D. Staal Wästerlund and F. Kufakwandi
Dianne Staal Wästerlund was an associate expert on a technical assistance project executed by the International Labour Organisation (ILO) for the Zambia Forestry and Forest Industries Corporation (ZAFFICO). She is now based in Garpenerg, Sweden.
Frank Kufakwandi is Managing Director of ZAFFICO and was the overseer during the implementation of the ILO project.
Action taken to improve worker safety and productivity in response to studies carried out under a technical assistance project, supported by the International Labour Organisation.
Demonstration of appropriate felling techniques. Note the personal protective equipment
The parastatal Zambia Forestry and Forest Industries Corporation (ZAFFICO) was formed from the Industrial Plantations Division of the Zambia Forest Department with the help of a World Bank loan in 1982. Based heavily on plantations, ZAFFICO was established to help meet the increasing demand for timber in Zambia and to complement supplies from indigenous forests which were being overexploited. At the time of the writing, it had established 40000 ha of pine and 10000 ha of eucalyptus plantations and owned five sawmills (with a total installed capacity of 80000 m3 per year), a pole treatment plant, a joinery and other wood processing facilities.
This article examines studies of working conditions in ZAFFICO during 1988 and 1989, and subsequent efforts to improve the working environment. The development and implementation of a system for accident recording is also discussed. The intent of the article is not to focus specifically on a single forestry enterprise but rather to highlight challenges common to forest worker efficiency, safety and health in African developing countries while identifying opportunities for improvement. Many possible improvements would be applicable to other forest enterprises.
Forestry work requires a considerable amount of physical energy. Logging operations are particularly taxing, especially when performed manually or with chainsaws. Muscle strain or damage to the skeletal system (particularly the back) are common among forest workers. Another risk in tropical developing countries is heat stress which occurs when the combination of solar radiation and heat produced during work cannot be sufficiently dissipated. Studies were carried out on 119 workers of the Chichele logging team to determine if the physical workload in different operations was sustainable, to test alternative methods of distributing physical workloads and to indicate production levels that are achievable without the risk of health damage from an excessive workload.
Technical background
The performance of physical work requires muscle action and the muscles need oxygen to transform food into mechanical energy - a process called aerobic combustion. The more energy is required to perform a given task, the more oxygen is needed, this causes increased blood circulation and, consequently, results in an increased heart rate. Therefore, a physical workload can be estimated by measuring the heart rate during work, compared with the heart rate at rest. To be efficient in providing oxygen to the body, the average heart rate during work should not exceed 40 percent of the range between the individual worker's heart rate at rest and maximum heart rate under stress.
The heart rate range of each of the workers studied was determined using the Harvard Step Test. This is a standard measuring system in which the heart rate is measured during an initial period of rest, after a six-minute period of stress - during which the worker steps on and off a box of 40 cm in height at a rate of 22.5 steps per minute - and again after a seven - minute recovery period. The age, work experience and specialization and lifestyle habits (particularly smoking) are factored into the standard equation.
Heart rate measurement during work
The activities studied were the manual piling of match billets, the cross-cutting of logs with a chainsaw, tree-felling with a chainsaw, the debranching of trees with an axe and choker setting logs for hauling with a skidder. The study divided the examination of each activity into three steps. In the first step, the worker worked at a normal pace, avoiding unnecessary rest such as waiting time, talking to colleagues, etc. In the second step, the work method and pace were varied to consider the effect on the heart rate. In the last step, the worker was asked to work according to the most favourable method and pace, as determined in step two, for a full working day. In practice, this design proved too complicated to apply in a manner that guaranteed statistical validity. Unexpected interruptions were common and workers had difficulty in modifying their work habits and pace on command. The equipment used was a heart rate transmitter to which a portable radio was tuned.
A chainsaw operator using protective equipment
The results showed that felling with a chainsaw and debranching with an axe required energy expenditures that forced the heart rate well up over the 40 percent threshold, thus indicating that the standard working practices posed a potential risk of physical damage. In the case of felling operations, the normal working procedure was to work for a period of 30 to 45 minutes and then take a rest of 15 minutes during which the chain was sharpened and small repair work done. The introduction of short rest periods of approximately two minutes reduced the average heart rate to approximately the 40 percent level.
