1. Lighting

Lighting has a significant effect on work efficiency, comfort and safety. Although our eyes can adjust to a wide range of brightness, efficiency and safety will deteriorate unless workers can clearly see what they are doing.

No one will challenge the need for proper lighting. Nevertheless, there are great variations from one factory to another in the lighting levels during similar operations. There are many workshops where better lighting can improve productivity and reduce accidents.

Proper lighting varies according to the tasks that need to be performed. Fine work requires stronger lighting than other kinds of work. Lighting which is adequate for simple loading or heavy manual work will not be satisfactory for machine or office work. Fine finishing or painting, assembling or inspecting of small parts, drawing offices, and manipulation of dark objects require much higher standards of lighting. On the other hand, glare from too bright light sources should also be avoided, as it could lead to eyestrain. Strong reflections can also hamper work. Sudden shifts in illumination, as in the case of moving from areas of strong daylight to poorly lit areas, can result in accidents. It is particularly important that older people have plenty of proper lighting.

Proper lighting needs a good combination of daylight conditions and artificial lights. There are many means of improving lighting at low cost. Installation of skylights or wider window openings can greatly help. Relocation of worksites in relation to windows or light sources is sometimes helpful. The adjustment of the height or re-positioning of light fixtures can often make a great deal of difference to lighting. Using light colours for walls and fixtures should be considered. Provision of local lighting or spot lights, especially for operations which require higher lighting levels than others, can often be done at relatively low cost. Simple measures such as regular cleaning of windows, lamp-shades or lamp-covers and replacing old lamps or flickering fluorescent light tubes are also important.

Prevention of direct or reflected glare can be achieved by a change in the light direction towards the worker or by the use of adequate shades for the light sources.

Many examples of low-cost improvements in lighting can be found in developing countries. One advantage is that the enterprise, once aware of the need, can carry out improvements in lighting relatively easily. The cost of such improvements per worksite is usually low. The examples in this section also show that improvements in lighting can lead to a noticeable improvement in work efficiency and the quality of products.

Case 36: Installing skylights

In a furniture-making factory in the Philippines, workers complained about the inadequate lighting facilities. The manager also noticed that work was hampered by the poor lighting. The management installed a number of skylight roofing sheets made of clear polyvinyl chloride among the galvanised roofing sheets. There was a marked improvement in the quality of finished products. There was a noticeable reduction in the re-work rate in the factory. There were no more complaints about the lighting from the workers.

The cost incurred was about US$ 150 which was mainly used for the materials. The skylight sheets were installed by the workers. The work was completed in a week by two workers (average wage, US$ 4 per eight-hour day).

Figure 63: Skylights installed in a furniture factory.

In another tile-manufacturing company Which employed about 20 workers in the Philippines, the workplace was enclosed with concrete walls with few openings. It had been designed that way to prevent sawdust from spreading to the neighbouring residential houses. The manager and his son discussed a plan on how to provide adequate lighting. They had two options to choose from. One was to add ten fluorescent lamps to illuminate the whole area sufficiently. The other was to install six skylights on plastic transparent roofings to enable the natural sunlight to enter the work area.

They eventually decided to install six skylights instead of lamps to save their electricity bills. The six Skylights were installed on two sloping sides of the factory roof. As a result, there was a considerable increase in lighting. About 15 of the total 20 workers benefited from the improvement. The cost for plastic roofings was US$ 35 with the cost of installation at about US$ 11. Considering the electricity and maintenance costs of fluorescent lamps, the installation of skylights proved to be more economical.

Case 37: Fibre-glass skylight sheets

In a big workshop in Calcutta, lamps were placed near the ceiling so as to make enough space for the operation of an overhead crane. As the illumination in the workshop was poor even in the daytime, some skylights were installed. Corrugated fibre-glass transparent sheets were fitted into the roof at four different places directly above the areas requiring more illumination. As a result, the workers had fewer complaints of eyestrain, and safety also improved.

The approximate cost of the fibre-glass sheets was US $55 for 20 square feet and the fitting charge was US$ 5. The costs saved cannot be assessed but the savings in electricity bills amounted to US$ 10 per month. As the electrical lights required less use, there was also a 30 per cent reduction in the costs of replacement of the bulbs.

These two examples show the remarkable improvement in lighting which would result simply by making better use of daylight. Skylights cannot provide enough lighting at all times of day but can contribute to increased illumination levels and savings in electricity bills.

