4. cost reduction
5. fi nding a way through unforeseen events and 6. the humanization of work
working in small spaces (stairs, ladders). Long-term lifting and carrying loads cause changes in the joints of the legs more than when doing jobs in other body positions during work.
Figure 4.17 shows the body positions when carrying loads.
Figure 4.17 Body positions during carrying loads
In the US, a quarter of all registered occupational injuries are injuries of the lower back. Of these, 75% of the injuries occurred during lifting of loads and 20% when pushing or pulling loads. In the UK, more than a quarter of registered industrial injuries were caused due to handling, transporting or holding the loads. The proportion of injuries is as follows:
• back 45%
• hands 22% and
• arms 13%
The approximate values of ergonomically acceptable weight loads are shown in Table 4.7.
Table 4.7 Approximate values of ergonomically acceptable weight loads.
Table 4.8 shows the ratio of fatigue during lifting or lowering of loads from various heights.
Poor work habits are as follows:
i. Unsafe reach of loads
ii. Improper lifting and lowering of loads iii. Manipulate with very heavy loads
iv. Failure to use personal protective equipment
There is an increased burden on the spine when lifting or carrying higher loads or when handling loads with the spine in a curved or rotated position, because the muscles must support the weight of the body with the additional burden of arms. The forces on the spine also increase with the increase in horizontal distance between the load and the spine. According to the European Agency for Health and Safety at Work, the risk of back injury increases during lifting, carrying, pushing and pulling loads, if the load is:
Table 4.7Approximate values of ergonomically acceptable weight loads. Activities
Men Women Below 50Over 50Below 50Over 50 PeriodicallyOftenPeriodicallyOftenPeriodicallyOftenPeriodicallyOften Lifting with two hands; compact burden; close to the body300210240140180130140100 Lifting with one hand; compact burden; close to the body20014012080120807050
Table 4.8The ratio of fatigue during lifting or lowering loads from various heights. The load that should be lifted or lowered in N Ratio of fatigueto 4949–9898–147147–196196–245245–294294–343343–392 to 0.40 m0.240.250.270.300.330.360.400.44 0.41–0.80 m0.180.200.230.260.300.340.380.44 0.81–1.20 m0.150.170.200.240.280.330.390.46 1.21–1.60 m0.150.170.200.250.300.370.440.54 1.61–1.80 m0.170.190.220.270.340.420.52-
• Too heavy – There is no precise weight limit that is safe. Weight of 25–30 kg is tough for most people, especially if the loads are handled several times per hour. Pushing or pulling loads creates smaller burden on the body than lifting or carrying.
• Too big – One of the basic rules for lifting and carrying loads is to keep the load as close to the middle of the trunk of the body as possible. In order to keep a wide load close to the body a worker has to spread his arms to catch and hold it. When the arms are outstretched the arm muscles cannot generate the strength as effi ciently as when the arms are held closer to the body. Therefore, the muscles will get tired faster during handling, which demands widespread or outstretched arms to hold a large, huge load.
• Diffi cult to catch – When the load is hard to catch then the load can slip or move suddenly. Catching the load is more diffi cult with gloves than with bare hands.
• Placed in a way that it can be handled only with outstretched arms or by bending or twisting of the body. Lifting the loads with arms outstretched requires more muscle power/strength. If when lifting the load the trunk bends or twists, back injuries can easily occur.
• Sharp edges or the shape of the material can injure workers, especially in case of a crash.
When handling loads one must abide by the laws prescribed in that country.
At the international level the standard ISO 11228-1, Ergonomics - Manual handling - lifting and carrying applies. Directive 90/269/EEC - manual handling of loads provides health and safety requirements for the manual handling of loads where there is a risk of back injury for workers. The Directive sets out the following general obligations of the managers:
7. avoiding the need for manual handling of loads
8. taking necessary organizational measures to reduce the risk unless manual handling can be avoided
9. enabling workers to receive adequate information on load weight and 10. providing appropriate training and accurate information about the
proper handling of loads
The basic rules for handling loads are as follows:
1. Before lifting the load the condition of the load and the weight of the load should be checked.
2. The position of the foot should allow a stable posture.
3. Choosing the best position and do not change it during transport.
4. Heavy loads should be carried by two workers or use transport.
5. Women and young people should not lift loads over 15 kg (Table 4.9).
Table 4.9 Allowable load weight according to the age of employees.
Age of employees (years)
Maximum allowable load weight (kg) Men Women
from 15 to 19 35 10
from 19 to 45 50 25
more than 45 40 15
6. When carrying long loads on the shoulder the front part should be lifted in the air so as not to injury other workers.
7. Workers should be lined by height if carrying long loads on the shoulder.
8. Lifting of loads should be done from a crouch.
9. The loads should be accepted as close to the body as possible.
10. Lifting loads heavier than 4.5 kg in the sitting position is not advisable.
11. Lifting loads heavier than 20 kg in the standing position is not advisable.
12. None should be allowed to carry loads heavier than 55 kg.
13. It is necessary to avoid movements of twisting the spine, especially when the load is balance-deployed.
14. When carrying loads keep the spine in an upright position whenever possible, without bending and distortion.
15. It is necessary to break the operation of carrying into simple movements with short stops (more short breaks to 1 min) between two movements.
Figure 4.18 shows ergonomic of carrying loads (bundles) by lifts in the appropriate trolley.
Figure 4.18 Carrying loads in lift
Pushing a load requires about 15% less energy than pulling it behind (Fig.
4.19). A trolley should always be pulled a little sideways. Hands on a trolley should be about three feet above the ground and about 4 cm in diameter (Fig.
4.20). A trolley should have to lower the center of gravity and be as close to the axis as possible, to keep the balance and minimize the hand load.
Figure 4.19 Transport
Figure 4.20 Trolley
Characteristics of environments can particularly increase the risk of injury or diseases of the spine during manual handling, if:
a. There is not enough space to perform the job, especially if the space is of insuffi cient height.
b. The fl oors or the surfaces of work are uneven, due to which there is a danger of tripping or are slippery in relation to the shoes an employee uses.
c. Workplace or working environment prevents the safe load position in relation to the body of an employee or the position of the body of an employee.
d. There are differences in the level of the fl oor or the working surface because of which manual handling of loads is performed at different heights.
e. The fl oors or work surfaces are unstable.
f. The conditions of the work environment are inadequate.