After felling, the trees are debranched and topped with an axe. For this job, it is possible to work on a continuous basis, unless chainsaw operators return to work on a strip adjacent to the debranching workers. Therefore, there are no "natural" rest periods in this phase of work. It appeared in the studies that workers proceeded at a pace that accumulated fatigue and pushed the heart rate well over the 40 percent threshold. During the experiment, workers had to repair the axe several times because the head was loose, but they never sharpened the axe and there was no whetstone available to do so. The sharpness of the axe has an important influence on both the productivity and physical workload of this operation. The introduction of predetermined rests of three and five minutes after the debranching of each tree had the effect of reducing the average heart rate to near the 40 percent threshold. Significantly, it appeared that these rests did not negatively affect overall productivity, as workers used the rest period to plan their work and movements in the working area better in order to avoid interference with heavy slash. However, it is noteworthy that the workers were not sympathetic to short rest periods (as opposed to fewer, longer breaks), as they had fewer opportunities for social contacts.
The study also compared production rates during the test exercises with those estimated for overall production. The differences were remarkable: worker productivity during the tests was vastly higher than during "normal" operations.
Although the short study periods tended to provide artificially efficient working conditions, there appeared to be ample scope for improvements in productivity.
As a result of the findings, a number of changes in working conditions were implemented. Tools and equipment are now being sharpened by a specialized group of workers, for instance. During the period when sharpening takes place, the main felling and debranching workers take short rests and recover from fatigue. Worker training in improved techniques and methods has been intensified to improve performance and reduce fatigue during logging operations.
Another change has been the provision of free lunches to all employees. This has resulted in a significant increase in worker productivity in the afternoon.
Finally, to capitalize on the evident potential for productivity improvements, a series of incentive schemes based on a bonus proportionate to incremental production above pre-set monthly targets has been introduced.
The overall impact of these changes in the Chichele working environment has been a respective 50 and 45 percent productivity increase in logging and sawmilling operations. There are also fewer accidents and reduced absenteeism. To ensure that productivity will be maintained at the higher levels, a Work Study Section has been established to review the situation on a continuing basis.
Repeated exposure to more than a certain level of noise can lead to a loss of hearing. The effect of noise on hearing capacity depends on the noise level, the length of exposure and the sensitivity of the individual. Noise emitted by machines has caused hearing losses in many forestry harvesting and processing workers.
The Kalibu circular sawmill was established in 1984 and has a rated capacity of 20000 m3 of sawn timber per year. Approximately 130 workers are employed at the mill. A study was conducted to determine the noise levels of the machines; indicate the workplaces where operators are exposed to noise levels that can cause hearing damage; and determine to what extent the hearing capacity of operators was actually affected by noise.
Theoretical background
Sound is a motion in the air that the human ear can detect. The properties of sound are loudness and pitch. The loudness of sound depends on the strength of the motions in the air. The fluctuation of air pressure caused by motion - called sound pressure - can be measured. A logarithmic unit, the decibel (dB), has been established to express the sound pressure level in relation to the threshold of human hearing.
The pitch of a sound is determined by the number of motions per second, i.e. the frequency. The human ear is not equally sensitive to all frequencies; low pitch sounds are perceived less than high pitch sounds of the same pressure. The weighted sound pressure level, dB(A), gives a reliable assessment of the subjective disturbance from noise.
To express the average noise level to which a worker is exposed during a working day (including scheduled breaks, various operations, etc.), the equivalent level of sustained noise Leq[dB(A)] is used. Internationally, a noise level of 85 dB(A) is regarded as the maximum safe limit for an eight-hour working day without ear protection. The ILO Convention No. 148, which Zambia has ratified, states that national laws or regulations shall prescribe that measures be taken for the prevention and control of, and protection against, occupational hazards in the working environment due to air pollution, noise and vibration (art. 1). According to the convention, national limits should be set for exposure to noise. In Zambia, the limit has been set at 90 dB (B. Mwemea, Senior Safety Officer, personal communication).
Mechanical extraction of logs from plantation to the mate logging road. Note the protected cabin
The convention states that the working environment shall be kept free from any noise hazards, by technical measures applied in the design or installation of new plants or processes, or added to existing plants or processes; or, where this is not possible, by supplementary organizational measures. If these measures do not bring the noise level within the specified limit, employers are expected to provide and maintain suitable personal protective equipment and inform employees of hearing damage risks as well as control and prevention measures.
