Finnish Institute of Occupational Health media release 1 December 2025
The Finnish working population is adapted to cooler conditions. This is why especially the first waves of summer heat and the onset of working in the heat put a strain on the body and can impair work ability. Approximately 60 000 people work in hot conditions every day in Finland.
Occasionally, up to ten times as many employees are exposed to heat. Now workplaces have access to recommendations for scheduling breaks when working in high temperatures, tailored specifically to Finland's climate.
– Working must always be safe for the employees. The new break recommendations for working in the heat will help workplaces in preparing for heat waves and ensuring safe work, says Jutta Karkulehto, Researcher at the Finnish Institute of Occupational Health.
Half an hour of heavy work in high temperatures can overheat the body
Previous guidelines recommended taking breaks when the environmental temperature rises, but the intensity of work was not considered. A new study examined how moderate and strenuous work in high temperatures affect an employee’s physical strain and recovery as well as cognitive performance. The results revealed that work intensity affects body temperature to a greater extent than the temperature of the environment.
– We observed that body temperature rises above the safe limit of 38 °C within the first half hour when the work is physically demanding and done in high temperatures, Karkulehto says.
For example, in rescue operations or the industrial and construction work in high temperatures quickly raises the body’s core temperature. That weakens muscle strength and ability to concentrate, which increases the risk of accidents. If heavy work in hot conditions continues for several hours, cumulative heat stress occurs. Body temperature rises even faster and longer breaks are required for recovery.
– In prolonged work in high temperatures, the length of work periods must be shortened and the length of breaks increased, because heat load accumulates in the body despite the breaks. Employees also react to heat individually, which is important to remember when planning the work, Karkulehto says.
Clear instructions for working in the heat
Although the health risks associated with work in high temperatures are severe, they can be managed through planning ahead. Finnish workplaces are already better prepared for employees’ heat exposure during outdoor work, but there is still room for improvement. It is advisable to plan work in high temperatures in advance, even if the workplace only occasionally operates in hot conditions. In such cases, the employees are not adapted to working in heat, and the risks increase.
The Finnish Institute of Occupational Health’s recommendations provide a model for planning work and breaks in advance as well as concrete guidelines for breaks and recovery. The recommendations are intended for the employees working in high temperatures, occupational safety and health personnel, as well as supervisors to help in organizing the work.
New recommendations for working in the heat:
- In temperatures above +30 °C, strenuous work should only be done for up to 30 minutes without a break.
- If strenuous work continues after a break, the working time between breaks shortens, even if the recommended breaks are taken.
- When strenuous work is performed in high temperatures, recovery requires at least a 20-minute break. If the strenuous work continues, breaks need to be longer.
- At room temperature, it usually takes 45–60 minutes for the body to cool down.
The Work in the heat - risk management at workplaces (HeatFit) project was funded by the Finnish Work Environment Fund. Partners of the project are the Finnish Food Workers’ Union, Talonrakennusteollisuus ry (Confederation of Finnish Construction Industries, CFCI), and Päällystealan neuvottelukunta ry (the Finnish Asphalt Pavement Association, FAPA).
Further information
- Jutta Karkulehto, Researcher, The Finnish Institute of Occupational Health, jutta.karkulehto [at] ttl.fi, +358 30 474 2795
