Temperature, humidity, ventilation and lighting are major determinants of comfort in the workplace. Departures from satisfactory conditions can have harmful health effects. These hazards are covered by the Workplace Health, Safety and Welfare (WHSW) Regulations 1992, which come fully into force on 1 January 1996. They replace sections of the Factories Act and Offices, Shops and Railway Premises Act.

The Regulations cover all workplaces, except ships, moving vehicles, mines, quarries and building sites. This factsheet describes the legal requirements and good conditions for the protection of comfort and health for temperature, humidity, ventilation and lighting (see also Daily Hazard No. 30 for a factsheet on hot working conditions).

Temperature

(WHSH Regulation 7). The law requires only that a reasonable temperature shall be maintained in indoor workplaces during working hours. There is neither a maximum nor a minimum temperature specified in the new legislation; the minimum temperature specified in the old legislation has now been abolished. Fixed heating systems should work such that injurious or offensive fumes, etc. do not enter the workplace. Portable heaters should not produce harmful or offensive fumes. Combustion heaters must have a sufficient air supply for complete combustion.

The Regulations require a sufficient number of thermometers to be available to enable the temperature to be measured throughout the workplace. The Approved Code of Practice (ACoP) says thermometers need not be in every room.

There is advice in the ACoP stating the minimum temperature in workrooms should be 16 ^oC, or if severe physical effort is required, 13 ^oC. This advice does not apply where it would be impractical to maintain such temperatures, e.g where food is being kept cold. There is no advice on an appropriate maximum temperature.

The Chartered Institution of Building Service Engineers (CIBSE) has published design criteria for temperature in buildings used for work. CIBSE recommends a range from 13 ^oC for heavy work to 20 ^oC for sedentary work. The World Health Organisation recommends 24 ^oC as the maximum temperature for working in comfort. Beyond this dehydration, heat stress and ultimately heat stroke can occur. Cold temperatures affect dexterity and mobility and may increase physical and visual strain, with added problems for people with muscular pain, arthritis and heart conditions.

The maintenance of a comfortable temperature should be a matter of local negotiation and agreement. This should cover matters such as providing air cooling plant, siting workstations away from sources of radiant heat, the provision of local heating or cooling, insulation, shading windows, the provision of hot or cold drinks, and entitlement to suitable protective clothing or rest periods.

Where necessary, suitable systems of work should be introduced to limit exposure. A maximum and minimum go-home temperature should be introduced at which workers can stop work and/or leave the workplace. There is no legal right to leave the workplace as a result of extremes of heat and cold, unless there is serious and imminent danger.

Humidity

There is no specific legislation dealing with humidity, apart from in humid factories, but its proper regulation is essential for comfort in all workplaces. Humidity is the amount of moisture in the air; at saturation point the relative humidity is 100%. Low levels of humidity can exacerbate respiratory and skin conditions. There may also be a build up of static electricity in dry air resulting in electrostatic shocks. For most applications, the relative humidity should be between 40% and 70%. Carpeted buildings with underfloor heating need relative humidity towards the higher end of the range. Humidifiers, intended to moisten the air must be properly cleaned and maintained if they are not to become a source of bacteria and moulds.

Ventilation

(WHSW Regulation 6). The law says only that every enclosed workplace must have effective and suitable ventilation which provides a sufficient quantity of fresh or purified air. Ventilation equipment must give an audible or visual warning when it fails where there is a health and safety factor. The Regulation applies to general ventilation but not to local exhaust ventilation which is dealt with by other legislation.

Fresh air is needed for respiration, to dilute and remove impurities and odours and to dissipate excess heat. The build up of impure air, along with other environmental factors, can result in sick building syndrome, whereby occupants suffer respiratory and other illnesses.

In many cases, windows or other openings will provide sufficient ventilation. If they don't mechanical ventilation should be introduced. Replacement air should be free of impurities as far as possible. Air inlets for ventilation should be sited where they can draw in fresh air; they should therefore not be sited near any source of fumes or other impurities.

Recirculated air (e.g. in air conditioning systems) should be adequately filtered to remove impurities. The purified air should have some fresh air added to it and systems should be designed to allow this to happen. Mechanical ventilation systems should be regularly and properly cleaned, tested and maintained. According to CIBSE, the fresh air supply rate should not fall below 8 and may be as high as 25 litres per second per person depending on how crowded the conditions are and whether smoking is permitted. Steps should also be taken to ensure that workers are not exposed to draughts.

Lighting

(WHSW Regulation 8). The Regulations state that every workplace shall have suitable and sufficient lighting and that it shall, as far as is reasonably practicable, be by natural lighting.

Lighting should be sufficient to enable people to work, use facilities and move about safely and without experiencing eye-strain. Exposure to fluorescent lighting is associated with headache, eye-strain, eye irritation, fatigue and increased stress and accidents. Exposure is also associated with the onset of skin conditions and there is growing evidence of a link with the incidence of skin cancer. Some people become allergic to fluorescent lighting and more sensitive to sunlight. Flickering lighting may produce hyperactivity. A shortage of natural light can lead to seasonal affective disorder (SAD), resulting in a range of mental and physical illnesses.

Good lighting conditions involve:

maximum provision of natural daylight avoidance of fluorescent lighting where possible maximum control by individual workers of ambient lighting including the provision of desk lights and uplighters selection of suitable lighting for the task to be performed avoidance of dazzle and glare, by repositioning of lights if necessary and by the introduction of non-reflective surfaces suitable lighting for both indoor and external traffic routes suitable positioning of light switches immediate repair or replacement of all faulty lights, light fittings and cabling.

There shall be suitable and sufficient emergency lighting where workers are especially exposed to danger if artificial lighting fails.

Detailed guidance on the selection of a safe lighting system can be found in the HSE publication Lighting at Work [HS(G) 38, available from HSE Publications].

Action

Proper attention to temperature, humidity, ventilation and lighting lead to a safe, comfortable and efficient workplace. Employers commonly avoid their legal duties in this area as the laws are non-specific and very rarely enforced. Workers can protect their conditions by

keeping a record of unusual or excessive conditions carrying out regular inspections ensuring all ill-health attributed to workplace conditions is reported in the accident book calling in the enforcement authorities if extreme conditions persist organising through their union to demand satisfactory conditions are introduced ensuring employers also discharge their responsibilities to non-employees on their premises

Further information

The Chartered Institution of Building Services Engineers (CIBSE), 222 Balham High Rd, London SW12 9BS. Tel: 0181 675 5211. CIBSE publish documents on standards of lighting the workplace etc. which are useful to Safety Representatives negotiating workplace standards.

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