Test methodology and results
As a first step, the purpose of the study was discussed with the managers of the sawmill and the workers were informed. Next, during the actual testing period, noise levels were measured at 30 places in the sawmill, using a noise dosimeter, at ear-level and at a distance of 1 m from the machines under load and at idle speed. In addition, workers at 13 places in the sawmill were equipped with noise dosimeters.
All measured workplaces showed noise levels above 85 dB(A) when machines were under load and all but two showed noise levels above the 90 dB(A) level set by the Zambian national insurance fund. Even with machines at idle speed, 14 of the 30 workplaces measured showed noise levels above 85 dB(A).
Determined on the equivalent level of sustained noise (Leq), the average noise level of the 13 places where workers were equipped with dosimeters was 93 dB(A), with actual noise levels ranging between 89 and 98 dB(A). Under these conditions, the maximum recommended exposure without ear protection during an eight-hour day would range from 0.4 to 3.3 hours, with an average allowable work period of only 1.4 hours.
In the sawmill, MSA ear protectors are available and, when used properly and constantly, could reduce the noise reaching the ear by 10 to 15 dB. However, not all operators were equipped with ear protectors and not all those who were equipped used them on a regular basis. Complaints such as "it's too hot" or "I can't hear when somebody speaks to me" were common.
The average length of exposure to noise for the employees who participated in the study was 5.1 years. According to the International Organization for Standardization, based on an average noise level of 93 dB(A), between 4 and 12 percent of the employees could be expected to show some loss of hearing. However, audiometric tests carried out on the 13 participating employees showed that 52 percent of the sample already had some hearing damage, ranging from a IS percent loss of hearing in one ear to the complete loss of hearing in one ear. No immediate explanation could be determined for this incidence of hearing damage but it highlighted the need for urgent action. Hearing impairment is irreversible and the loss of hearing capacity can be expected to increase over time.
Discussion
Personal protective equipment has played an important role in the protection of workers from occupational hazards in the forestry and wood industries. However, this equipment is mainly produced in Europe and North America and is designed with a temperate climate in mind. Under tropical conditions, it can be extremely uncomfortable. Studies are needed to determine how existing equipment might be adapted to tropical conditions and to consider the possible production of appropriate protective equipment from locally available materials in developing countries.
However, for some machines it would be insufficient to simply ensure protection of the worker, as the dimmed noise level would still exceed the 85 dB(A) limit. To reduce noise at the source, regular machine maintenance is essential. At least in part, the high noise levels recorded at the Kalibu sawmill were attributable to deficient maintenance resulting from limited hard currency and a lack of spare parts - a problem common to industrial operations in many developing countries. For example, the cover of the sawmill's slab edger was broken, significantly increasing the noise from the circular saws. There was also evident scope for adjustments in machine installation, the development of machine enclosures with damping material and the placement of workers in less noisy locations, particularly those who have already been exposed to excessively high noise levels.
Based on the results of the study, the corporation took steps to improve the station by stepping up maintenance of sawmill machinery. More attention has been dedicated to ensuring that workers have access to, and actually use, ear protectors. Supervisors and the safety officer have been sensitized to the need for greater attention to this aspect of work.
To confront the unacceptably high incidence of hearing loss, regular medical check-ups at the Pneumoconiosis Bureau are arranged for all workers. Those showing signs of hearing loss are redeployed within the organization.
The reporting of fatal and permanently disabling accidents has long been mandatory in Zambia. The Workmen's Compensation Board collects accident reports from all industries with the aim of determining whether the injured worker is entitled to financial compensation. In complying with these requirements, ZAFFICO submitted to the Workmen's Compensation Board an average of two or three accident reports per year. More recently, the Zambia Industrial and Mining Corporation (ZIMCO), grouping all parastatals, has shown an interest in safety in the workplace and has requested the submission of a quarterly report from all organizations. ZAFFICO therefore required a method for determining a complete picture of all accidents occurring and it was decided to develop a new accident recording procedure, with a form designed especially for the corporation.
Accident reporting in relation to accident prevention
The reporting of accidents may serve multiple purposes. A company interested in safety in the workplace can use accident recording as a source of information on current conditions. When accident prevention becomes a goal, the causes of accidents are the most important factors to be considered. In some accidents, the causes are obvious and immediate action can be taken. Others are less obvious; for example, fatigue, heat stress and lack of skill. Accident statistics can help identify these causes.
