Heat Stroke and Heat Exhaustion in the Workplace: Early Recognition and Prevention | Wellbeing

Statistically, thousands of workers face heat-related health issues annually, predominantly within the construction, manufacturing, transportation, and agricultural sectors. Early recognition of the signs and the implementation of effective preventive measures will help businesses protect worker health, minimize occupational accidents, and ensure strict compliance with legal regulations.

1. What are Heat Exhaustion and Heat Stroke?

1.1. Heat Exhaustion

Heat exhaustion is the early warning stage of heat-related illnesses. It is a condition characterized by severe dehydration and electrolyte loss due to prolonged exposure to a hot environment or strenuous physical labor. It is typically accompanied by heavy sweating, nausea, vomiting, headaches, dizziness, abdominal cramps, severe fatigue, and an elevated core body temperature ranging from 37.7°C to 40°C.

This is a critical warning phase. If not treated promptly, it will progress into heat stroke—the most dangerous stage where the core temperature exceeds 40°C, causing central nervous system dysfunction and threatening multi-organ failure.

1.2. Heat Stroke

Heat stroke is the most critical and life-threatening stage of heat-related illnesses. It occurs when the body's thermoregulatory mechanism completely collapses. At this point, the ability to sweat decreases drastically, and the core temperature spikes rapidly, leading to severe brain, cardiovascular, and kidney damage. Heat stroke can occur suddenly with subtle or no warning signs, especially in individuals performing strenuous work under the harsh midday sun.

Symptoms often develop rapidly and severely. Initial signs include agitation, severe headache, flushed/hot/dry skin, lethargy, shortness of breath, nausea, vomiting, and sometimes abdominal pain. Without immediate and correct first aid, the body temperature will quickly exceed 41°C. The victim will experience dizziness, a pale complexion, and a rapid pulse. In severe cases, this rapidly progresses to delirium, convulsions, coma, cardiovascular collapse, and death due to multi-organ failure.

In the workplace, these two conditions frequently co-occur due to outdoor labor under the sun, poorly ventilated factories, or the use of heavy, impermeable protective clothing.

2. Early Warning Signs of Heat Stress

Early recognition is the deciding factor in successfully preventing heat stroke and heat exhaustion. During the heat exhaustion phase, workers typically exhibit the following manifestations, depending on exposure time and the degree of core temperature elevation:

• Mild Symptoms: Extreme fatigue, excessive thirst, dizziness, rapid heart rate (tachycardia), rapid breathing, palpitations, and heat cramps.

• Severe Symptoms: Excruciating headache, progressive shortness of breath, severe nausea or vomiting, weakness or hemiplegia, convulsions, fainting or coma, and cardiovascular collapse (rapid heartbeat, plummeting blood pressure), which can be fatal.

Many workers subjectively dismiss these symptoms as "just being tired from the heat," missing the golden window for intervention. At the enterprise level, managers and colleagues must pay special attention to high-risk groups, including:

• The elderly, young children, and pregnant women.

• Individuals performing high-intensity labor outdoors for prolonged periods or in hot environments (e.g., agricultural workers, brick kiln workers, steel mill workers).

• Individuals with chronic conditions such as hypertension, Chronic Obstructive Pulmonary Disease (COPD), asthma, and diabetes.

3. Causes of Heat Stroke and Heat Exhaustion at Work

The occupational environment is the pivotal factor. High temperatures combined with high humidity hinder the body's ability to dissipate heat through sweat evaporation. Industries that require acute focus on heat stress prevention include construction (working under the sun), metallurgy, food production (near industrial ovens), transportation (driving in cabins without A/C), and agriculture.

Additionally, heavy labor intensity, continuous work without adequate rest breaks, lack of drinking water, and wearing impermeable Personal Protective Equipment (PPE) are common culprits. Climate change is exacerbating this issue, with average temperatures steadily rising across many industrial zones.

4. Effective Prevention Measures

Preventing heat-related illnesses requires a synchronized effort from the corporate management level down to the individual worker.

