When Is It Too Hot to Work?
In recent years, heatwaves have become more frequent and intense across the globe, especially in Europe. From Italian farms to German warehouses, extreme heat poses a growing threat to the health and safety of workers. While high temperatures can be uncomfortable, they can also be dangerous—and in some cases, even fatal. Understanding when it's too hot to work, recognizing the symptoms of heat stress, and knowing how to stay cool are essential steps for every worker and employer.
Understanding Heat Stress: What It Is and Why It Matters
Heat stress occurs when the body cannot cool itself effectively. This can happen when environmental temperatures, humidity, and physical exertion combine to overwhelm the body's natural cooling mechanisms, such as sweating. When this happens, body temperature can rise to dangerous levels, leading to heat exhaustion or heat stroke.
Unlike other environmental hazards like air pollution, heat is an invisible threat. It doesn’t always feel unbearable until it’s already affecting the body. And while it’s easy to associate heat stress with outdoor jobs, indoor environments—especially those without proper ventilation or air conditioning—can be equally hazardous.
The World Health Organization and the International Labour Organization have both raised alarms over rising heat-related workplace illnesses and fatalities. In the European Union, workplace deaths from heat have increased by 42% since the year 2000. The risks are particularly high in labor-intensive sectors like agriculture, construction, transportation, and emergency services, but no workplace is immune.
How Hot Is Too Hot?
One of the main challenges in heat safety is determining when it's too hot to work. Unlike noise levels or chemical exposure, there is no universal legal threshold for heat across the European Union. Some countries have adopted national regulations, but many rely on guidelines rather than enforceable standards.
To assess heat risks, occupational health experts use the Wet Bulb Globe Temperature (WBGT) index. Unlike a regular thermometer, the WBGT considers multiple factors: temperature, humidity, wind speed, and solar radiation. It gives a more comprehensive picture of the thermal environment and the risks it poses to the human body.
According to occupational health guidelines, the following WBGT levels indicate escalating risk:
Low Risk: < 25°C
Moderate Risk: 25–28°C
High Risk: 28–31°C
Extreme Risk: > 31°C
In practice, any outdoor work performed in temperatures above 30°C (86°F), especially with direct sunlight and physical exertion, can be considered hazardous. For example, heatwaves in parts of Spain and Italy have pushed temperatures well beyond 40°C (104°F), creating dangerous conditions even for short periods of exposure.
Countries like France and Italy have implemented special measures during heatwaves, such as banning outdoor work during peak midday hours. In Germany, Belgium, and Greece, employers are advised—or in some cases, required—to modify working hours and provide cooling breaks when the temperature exceeds specific thresholds.
Who Is at Risk?
Certain groups of workers are more vulnerable to heat stress than others. These include:
Outdoor workers: Farmers, construction workers, landscapers, and delivery personnel often spend hours under direct sunlight.
Warehouse and factory workers: Poor ventilation and heavy machinery can turn indoor spaces into heat traps.
Public safety and emergency responders: These workers often wear heavy protective gear, which prevents sweat from evaporating and increases heat buildup.
Office workers in poorly ventilated buildings: Without proper air conditioning, indoor heat can reach unsafe levels.
Young or physically fit workers: Contrary to popular belief, being young and fit doesn’t guarantee safety. Many people don’t recognize the early signs of heat stress, especially if they underestimate the risks.
Older adults or individuals with preexisting conditions: People with heart disease, kidney problems, or respiratory conditions are especially susceptible.
Even short periods of intense heat can lead to serious complications. In one tragic case in Barcelona, a 51-year-old cleaner collapsed and died shortly after finishing his shift during a heatwave. Such incidents highlight the urgent need for awareness and preventive action.
