In the summer of 2025, the Ministry of Health estimated 3,832 deaths attributable to excessive heat in Spain, an 87.6% increase from the previous year. Between May and September, 870 Level 3 extreme heat alerts were recorded, 73% more than in 2024. Behind these figures are, among others, workers exposed to heat without the protective measures required by law.
Extreme heat is a recognized, assessable, and preventable occupational hazard. This article explains What do the regulations say?, What obligations do companies have, and how should they respond to each AEMET alert level?.
Why Does Summer Increase Workplace Risks?
When the ambient temperature exceeds the body's ability to regulate its internal temperature, physiological responses occur that can lead to serious health conditions. The problem is exacerbated when work involves physical exertion, direct sun exposure, or poorly ventilated indoor environments. The 2025 National Plan for Preventive Measures, In effect from May 16 to September 30, it identifies occupational exposure as one of the main environmental risk factors.
Health Effects of Exposure to High Temperatures
Heat cramps
First warning sign. These occur due to the loss of mineral salts through sweat and affect the muscles being used during work.
Dehydration
Water loss without adequate replacement reduces blood volume and impairs concentration, reaction time, and decision-making, increasing the risk of workplace accidents.
Heat Exhaustion
It occurs when the body cannot maintain the blood flow needed to cool the body and supply the muscles at the same time. The worker must be removed from the heat immediately.
Heatstroke
A result of prolonged sun exposure. It presents with severe headache, nausea, and redness of the skin. It is a warning sign that should be addressed before it worsens.
Heatstroke
The most severe form and a medical emergency. The body loses its ability to regulate its temperature, and the internal temperature can exceed 40°C. Symptoms include confusion, seizures, and loss of consciousness. Call 112 immediately.
Which sectors and workers are most at risk?
| Sector | Most Viewed Profiles | Risk Level | Primary exposure factor |
|---|---|---|---|
| Construction | Laborers, formwork carpenters, rebar workers, machine operators | Very high | Outdoor work, intense physical exertion, and direct sun exposure during the middle of the day. |
| Energy and Infrastructure | Maintenance technicians, photovoltaic system operators, outdoor electricians | Very high | I work on roofs, outdoor installations, and metal surfaces that amplify solar radiation. |
| Agriculture | Farmworkers, seasonal workers, harvesters | Very high | Continuous exposure to the sun, strenuous physical activity, and frequent lack of access to water and shaded areas. |
| Transportation and Logistics | Delivery drivers, warehouse workers, loading and unloading workers | High | Vehicle cabins without adequate climate control and warehouses or storage facilities without temperature control. |
| Industry and Manufacturing | Production, foundry, welding, and industrial furnace operators | High | Heat generated by the production process itself, combined with high physical exertion and enclosed spaces without adequate ventilation. |
| Hospitality and Food Service | Chefs, kitchen staff, waitstaff on the patio | High | Heat from kitchen equipment, confined spaces, and working outdoors during the hottest part of the day. |
| Urban Services and Street Cleaning | Cleaning workers, municipal gardeners, waste collection workers | High | Direct sunlight throughout the day in urban environments with a heat island effect. |
| Offices without adequate air conditioning | Administrative, technical, and customer service staff | Moderate | Temperatures above 27°C in enclosed spaces that exceed the legal limits set forth in Royal Decree 486/1997. |
Regulations on Occupational Heat-Related Hazards
The legal framework is supported by several complementary regulations. The Law 31/1995 on Occupational Risk Prevention establishes the obligation to ensure the safety and health of workers, including protection against heat stress. The Royal Decree 486/1997 sets maximum indoor temperatures: 27°C for sedentary work and 25°C for light work. The Royal Decree-Law 4/2023 requires that working conditions be adjusted or working hours be reduced when the AEMET issues orange or red alerts and preventive measures are not sufficient. Royal Decree-Law 8/2024 introduces the paid climate leave: up to four days when weather conditions prevent access to the workplace.
