Created on: 14 Jul 2023

Inadequate lighting at work can lead to eye strain, fatigue, headaches, stress and accidents.

The amount of light is not the only factor as badly designed lighting systems give rise to glare. This can cause stress and headaches, as well as creating accident risks.

Heavy contrasts can be dangerous as moving between bright to very dark areas can cause temporary blindness as the eyes adapt.

Lighting Problems

Common lighting problems found at work include:

  • dark or unlit areas, especially near hazards such as machines or steps;
  • lack of natural light because of dirty or badly placed windows;
  • glare from badly positioned or poorly shaded lights or windows and reflecting surfaces;
  • energy saving programmes leading to cuts in lighting levels;
  • workers suffering eyestrain or fatigue from bad posture caused by poor lighting;
  • dirty or poorly maintained lighting, leading to light loss, and flicker;
  • unsuitable decor, leading to lower light levels, excessive contrasts or too much glare; and
  • security risks at night caused by poor lighting outdoors.

Lighting problems at work can be investigated in a number of ways:

  • asking workers - although many people get used to bad lighting;
  • using a light meter to check against standards (see below); and
  • looking for glare or asking for a full lighting survey.

Measuring Light

The level of light is measured in “lux”. Interior levels are very much lower than outdoor natural light. Some typical light levels are:

Very bright summer day

up to 100,000 lux

Overcast summer day

30,000 to 40,000 lux

‘Bad light stops play’

1,000 lux

Shady room in daylight

100 lux

Street lighting

20 lux

The amount of light can be measured by a light meter.

These are readily available, though many photographic light meters are not calibrated in lux.

The employer’s duty to ensure the health, safety and welfare of employees under HASAWA includes a duty to provide adequate lighting to ensure that work can be done safely and employees’ health or eyesight is not damaged.

The provisions contained in MHSWR, especially Regulation 3, risk assessment, are also relevant. Regulation 8 of the Workplace Regs states that employers must ensure that:

  1. every workplace has suitable and sufficient lighting;
  2. this should be natural light, so far as is reasonably practicable; and
  3. suitable and sufficient emergency lighting shall be provided where needed.

The Regs do not define “suitable and sufficient” but the ACoP says that the lighting should enable people to work and move about safely and will be dependent on the tasks to be performed and hazards to be negotiated. Where natural light is utilised, windows and skylights should be regularly cleaned, although they may be shaded to reduce glare and heat.

If emergency lighting is necessary for reasons of safety, it should be powered by an independent energy source to the artificial lighting. Lighting should be sufficient to enable people to work, use facilities and move from place to place safely and without experiencing eye-strain. Outdoor areas should be adequately lit after dark.


Lighting levels may be adequate but glare from a direct source or light reflected off equipment or paper can cause discomfort. Glare is light in the ‘wrong place’ and there are three different kinds.

All can cause strain and fatigue and some may interfere with vision:

  • disability glare can dazzle and impede vision, and so may be a cause of accidents - one example is the effect of full-beam car headlamps;
  • discomfort glare is more common in work situations - it can cause strain and fatigue, especially over long periods, and is caused by direct vision of a bright light or background; and
  • reflected glare is bright light reflected by shiny surfaces into the field of vision - its effects can be the same as those for discomfort glare.

The best way to spot the effect of glare is to identify places where a light source shines directly or by reflection into the operator’s vision. It can be harder to spot glare from light fittings when day light is present as well.

Then see if screening, shading or fitting diffusers on lights makes any difference. To reduce glare the following steps should be considered:

  • adjust shades, screens or reflectors to reduce direct views of light sources;
  • raise the light fittings (if suspended);
  • fit diffusers around the light sources (especially if fluorescent);
  • check that the right size and type of bulb or tube is being used;
  • reduce the number of reflective surfaces in the workplace;
  • re-site the working positions to reduce glare from windows;
  • redecorate to avoid heavy contrasts, especially between windows and dark walls, and ceilings and light fittings;
  • fit shades or blinds to reduce glare from windows;
  • alter the position of fluorescent light strips so that they are viewed end on;
  • make sure that desk lamps are properly positioned and screened; and
  • be careful that the light brightness is not unacceptably reduced in attempts to tackle glare - simply cutting light levels is not enough.


It is important to get lighting arrangements right at the design stage for example when new work layouts are being planned. Some key principles are:

  • use natural light as much as possible - most people prefer it, but windows need to be well sited and kept clean; light levels fall away rapidly as you move further from a window, so extra lighting will be needed for some parts of rooms, even in daylight;
  • position fittings carefully to make the best use of light while avoiding glare;
  • consider room decor - light ceilings and walls make the best use of light - avoid heavy contrasts;
  • provide local lighting (such as desk lights); and
  • emergency lighting may be required by law for the workplace - it may be specified in the fire certificate; emergency lighting is powered from batteries or generators; batteries need to be placed in a well-ventilated room and the system must be regularly checked and tested; illuminated emergency exit signs should also be checked.


Even well designed lighting systems will not perform properly unless well maintained. Dirty fittings can produce a light loss of 20%. Old fluorescent tubes can lose up to half their brightness before they fail. Bulbs lose 10% brightness before failure.

Old light units are less economical because they use the same current to produce less light. It is better to replace lamps in a group in all but small lighting systems. This can be more economic and less disruptive than replacing individual units as and when they fail.

A regular cleaning programme for fittings is also sensible.