Recognizing the Signs of Heat Stress
Timely recognition of heat-related illnesses is crucial. Heat stress symptoms often start subtly and can escalate quickly if ignored. Here’s what to watch out for:
Early Symptoms (Heat Exhaustion):
Heavy sweating
Fatigue or weakness
Dizziness or lightheadedness
Headache
Nausea or vomiting
Muscle cramps
Irritability or confusion
Pale, cool, or moist skin
Severe Symptoms (Heat Stroke):
Body temperature above 40°C (104°F)
Dry, hot, and red skin (no sweating)
Rapid pulse
Slurred speech
Loss of consciousness
Seizures
Heat stroke is a medical emergency. If not treated immediately, it can cause organ damage or death. Anyone showing symptoms of heat stroke should be moved to a cooler environment, provided fluids (if conscious), and given emergency medical attention.
How to Stay Cool and Safe at Work
Preventing heat stress involves both personal and organizational strategies. Here are practical steps that workers and employers can take:
1. Hydration
Drink water regularly—even if you're not thirsty. Avoid caffeinated, sugary, or alcoholic drinks, which can dehydrate you. Electrolyte-replenishing drinks may be beneficial during prolonged exertion.
2. Clothing
Wear light-colored, loose-fitting, breathable clothes. When working outside, wear a wide-brimmed hat and sunglasses. If protective gear is required, make sure it's designed for heat (e.g., ventilated or moisture-wicking).
3. Breaks and Rest
Take frequent breaks in shaded or air-conditioned areas. Rest periods help the body recover and regulate temperature.
4. Modify Work Schedules
Work during cooler parts of the day (early morning or evening). Avoid strenuous tasks during peak heat hours (usually 12–4 PM). Some countries already implement mandatory siestas or “heat rest” policies during extreme weather.
5. Cooling Measures
Use fans, misters, and cooling towels. Cold compresses on the neck, wrists, or forehead can help lower body temperature.
6. Acclimatization
Gradually increase workload for new employees or those returning after time off. The body takes time (up to two weeks) to adjust to high temperatures.
7. Training and Awareness
Educate workers and supervisors about the signs of heat stress and emergency procedures. Regular briefings during hot spells can prevent serious incidents.
Know Your Rights as a Worker
Workers in the European Union are legally entitled to safe working conditions, even though there is no EU-wide law specifically regulating work in extreme heat. The EU-OSHA (European Agency for Safety and Health at Work) mandates employers to assess workplace hazards—including heat—and take appropriate steps to mitigate risks.
Several countries have additional laws:
France: Employers must provide free drinking water and adjust work conditions during heatwaves.
Italy: Outdoor work is banned during the hottest hours in some regions.
Germany and Spain: Employers are required to ensure safe temperatures and allow for breaks in shaded areas.
Workers also have the right to stop work if their health is at immediate risk due to unsafe heat conditions. However, this right is not always well understood or enforced. In many cases, workers may fear retaliation or job loss if they raise concerns.
Labor unions such as the European Trade Union Confederation (ETUC) advocate for stronger heat protection laws, including mandatory medical checks during heatwaves and the right to refuse unsafe work without penalty.
If you're unsure about your rights, consult your employment contract or speak with your workplace representative or union.
The Bigger Picture: Climate Change and the Future of Work
The increasing frequency of heatwaves is not just a seasonal issue—it’s a symptom of climate change. As global temperatures rise, workplaces will need to adapt. Urban planning, building design, labor laws, and public health strategies all have roles to play in ensuring that workers remain safe.
Employers and policymakers must act proactively, not reactively. This means designing heat-resilient workplaces, providing climate-appropriate personal protective equipment, and updating occupational health standards to reflect modern realities.
Governments should also support research and data collection. Many heat-related work illnesses and deaths go unreported, leading to an underestimation of the true impact. Transparent reporting systems and national heat action plans could help prevent future tragedies.
Conclusion
Working in extreme heat is becoming an unavoidable reality for millions of people. But it doesn’t have to come at the cost of health or life. By understanding when it's too hot to work, recognizing the signs of heat stress, taking preventative steps, and knowing their legal rights, workers can better protect themselves.
Employers, too, have a critical responsibility—not only legally but morally—to ensure that no one is forced to choose between a paycheck and their well-being. With awareness, planning, and solidarity, we can build a future where heat doesn’t cost lives
