Staying Safe at Work Despite the Heat

On hot days, heat and workplace safety often come into conflict. Construction workers and other outdoor workers then face a dilemma: Personal protective equipment is necessary to protect against hazards—but at the same time, it can feel like an added burden in high temperatures.

When employees remove their PPE because of the heat, it initially provides a sense of relief. At the same time, however, the risk of accidents and injuries increases significantly—for example, due to a lack of protection against mechanical hazards, flying sparks, or intense UV radiation. Short-term comfort is thus traded for long-term safety.

Effective heat management should therefore not mean having to choose between comfort and safety. Rather, the key is protective clothing that combines both: protection and comfort, even at high temperatures. Modern materials and technologies can help make clothing lighter, more breathable, and more ergonomic—thereby increasing wearer acceptance without compromising protection.

Construction work in the summer heat places special demands on protective clothing

The risks of heat seem obvious, but in practice they are often less easy to recognize than one might expect. This is because heat stress builds up gradually: it develops alongside physical work without being immediately noticed. As the duration of physical work increases, core body temperature rises and physiological processes change: people become less alert, react more slowly, and have less stamina. Studies conducted under physical exertion show that even moderate increases in core body temperature are sufficient to measurably affect performance—long before a situation is subjectively perceived as critical.

This is precisely what makes heat stress in the body such a particular challenge: it exacerbates existing risks without being clearly identifiable as the cause itself. While protective clothing meets defined standards and offers tested protection against external influences, standards can only indirectly reflect the extent to which this insidious thermal stress develops within the body and how quickly it affects performance and safety.

Small Change, Big Impact: Heat and Performance

To understand why even small changes in body temperature can have a major impact, it’s worth taking a look at how the body reacts to heat stress:

The human body can function reliably only within a narrow temperature range. Even slight increases in core body temperature have measurable effects. Thermal discomfort begins as early as about 37.5 °C—that is, only about half a degree above normal. What is initially perceived as merely «warm» can quickly develop into a noticeable burden.

«When exposed to heat stress, the difference between working safely and facing a significantly increased risk is often less than two degrees of core body temperature.»

As core body temperature continues to rise, performance declines. Studies on attention under heat stress during physically demanding work tasks show that concentration and reaction time can already decline significantly even before temperatures reach levels that are critical to health. Workers react more slowly, fail to hear signals more often, and perceive physical exertion as exhausting more quickly.

Studies in occupational physiology also show that heat exhaustion can occur at temperatures just above 38 °C—well below life-threatening thresholds. If core body temperature continues to rise, the focus shifts increasingly from maintaining performance to avoiding acute health risks. This transition is gradual: often, less than two degrees of core body temperature separates safe working conditions from a significantly increased risk. It is precisely this small difference that makes heat stress a particularly critical—and at the same time difficult-to-detect—risk factor in everyday work while wearing protective clothing.

Why Protective Clothing Plays a Key Role

In work situations involving high physical exertion and rising ambient temperatures, the way the body releases excess heat changes: As long as the environment is cooler than the body, the body releases heat directly into the environment—for example, through contact with surfaces, air movement, or radiation. These forms of heat dissipation are referred to as «dry» heat dissipation.

However, as the heat on the construction site increases, the effectiveness of these mechanisms decreases. The closer the ambient temperature gets to body temperature—or even exceeds it—the less heat the body can lose in this way. In such situations, the body essentially has only one mechanism left to dissipate excess heat: the evaporation of sweat.

From Material to Physical Response

How well this evaporation works depends largely on the water vapor permeability of the clothing. The key parameter here is the so-called Ret value (Resistance to evaporative heat transfer). It describes a material’s resistance to the evaporation of sweat. A high Ret value hinders this process: sweat cannot escape as easily, the cooling effect decreases, and the body retains more and more heat.

It is well established in occupational physiology that material properties have a direct impact on the body’s thermal stress. The key factor here is how effectively protective clothing facilitates the release of heat and moisture. Occupational health recommendations state that, during physical work, core body temperature should ideally not rise by more than about one to two degrees Celsius. If excess heat is effectively dissipated, this rise can be slowed—and the time during which workers can remain within these safe limits is extended.

High breathability of clothing plays a crucial role here. It supports the body’s heat dissipation and helps prevent a critical rise in core body temperature. If, on the other hand, heat is trapped by clothing that is not very breathable, thermal stress increases more rapidly. Workers then need to take more frequent breaks to cool down or may temporarily remove their protective clothing.

Breathable protective clothing can therefore play an important role: It helps maintain the body's thermal balance and helps sustain performance and safety for longer, even at high temperatures.

Conclusion: Optimized protective clothing is key to combating heat stress

Heat stress is a risk associated with physically demanding outdoor work, which is becoming increasingly common on construction sites as early as spring, but especially in the summer. It is physiologically measurable, scientifically proven, and can be mitigated through the use of appropriate protective clothing. Against this backdrop, it becomes clear that effective protection against heat cannot be achieved solely by complying with standards. Rather, what matters most is how well protective clothing helps the body dissipate heat and maintain thermal equilibrium.

Protective clothing that helps regulate body temperature and moisture extends the time during which workers can work safely, maintains their performance and alertness, and reduces the risk of heat stress building up further over the course of the workday. Breathable materials support the body’s natural heat dissipation and help prevent a critical rise in core body temperature.

Breathability, moisture management, and weight are therefore key safety factors. When selecting personal protective equipment, this means that—in addition to meeting the requirements of the standard—greater consideration should be given to the physiological realities of everyday work. After all, safety depends not only on the material but also on the person wearing it.