Case 38: Painting the walls white

In a pump-manufacturing factory in Madras, lighting inside the workrooms was found insufficient for work. The reason was not clear to the manager. Sufficient tube lights hanging from the roof had been provided. There were corrugated plastic sheets over the roof at intervals to let in daylight. On careful examination, however, it was noticed that the hanging tube lights were covered with accumulated dirt. The clear plastic sheets were also covered with dirt and sacks. The workers thought the sacks was necessary because of sunlight glare during the summer. It was also noticed that the ceilings and walls were dirty and therefore proper reflection of light was hindered.

It was decided to remove the dirt and the sacks, and to paint the ceilings and walls white after thorough cleaning. All the tube light fittings were cleaned and the underside of the reflectors was also painted white. The ceiling and walls were given two coats of white paint. When this was completed, the factory looked entirely new and there was adequate light for the workrooms.

The white paint for the ceilings and walls cost nearly US$ 220. The cost was small in view of the large benefit in increased production. The workers were happy as eyestrain and discomfort at work were notably reduced.

Figure 64: Both ceilings and walls painted white.

In another small workshop producing electronic equipment parts in Madras, general lighting was also poor. The windows and doors and their north-facing glass should have been sufficient for general lighting in the daytime, but the walls, windows and doors were all dirty. Hence it was decided to clean all the walls and windows and to give the walls a coat of primer and two coats of white paint. As a result, the general lighting conditions improved remarkably. Productivity increased slightly with less complaints of fatigue from workers. The total cleaning and painting cost was US$ 350. The cleaning charges per month were estimated to be US$ 10.

Figure 65: Skylights and windows cleaned and ceilings and walls white painted.

Case 39: Lowering lights

The sewing and knitting sections of a garment firm in the Philippines, with about 65 workers, were affected by poor lighting. Women workers at the sewing and knitting sections on the second floor, and male workers at the knitting section on the ground floor complained of low levels of lighting. The rather high rate of rejected knitted and sewn products seemed in part to be related to the poor lighting. When a foreman talked with the workers, they pointed out the very high positions of fluorescent lamps. There were six pairs of fluorescent lamps on the ceiling of the knitting section, but they were too high and not adequately located in relation to the workers' positions. Using sixty metres of wire, the fluorescent lamps at the two sections were lowered and relocated at more appropriate positions.

The cost incurred was only as US$ 15 for 60 metres of wire. It was no longer necessary to install more lamps. There were no more complaints about eyestrain due to poor lighting. Productivity increased by five to ten per cent.

Figure 66: Fluorescent lights arranged for each workstation in a knitting section.

Figure 67: Lights lowered to an appropriate position to give more light on knitting operations.

Case 40: Repositioning lights with new reflectors

In a fitters' workshop of an engineering factory in Burma, bad illumination was considered to be a factor in causing some accidents and also bad workmanship. The workers complained of visual discomfort. The production manager who surveyed the illumination with a photometer found that the low level of illumination was due to the distance between the existing four overhead lights and the workbench. These four-foot fluorescent lights were without reflectors and fitted on a single overhead hanger.

Figure 68: A 40 W fluorescent light in the fitters' shop.

The positions of the lights were lowered by about 30 cm so that they were about 130 cm above the workbench. This height was found to be optimal as the lights were kept beyond the visual angles of the workers. The lights were fitted on two parallel overhead hangers in a zig-zag pattern. All were fitted with proper reflectors. Approximately US$ 150 was spent on refitting the lights with reflectors. Electricians among the factory staff fitted the lights on the newly arranged overhead hangers.

The illumination measured prior to modification was 130 lux at the workbench height. The improvement resulted in raising the illumination level to 280 lux. The management and the workers agreed that the improvement was satisfactory and reduced risks of injury.

Figure 69: Modified positions of fluorescent lights provided with proper reflectors.

Figure 70: A worker working under the repositioned light with an illumination level of 280 lux.

Case 41: Improving lighting fixtures

The owner of a shoe-making factory in the Philippines, which employed 80 workers, discovered that there was a need for more adequate lighting in its production area of approximately 350 square metres. The workers were asked to specify how lighting in their individual workstations could be improved or modified. Several lamps were found to be either broken or flickering. Some workers complained of fatigue, headache and eyestrain due to inadequate lighting.