Accident recording needs to be detailed in order to be meaningful. A form that requires the reporting officer to use a specified format and provide a set amount of detail will be most useful. This is particularly important for subsequent analyses of the statistics, especially when they are considered by someone other than the initial reporter.
Development of the accident recording form
There are many model accident report forms available, including several that are designed especially for forestry work. However, as most have been developed for use in industrialized countries, many of them are very detailed and require considerable technical knowledge and a good analytical ability on the part of the reporter.
To be more appropriate in the circumstances prevailing at ZAFFICO, a simplified recording form was designed. The form requires inputs from the supervisor of the injured worker, the senior official and the safety officer. The supervisor provides basic data, the senior official comments on the cause as well as preventive action to be taken, while the safety officer is responsible for collating the data before transmitting them to ZIMCO and, when necessary, the Workmen's Compensation Board. This division was deemed appropriate for two reasons. First, it took into consideration the varying education levels in the organization. Second, the direct involvement of the senior officials was aimed at bringing them more into the realm of safety management and also at providing a link to top management, which is often unaware of safety problems except for those that result in particularly serious injuries.
To introduce the accident recording form and create more awareness at all levels about the need for safety in the workplace, five training courses were held and attended by 52 supervisors and senior officials, mainly from the plantation, logging and production departments. The courses covered the following items: causes of accidents; accident prevention; the role that accident recording could play with regard to prevention; and actual use of the new forms. Active participation in course discussions was encouraged.
The seminars were very rewarding. Many of the participants had experienced accidents at work and understood that the new form could be a valuable tool for accident prevention. Some of the senior officials expressed concern, however, that their limited knowledge of the technicalities relating to safety in the workplace would constrain their ability to propose preventive measures.
In an effort to impart safety knowledge to those directly involved in the implementation of sound safety programmes at ZAFFICO, all supervisory courses now have a safety input, including instruction on the proper use of the accident recording form.
As stated above, before the introduction of the accident recording form, all but the most serious accidents often went unreported. After the safety seminars, however, people realized the need to report every accident, regardless of its severity. Since 1990, about ten accidents have been reported per year.
Based on an analysis of the accident reports, there are three main causes of the accidents experienced in the corporation: environmental working conditions; human error; and defective machinery or equipment. Of all the accidents occurring, about 60 percent are a result of workers failing to observe specified working procedures. Twenty-five percent are the result of environmental working conditions and 15 percent are attributable to defective equipment or machinery.
To respond to this analysis, the corporation is now staging regular safety seminars for workers and supervisors to ensure that workers are aware of safety rules, to stress the need for adherence to safety procedures and to understand why workers are not following such procedures. In some cases, procedures have been modified to become more practical for workers to follow. In addition, efforts have been made to improve the working environment, including the physical placement and maintenance of machinery, to create a safer workplace.
To summarize, based on the results of the ILO - assisted studies, ZAFFICO management introduced a number of improvements to its working environment. The provision of free lunch resulted in significant increases in productivity after midday, particularly in the logging, production and plantation sections.
Even before the study on noise measurement and audiometric tests, ZAFFICO had provided workers with ear protectors. The study, however, evidenced the fact that simply providing equipment was not sufficient.
Workers needed to be informed on the benefits of wearing the protective devices and supervisors needed to be more involved in ensuring that protection was used. Moreover, there is a need to evaluate and perhaps redesign protective equipment to ensure that it is appropriate for use in the tropics.
ZAFFICO has dramatically stepped up the preventive treatment part of its worker safety programme. All workers are being sent for medical check-ups once a year and those with health problems are redeployed appropriately. Worker safety is now an important component in all internal courses run by the corporation at its Worker Training Centre.
By introducing the simplified accident reporting form, the processing of accident compensation has been made significantly more efficient. The analysis of accident causes has become a regular part of the operation, enabling management to take appropriate action to eliminate recurring problems.
The end result has been a substantial increase in productivity, a reduction in the number of accidents (although there has been an increase in the number of accidents actually reported) and an improvement in worker attitudes, as demonstrated by a sharp drop in absenteeism. Although there is still ample room for further improvement, the importance of worker safety and health is now an integral part of operations at ZAFFICO.
Staal, D. 1990. Zambia Forestry and Forest Industries Corporation (ZAFFICO). Final report on ergonomics and work study in forestry and forest industries. Based on a one-year assignment as Project ZAM/85/01/IDA associate expert. Geneva, ILO. (unpubl.)
