Thermal conditions - Yleistä


General information on topic

The way in which workers perceive thermal conditions in their workplace depends on, among other things, their personal characteristics, how used to hot or cold temperatures they are, the physical effort involved in their work and clothing. Working in unusually high or low temperatures puts more strain on the body and increases the risk of accidents and health problems.

Occupational safety regulations do not specify any limit values or levels for thermal conditions that would trigger a responsibility for the employer to take action to prevent such harmful effects. Risks relating to thermal conditions therefore need to be evaluated and actions chosen to reduce them on a case-by-case basis. As working in unusually high or low temperatures carries a special risk of illness, employers usually need to consult their occupational health care provider or other specialists to assess the associated risks and plan remedial actions.

Assessment of thermal conditions

The Finnish Occupational Safety and Health Act obligates employers to carry out an assessment to establish whether there are any situations in which their employees could encounter adverse thermal conditions. If such circumstances are found, it is the employer’s duty to evaluate the effect of such adverse thermal conditions on their employees’ health and safety and, if necessary, decide on steps to lower the risk.

In the absence of limit values for thermal conditions, the significance of adverse thermal conditions must be evaluated on a case-by-case basis, in connection with the occupational health care provider’s workplace survey, for example. To make the process easier, the Finnish occupational safety and health administration has come up with the following recommendations for air temperature and flow rate based on the physical effort involved in different kinds of jobs:

Physical effort involved in the work Heat production Recommended temperature Air flow rate
light desk work under 150 W 21–25 °C less than  0,1 m/s
other light work 150–300 W 19–23 °C less than  0,1 m/s
moderate work 300–400 W 17–21 °C less than 0,5 m/s
hard work over 400 W 12–17 °C less than 0,7 m/s


Relative humidity should be between 30 and 50 per cent.

Ways to improve thermal conditions

If the assessment shows that the thermal conditions in the workplace are not in compliance with the recommended temperatures and air flow rates, workers’ functional capacity can be assumed to deteriorate if the ambient air temperature exceeds 28 °C or falls below

  • 20 °C in the case of light desk work
  • 18 °C in the case of other light work
  • 15 °C in the case of moderate work, or
  • 10 °C in the case of hard work.

It is the employer’s responsibility to provide their employees with a work environment in which thermal conditions pose as little danger or risk as possible to their health and safety. The principal ways to achieve this include air conditioning and isolating sources of heat and cold as well as other technical solutions.

Job rotation and regular breaks can also be introduced to give employees who are exposed to cold temperatures or heat a chance to escape the unpleasant conditions at intervals. Clothing and other personal protective equipment can be provided to shield employees from cold temperatures or heat.

Health examinations of employees who work in unusually cold or hot conditions

The hands and feet of employees performing light work begin to get cold when air temperature drops below 10–12 °C. On the other hand, a work environment in which air temperature exceeds 28 °C is also a potential health hazard. Employers must instruct their occupational health care provider to evaluate the need for regular health examinations in connection with their workplace survey and, if necessary, to carry out regular health examinations on employees who work in these kinds of conditions.

Special regulations on thermal conditions

The nature of the work permitting, all windows and glass doors in the workplace must be made of a material or fitted with blinds or similar that protect employees from the harmful effects of heat from the sun.

Any work performed at heights and the operation of any work equipment that can be affected by the weather must be organised so as to not put workers’ safety and health at risk due to wind, the freezing of equipment, rain or snow, thunder or other weather phenomena. For example, ride-on diggers, excavators, tractors and forest machinery must have a cab to protect the operator from the elements. Tractors with an engine output of no more than 30 kilowatts are excluded.

Work performed during hot weather

If hot weather pushes the air temperature in a workplace above 28 °C despite air conditioning, it is the employer’s duty to limit the amount of time that their employees spend working in such conditions. Employees performing machine-paced light or moderate work must not spend more than 50 minutes in each one-hour period in temperatures of between 28 °C and 33 °C.

If air temperature rises above 33 °C, work must not be performed in periods of more than 45 minutes per hour. In other words, workers must be provided with an opportunity to spend between 10 and 15 minutes each hour working in a cooler space.

Thermal conditions - Työntekijälle


Instructions for employee

Always let your employer know if you feel that the thermal conditions in your workplace are not optimal or if you find the temperature in your workplace uncomfortable and the issue has not been addressed by the workplace survey or other assessments.

Make sure that your employer’s occupational health care provider has evaluated your need for regular health examinations if you work in unusually low or high temperatures (below 10–12 °C or above 28 °C).

If you have to work in hot weather, you can make yourself more comfortable by wearing light, loose-fitting clothing and by drinking plenty of fluids.

Thermal conditions - Työnantajalle


Instructions for employer

No limit values have been set for thermal conditions. However, it is the employer’s responsibility to ensure that air temperature, humidity and air flow as well as surfaces that radiate heat or cold pose as little danger or risk as possible to workers’ health and safety. The assessment of thermal conditions is a key component of any workplace survey, and it is the employer’s duty to ensure that their occupational health care provider carries out a sufficiently thorough assessment.

Thermal conditions - Lainsäädäntö

Thermal conditions - Muualla verkossa