With the help of an electrician, the owner made a plan for modifying the lighting arrangements taking into account feedback from the workers. About 20 new fluorescent lamps were installed in place of incandescent bulbs and broken or flickering fluorescent ones.

Reflectors were then fitted into the fluorescent lamps using available materials such as hard cartons and aluminium foil. The light fixtures were lowered to a level appropriate for production work. In most cases, this level was about 30 cm lower than the original height. Instructions were given to the workers to keep the lighting units clean.

After these improvements, the production increased by about 10 per cent on average. The repetitions required decreased by about 25 per cent. Over 90 per cent of the firm's workers considered that the additional fluorescent lamps and other changes undoubtedly reduced their discomfort.

The cost of the twenty units of fluorescent lamps, three rolls of aluminium foil and wood attachments and the labour cost of an electrician and carpenter amounted to approximately US$ 65.

Similar improvements of fluorescent lamp fixtures were made in a small pinewood furniture manufacturing company with 27 workers, also in the Philippines. With the assistance of a stock clerk, the owner-manager consulted the workers about better lighting. They agreed to install reflectors for each of the 25 fluorescent lamps. These reflectors were made of plywood, aluminium foil, tapes and wires. The cost incurred was minimal, approximately US$ 30. The workers felt more comfortable and the increase in their efficiency was estimated to be approximately 10 per cent.

Case 42: Better lighting for an assembly plant

An assembly plant making electronic products in Singapore with 240 people working in two shifts undertook a better lighting scheme in a section of about 180 square metres. This was because several workers of the section had complained of visual discomfort and the rejection rate of assembled sets was quite high.

After a survey of illumination levels and glare and shadow problems, the lights were modified in the following three ways. First, the light covers were cleaned, which led to a significant improvement. Second, the overhead lights were lowered to an optimal height to give good illumination, no glare and no interference with bodily movements. Third, defective lights were replaced with new ones. As a result, an average increase of 20 per cent was noted in the number of assembled sets for every shift, and there was average decrease of 15 per cent in the number of rejected sets per shift. The workers agreed that eyestrain was reduced and comfort increased.

The costs incurred were approximately US$ 500, including lights and labour costs. Since the lights were installed during the weekends when there was no production work, there was no interruption of work during the modifications. Savings from increased productivity far outweighed the costs.

Figure 71: Typewriter assembly operations which require good lighting.

Figure 72: Overhead lights lowered to an optimal height over assembly lines.

This example underlines an important point. Lighting can be improved considerably by modifications in the position and maintenance of lights, and production work, such as assembling small parts, can benefit a great deal from these inexpensive modifications. For similar reasons, lights should be maintained on a regular basis.

Case 43: Glare and lack of contrast

In an electrical assembly plant in Sri Lanka, the lighting from fluorescent light tubes was quite adequate. The work tables were varnished and polished and covered with thick white paper. The walls were light yellow. The components assembled were white or pale yellow. The problem here was glare and lack of contrast of colours. The management covered the table surface with black paper and repainted the walls pale blue. The results were encouraging. The rejection of assembled parts fell by 15 per cent and production increased by 10 per cent. The cost of the improvements came to US$ 120.

Case 44: Reducing injury risks by adding lights

In the section of an engineering factory in Burma where a grinding machine was located, six cases of a foreign body in the eye were reported within a period of three months. The existing general illumination level was found to be only 60 lux, with the light coming from a transparent roofing sheet somewhat distant from the machine. With this low illumination level, the workers did not use the protective eye-glasses provided which were dirty and scratched.

The situation was improved by fitting two additional sets of 40 W fluorescent lights over the machine. The illumination level was raised to 260 lux. New protective eye-glasses were provided. It was also found that the workers who used the machine did not know how to close properly the shutter at the top of the hood guard. The workers were instructed on the use of the shutter which helped prevent dust from escaping. The management agreed to install in the future a standard exhaust system for removing dust.

The two new sets of fluorescent lights cost US$ 140. There were no more complaints of visual discomfort. When the safety committee checked the work station three months after the modifications, the workers were keeping the shutter closed and wearing safety glasses at work. No cases of a foreign body in the eye were reported after the improvement.

Figure 73: An operator working without protective glasses and with the shutter at the top of the hood guard in an open position.

Figure 74: Work at the grinding machine with a newly fitted light. The operator is wearing protective glasses and the shutter is in the closed position.