tolerate additional stress. Therefore, maintaining a comfortable temperature is especially important for high-stress workplaces and during times when pressure is particularly high and teams need to respond quickly.

The recommended temperature ranges meet the needs of an estimated 80 percent of people. However, some may still feel uncomfortable. Temperature needs and preferences vary widely, and there is no single temperature that can satisfy everyone. Therefore, additional measures may be necessary.

Differences may be due, among other things, to the fact that the regulations are based on standard values ​​for men. Women, however, prefer a higher ambient temperature at home and at work. The values ​​appropriate for men may even impair their performance.

Women are more vulnerable to high temperatures during heat waves. This vulnerability increases after menopause, when the lack of estrogen production makes it difficult to adapt to sudden temperature increases.

Well-being in the workplace depends not only on temperature, but also on other factors such as physical activity, sunlight, and air circulation. Companies can also address this: Desk fans or airy workspaces help employees who suffer from hot flashes. Furthermore, the work environment can be improved by adjusting workloads and working hours. For example, employers could shift activities to cooler times of the day or introduce shorter shifts with more frequent breaks.

Offer a heat stress training program before beginning outdoor work. Relevant content includes the proper use of heat-protective clothing and equipment, the effects of drugs and alcohol on heat stress tolerance, prompt reporting of signs or symptoms of heat-related illness—in yourself or your colleagues—and actions to take if symptoms occur.

Managers should receive specific training on monitoring alerts, responding to heat warnings, responding to signs or symptoms of heat-related illness, including contacting emergency medical services, promoting hydration, and adhering to rest breaks.

In addition to training, employers should reduce heat stress in the workplace through technical and organizational measures. Technical modifications to the work environment could include screens that reflect sunlight or absorb heat.

Organizationally, tasks or work schedules can be adjusted: for example, by limiting time spent in hot weather, allowing longer recovery times in cool, shady areas, increasing the number of employees per task, or providing sufficient cool drinking water. The strain caused by wearing personal protective equipment should also be reduced, and the use of additional cooling systems such as water-cooled clothing or cooling vests should be tested.

Other strategies include forming a multidisciplinary workgroup—for example, comprised of employees, qualified healthcare providers, and safety officers—and implementing medical screening programs and self-monitoring programs. The use of wearable monitoring devices, such as heart rate monitors to assess workload, may also be beneficial. A buddy system, in which employees monitor for signs of heat-related illness in others, is also recommended.

Humans can adapt to higher temperatures – for example, through increased sweating. This requires repeated exposure to the heat. This is especially important for employees who work outdoors during heat waves.

Employers should therefore develop acclimatization plans for hot conditions that gradually increase the duration of heat exposure and physical demands. This process typically takes place over a period of seven to 14 days. New employees require more time to adjust than those who have previously been exposed to heat. Re-acclimatization may also be necessary after an absence of a week or more.

How well individual employees adapt to heat also depends on their physical fitness and the respective heat stress. Gender differences should also be taken into account: Women generally require greater intensity, frequency, and duration of heat exposure to adapt. Because the scientific literature to date has primarily focused on men, current guidelines often fail to take these physiological differences into account. Employers should therefore test and adapt their own acclimatization plans.

As the risk of heatwaves increases, employers should take a long-term approach. The World Health Organization's Guide to Heat Action Plans provides important principles for this.

Just as airlines incorporate weather into their planning, companies should also use accurate weather forecasts to issue timely warnings, set thresholds for action, and clearly communicate risks. Close collaboration with local health systems and emergency services can further support this.

Additionally, create a communications plan that clearly defines what information will be shared, when, and to whom. Consider that multiple environmental health issues may occur simultaneously—such as extreme heat and air quality impacted by wildfires. Keep communication lines short to avoid overwhelming your employees with complex or contradictory instructions. Adapt your messages to local conditions.

Your heat health action plan should include both short-term and medium-term measures—such as reducing indoor heat exposure, increasing protection for outdoor workers, and a care strategy for vulnerable groups. In the long term, you should also consider the design and location of buildings and access to transportation to reduce heat stress for employees commuting to and from work.

Continuously review the effectiveness of your strategy over time. Establish real-time monitoring and evaluation, especially for outdoor employees, and also document the monitoring of indoor spaces. Maintain quality and consistency to ensure all legal requirements are met. Safety checklists and proven standards from the aviation industry can be particularly helpful here.

Extreme heat can significantly impact the performance and health of your most important asset – your employees. As extreme temperatures become more common, employers are required to effectively protect their workforce now and in the future.

© HBP 2023