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Temperature and Ventilation

What you need to know to ensure a safe working environment.

Last updated: 27 October 2020

All workplaces are covered by the Health & Safety at Work Act 1974 (HSW Act), which sets out the general duties and responsibilities an employer has towards employees and members of the public. In regard to temperature these are amplified in the Workplace (Health, Safety and Welfare) Regulations that state ‘all reasonable steps should be taken to achieve a comfortable temperature.’ Thermometers should be provided by the employer in each workplace/room.

If the temperature where you work is too hot or cold insist that it is measured.  ‘The temperature inside the workplace should prove reasonable comfort without the need for special clothing. If reasonable comfort cannot be achieved because of hot or cold processes, all reasonable steps should be taken to achieve a temperature which is as close as possible to comfortable.’ - Workplace (Health, Safety and Welfare) Regulations ACOP.

A long-running problem for all workers is that although the HSE indicates levels for the lower end of temperatures (normally at least 16˚ C or 61˚ F), unless much of the work involves severe physical effort, in which case it should be at least 13˚ C (55˚ F) they do not do the same for higher temperatures.

Many unions across the world and government authorities have indicated maximum temperatures above 24/25˚C start to cause problems for workers (above 27˚C there is recognition of health problems) and humidity over 40% (some say 30%) generally makes things worse. Low humidity can also cause problems (starting from 20% and lower).

At the extremes where people have to work in high heat areas, this can lead to heat stress where the body’s core temperature starts to rise to a dangerous level, resulting in very serious health consequences.


Working in unsatisfactory thermal conditions without adequate supplies of fresh air can pose problems. The law says enclosed workplaces should be sufficiently well ventilated so that stale air is replaced at a reasonable rate. Air that is taken from the outside can normally be considered as ‘fresh’, and in many cases, windows or other openings will provide sufficient ventilation in some or all parts of the workplace. Workers should not be subject to uncomfortable draughts.

Mechanical ventilation systems (including air conditioning) should be regularly and properly cleaned, tested and maintained, to ensure that they are kept clean and free and clear from anything that may contaminate the air.