Employers' Obligations and Employees' Rights
| 📋 Employer Obligations | ✅ Workers' Rights |
|---|---|
| Include heat stress in occupational risk assessmentsLaw 31/1995 on Occupational Risk Prevention, Art. 16 | To work under conditions that do not endanger their health or safety |
| Ensure a maximum temperature of 27°C in offices and 25°C for light indoor workRD 486/1997, Annex III | Understand the heat-related risks at your workstation and the applicable preventive measures |
| Provide accessible, free, fresh drinking water in the workplaceRD 486/1997, Annex V | Receive fresh, safe drinking water at no cost throughout the day |
| Adjust working conditions or reduce working hours in response to AEMET orange or red alerts when preventive measures do not ensure safetyRDL 4/2023 | Suspend operations in the event of a serious and imminent risk without incurring financial loss or penaltiesLaw 31/1995 on Occupational Risk Prevention, Art. 21 |
| Provide appropriate PPE for outdoor work: a hat, breathable clothing, sunscreen, and sunglassesLaw 31/1995 on Occupational Risk Prevention, Art. 17 | Receive appropriate PPE free of charge for outdoor work in hot conditions |
| Provide cool, shaded rest areas for outdoor work | Take breaks in cool areas as often as necessary to prevent heatstroke |
| Grant up to 4 days of paid leave when adverse weather conditions prevent employees from getting to workET Art. 37.3.g, RDL 8/2024 | Receiving full pay if the workday is shortened or interrupted due to extreme heatRoyal Decree 1561/1995, Art. 23.3 |
| Provide training and information on the symptoms of heatstroke and the protocol for responding to itLaw 31/1995 on Occupational Risk Prevention, Art. 19 | Report noncompliance to the safety officer or the Labor Inspectorate without fear of retaliation |
How should work be organized in the event of weather alerts?
- Keep the risk prevention plan up to date, including the section on heat stress
- Ensure that fresh water is available at all workstations
- Train employees on the symptoms of heat stroke and the protocol for responding to it
- Review the positions with the highest exposure and identify vulnerable workers (those over 65, those with chronic illnesses)
- Increase fluid intake and make sure to take breaks in cool areas
- Avoid physically strenuous tasks between 12:00 p.m. and 5:00 p.m.
- Notify employees of the alert and remind them of the response protocol
- Adjust working conditions if preventive measures do not ensure safety
- Modify or reduce the workday: start earlier and/or suspend operations during the middle of the day
- Prohibit physically demanding outdoor work between 12:00 p.m. and 5:00 p.m.
- Provide cool, shaded rest areas that are easily accessible
- Strengthen monitoring of vulnerable workers and implement frequent rotations
- Suspend work outdoors and in non-air-conditioned spaces where safety cannot be guaranteed
- Grant paid weather-related leave if conditions prevent access to the workplace (up to 4 days; Labor Code, Art. 37.3.g)
- Workers may halt work due to a serious and imminent risk without suffering financial loss or facing penalties
- Activate the heat emergency protocol: identify symptoms, call 112 if you suspect heatstroke
- Notify the safety representatives of the situation and document all measures taken
How can we protect workers from the heat?
The preventive measures are organized around four main areas: schedule planning (Tackle the most strenuous tasks first thing in the morning and avoid the 12:00 p.m. to 5:00 p.m. time slot), hydration (Drinking water is available at the station; the recommended intake is 250–300 ml every 20 minutes.), personal protective equipment (breathable clothing, a hat, sunscreen, and sunglasses for outdoor activities—always provided by the company) and training (All employees must be familiar with the warning signs and the protocol for responding to them.).
If you or a colleague experiences heatstroke: call 112, move the person to a cool place, and apply cold compresses or water until help arrives.
Frequently Asked Questions About Heat-Related Occupational Hazards
At what temperature does it become impossible to work?
The law does not set a single limit. Indoors, Royal Decree 486/1997 establishes maximum temperatures of 27°C (sedentary work) and 25°C (light work). Outdoors, the guideline is the AEMET heat alert: if the alert is orange or red, the company must adjust the work schedule or suspend operations.
How many breaks should you take during a heat wave?
The regulations do not specify an exact number, but they require employers to take the necessary measures. Occupational safety and health services recommend taking breaks every 30–45 minutes during physically demanding outdoor work.
When are the periods and times of greatest risk?
The National Heat Plan was in effect from May 16 to September 30. The hours of greatest risk outdoors are from 12:00 p.m. to 5:00 p.m., especially in July and August.
Is it mandatory to provide water to workers?
Yes. Annex V of Royal Decree 486/1997 stipulates that fresh, potable water must be available, accessible, and free of charge in the workplace.