4.1. Employer Responsibilities

According to QCVN 26:2016/BYT on Workplace Microclimate (issued alongside Circular 26/2016/TT-BYT by the Ministry of Health), enterprises must maintain air temperatures appropriate for the labor type: 20–34°C for light work, 18–32°C for medium work, and 16–30°C for heavy work; alongside a humidity level of 40–80%. Wind speed and thermal radiation intensity must remain within permissible limits. Enterprises are responsible for conducting periodic occupational environmental monitoring, installing ventilation and cooling systems, and providing adequate sunshades.

Furthermore, Article 18 of the 2015 Law on Occupational Safety and Health mandates that employers assess and control hazardous factors to implement technical safety measures and safeguard worker health. Therefore, heat risks must be routinely evaluated, reasonable rest schedules must be arranged, and workers must be equipped with breathable protective clothing, wide-brimmed hats, and UV-blocking sunglasses.

4.2. Employee Responsibilities

Every individual must proactively implement the following measures to prevent heat stroke and heat exhaustion:

• Hydrate Frequently: It is crucial to stay hydrated when working outdoors, especially in hot weather. Drink water or electrolyte fluids continuously throughout the day, even if you do not feel thirsty.

• Wear Loose, Light-Colored Clothing: Loose-fitting and light-colored garments help keep the body cool. Avoid dark clothing as it absorbs thermal radiation.

• Rest in the Shade: Take regular rest breaks in shaded areas to cool down. If possible, schedule heavy tasks in the shade during peak heat hours.

• Apply Sunscreen: Sunscreen protects the skin from harmful UV rays. Apply it generously to exposed skin before heading outside and reapply every two hours, or more frequently if sweating heavily.

• Wear Hats and Sunglasses: These items protect the face and eyes from direct UV exposure.

• Recognize Heat Stress Signs: If you experience any symptoms of heat stress—such as dizziness, nausea, or vomiting—stop working immediately and move to a cool area. Drink water and rest. If symptoms persist, seek medical attention immediately.

5. First Aid for Heat Stroke and Heat Exhaustion

When encountering heat-related health issues, rapid and appropriate first aid measures must be applied based on symptom severity:

5.1. For Mild Cases:

• Move the victim immediately to a cool, well-ventilated, and shaded area.

• Loosen restrictive clothing or remove outer layers.

• Active Cooling: Rapidly lower the core body temperature to below 38°C within 30 minutes using the following methods:

• Ice Packs and Misting: Spray plenty of cool water directly onto exposed skin. Place ice packs on the armpits, groin, and neck (areas with large blood vessels). Use a fan to accelerate evaporation. This is a critical, continuous on-site measure before and during transport to a medical facility.

• Cold Water Immersion: Immersing the victim in cool water (approx. 20°C) can drop the temperature by 0.15-0.24°C per minute. This is highly effective for younger individuals but should be used with extreme caution for the elderly or chronically ill.

• Evaporative Cooling: Continuously mist water onto the skin while fanning vigorously. Specialized cooling tents can be used if available.

• If the victim is fully conscious and able to swallow, provide small sips of cool water. The best option is an electrolyte-replenishing fluid, such as properly mixed Oral Rehydration Salts (ORS / Oresol).

• If the victim experiences heat cramps, gently massage the affected muscles.

• Note: Do not let crowds gather around the victim, as it restricts airflow. Symptoms usually subside within 10 to 15 minutes of proper cooling.

5.2. For Severe Cases:

If the victim exhibits severe symptoms, call emergency services (115) immediately or rush them to the nearest medical facility. Specifically, for sudden-onset heat stroke where the core temperature is life-threateningly high, emergency cooling must be executed aggressively to lower the temperature as fast as possible.

• Transfer victims of severe heat exhaustion or heat stroke to a medical facility equipped for comprehensive resuscitation early. Ensure continuous cooling methods are applied throughout the transport process.