Heat can negatively affect the body and increase the risk of accidents

People experience discomfort from heat even with small deviations from the ideal temperature. Heat is also a physical stress on the body. Extreme heat can therefore pose risks and be hazardous to health, especially in combination with heavy work and high humidity.

Heat is a physical stress on the body and can increase the risk of ill health. Different individuals react differently to heat stress. People with cardiovascular disease, kidney problems or severe obesity are especially sensitive. The ability to work is also affected because extreme heat affects both body and mind.

Attention and judgement deteriorate, thereby increasing the risk of accidents. The body's natural response to extreme heat is to slow down the work rate so as to reduce the body's heat production.

Risks from heat when working outdoors

When working outdoors in the summer, employees are often exposed to heat. Since physical activity is usually higher when working outdoors than indoors, this increases the heat stress.

High temperature can cause discomfort in the form of skin redness, headaches, irritability and nausea. But it can also lead to more serious health effects such as heat stroke. Strong sunlight is another risk if there is no possibility of shade. If a person is exposed to direct sunlight, the temperature can become very high with an increased risk of negative health effects. Exposure to UV radiation also increases, which can lead to various types of skin damage and ultimately to skin cancer.

To cool down and get rid of excess heat when it is hot, the body sweats. A person who sweats loses a lot of fluid and some salt. In the summer, it is more difficult to get rid of excess heat through sweating due to high humidity. This makes evaporation from the skin more difficult and thus the cooling effect is less.

  • When it is hot, you need to drink a lot to avoid dehydration. The fluid loss caused by sweating is most easily compensated for by drinking plain water. Special salt supplements are normally not needed.

    Drinking water must be provided in a hygienic way within a reasonable distance from the workplace. What distance is reasonable depends on the nature of the activity.

    Outdoor workplaces – temporary measures in case of high temperatures

    • Protect both permanent and temporary outdoor workplaces from the weather
    • Adjust working hours if possible – work when the sun is not at its highest
    • Take regular breaks in a cooler environment
    • Drink water
    • Use appropriate clothing and sunscreen if necessary.

Risks from heat indoors

The risks from heat indoors are the same as outdoors. High temperature can cause discomfort in the form of skin redness, headaches, irritability and nausea. Different individuals react differently to heat stress. However, with work that is less physically demanding, such as office work, the risk of serious health effects is small. But if the temperature is high, many people experience discomfort.

In industry, there are workplaces with greatly raised temperatures. There, employees may need protective clothing and to take regular breaks at normal room temperature.

Working in intense heat

  • In premises such as schools and offices, high indoor temperatures are usually linked to the outdoor climate. In such premises, it is the people themselves who are generate most of the heat. Next come lighting and computer equipment.

    Workplaces can also become too hot due to the activities being performed. In many industrial premises, most of the heat comes from various hot processes, such as furnaces.

    The sun can also cause high temperatures when it shines through windows or onto roofs and walls. Poor ventilation can also lead to excessively high temperatures, or if air intakes are located on the sunny side of a building.

  • Windows and skylights should, where necessary, have devices or designs that allow for shielding from solar radiation when needed. Examples of solar shielding include façade screens, awnings, blinds, heat-reflecting glass and curtains. Of these, external shielding normally provides the best effect.

    Curtain

    Approximate effect: about 20 per cent

    Blinds between glass

    Approximate effect: about 30 per cent

    Awning or external blind

    Approximate effect: about 60 per cent

  • When it is hot, you need to drink a lot to avoid dehydration. The fluid loss caused by sweating is most easily compensated for by drinking plain water. Special salt supplements are normally not needed.

    Drinking water must be provided in a hygienic way within a reasonable distance from the workplace. What distance is reasonable depends on the nature of the activity.

  • One way to relieve heat discomfort is to increase air speed with open windows or fans, for example. Ventilate on the shady side where the air is cooler.
    Normally, people perceive drafts as cold. But in warm climates, much higher air speeds can be accepted and are then perceived as comfortable.

    Make sure that the ventilation complies with the regulations for the activity. Ventilation can also be run at night to lower the temperature of the building.

  • In summer, the indoor temperature should normally be 20–26°C if the work is light and sedentary. Ventilation systems and comfort cooling are normally not designed to keep to the upper limit with extra high outdoor temperatures. This applies to occasional extremely hot days, as well as short periods of high temperatures – heat waves.

    According to SMHI, the Swedish Meteorological and Hydrological Institute, a heat wave is when the outdoor temperature is 25°C or more for at least 5 consecutive days. For a few days a year, it is therefore permissible for it to be so hot that it is not perceived as comfortable.

    Indoor workplaces – temporary measures in case of high temperatures

    • Limit sun exposure
    • Wear lighter clothing
    • Drink more water
    • Screen off or move machines that emit heat
    • Turn off unnecessary heat sources
    • Increase air exchange through window ventilation on the shady side of the building
    • Run the ventilation at night
    • Use table fans
    • Adjust working hours
    • If possible, work at home – if it is cooler there.

Get a better work environment through working systematically

As an employer, you must manage the work environment systematically, so as to improve it. Our provisions for systematic work environment management apply to all employers – regardless of the activities or the risks that you and your employees could be exposed to.

The employer is responsible for the risks from heat in the workplace

As an employer, you are responsible for reducing the risk from high temperatures, just as you are responsible for all aspects of the work environment. You must be familiar with the Work Environment Act and other work environment regulations.

Employees and safety representatives are important for a good work environment

Employees and safety representatives have an important role in work environment management. As an employer, you must give all employees the opportunity to participate in work environment management. For example, you can let employees suggest measures or provide feedback on measures you have implemented.

Employees' participation in work environment management

As an employee, you must participate in work environment management and participate in implementing the measures needed to achieve a good work environment. You must follow the employer's instructions. You must also report to your employer or your safety representative if the work involves immediate and serious danger to life or health.

 

Last updated 2025-04-09