Controlling the work environment

work environment

The work environment, regardless of the work being done, impacts on employees’ health and safety. As such it is important to understand how employers can control air quality and temperature issues.


The Approved Code of Practice (ACOP) to the Workplace (Health, Safety and Welfare) Regulations 1992 suggested a minimum temperature of 16°C after the first half hour of work at the premises or 13°C if exertion is involved and there is no suggestion that this is likely to change due to the abolition of the ACOP itself.

For light sedentary occupations the recommended winter temperature is 22°C +/– 2°C and the recommended summer temperature is 24.5°C +/– 1.5°C.

Thermometers should be provided so the temperature can be checked. There is no legal maximum temperature.


Every person needs to be provided with a minimum supply of outdoor air for the duration of the work period. This air should be fresh and clean, and uncontaminated by discharges from flues, chimneys or other process outlets.

A minimum of 5–8 litres per second per person of outdoor air is recommended. Less than this will increase the level of pollutants, in particular carbon dioxide (CO2) produced from human respiration.

Ventilation should remove and dilute warm, humid air and provide air movement which gives a sense of freshness without causing a draught. It should also maintain oxygen and monitor CO2 levels.

In most workplaces windows will provide sufficient ventilation. However, if process or heating equipment in the workplace produces dust, fumes or vapours, mechanical ventilation will be needed to remove these.


Relative humidity is the amount of moisture contained in the air compared to the amount of moisture that the air is capable of holding.

The recommendation for working environments is a relative humidity of 40–60%. Levels outside these parameters can be tolerated but should not be maintained for long periods.

Drinking Water

To mitigate any effects of high temperatures and low relative humidity, employers should maintain a clearly labelled, adequate supply of wholesome drinking water, either with an upward drinking jet or suitable cups. This should be located so that it is easily accessible from the work area but not situated near electrical equipment or where a slip hazard could occur if there is a spillage.

Risk Assessment

Temperature/humidity/air supply is a complex area to control due to the interaction of factors such as:

  • The temperature and relative humidity of external air
  • Internal heating and air-conditioning systems
  • The extent of any natural vegetation
  • The activities engaged in by building occupants
  • The amount of machinery and equipment in use.

None of these is likely to be constant and so the indoor environment will vary according to:

  • The weather
  • The time of day
  • The season
  • The settings and effectiveness of building services
  • What is taking place in each work area.

In addition, the higher the air temperature, the more water vapour the air can hold, affecting occupants’ perceptions of stuffiness. Personal preferences and individual tolerance levels vary enormously.

The person(s) responsible for maintaining a safe and healthy working environment should accept that as long as the risks have been assessed, reasonable control measures have been taken and the environment continues to be monitored, some occupants may still not regard the environment as comfortable.

However, there are two ways in which employees’ perceptions should be taken into account.

  • Wherever possible local controls should be in place.
  • Any problems reported, especially those relating to the safety and health of occupants and visitors, should be investigated promptly.

The risk assessment should consider the following factors.

  • Are workers expected to carry out very different tasks in the same environment?
  • Are temperature, ventilation and relative humidity controls set at the appropriate levels for the activities being carried out?
  • Do building occupants repeatedly change thermostat and other settings?
  • Are health symptoms such as muscle cramps, heat rash, severe thirst and fainting being reported?

Control MeasuresWork Environment2

Actions to help to maintain appropriate levels of temperature, airflow and relative humidity include the following.

  • Measure temperature, airflow and relative humidity in different parts of the workplace, either regularly or continuously, and record the results.
  • Monitor temperatures, ventilation rates and relative humidity over a period of time and adjust building services accordingly.
  • Set thermostats at appropriate levels and check them regularly.
  • Regularly inspect, maintain and clean heating, cooling, ventilation, humidifying and dehumidifying equipment and ducts.
  • Provide drinking water, free from contamination, easily accessible by all workers, clearly labelled, either in a fountain or with cups.
  • Where extreme weather conditions affect the internal environment, adjust settings on building services, and make individual fans and heaters available.
  • Respond promptly to reports of health problems.


Workers in some environments may be vulnerable to risks presented by the nature of their work. These will include:

  • People who work in hot, humid environments especially if they have to wear protective clothing
  • Those who work in chilled and refrigerated environments, where work is of a dirty nature, or where microbial, biological or chemical contamination is a possibility.

All employees in these situations should be trained to understand the risks, the symptoms and how to take action to protect their own safety and health. Such actions will include:

  • Drinking sufficient water
  • Wearing the appropriate personal protective equipment
  • Taking sufficient breaks
  • Washing hands thoroughly
  • Using showers where appropriate.

Disclaimer: The information provided through Legislation Watch is for general guidance only and is not legal advice. Legislation Watch is not a substitute for Health and Safety consultancy. You should seek independent advice about any legal matter.

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