For this assignment, the purpose was to investigate the causes of different postures resulting from

the unloading process from a car boot. The investigation also looked at the outcomes of these

various postures and comparisons were made between them and the predicted MAC tool usage.

Unloading heavy items from a car boot can be very awkward and often very tricky at times. Some

good examples could be the unloading of a sofa from a truck. Or removing a washing machine,

which although is very basic in shape, the weight of the washing machine is notorious for causing

back injuries or similar that could leave the user paralysed. It seems that for both the sofa and the

washing machine, designers tend to overlook the ergonomic features of these two items when it

comes to handling. Whether it is because certain criteria have been missed out or not remains to be

seen, but NOT proving any necessary grips WOULD be in breach of health and safety standards of

the products being sold.

There is an infinite number of ways in which different postures are created. This includes the angle

at which the user’s back is bent at, positioning of the arms, grip types, facial expressions, etc. Of

course, to get the full details of each individual image, high quality images are needed. This will

involve the use of two persons, one who is carrying out the unloading task, and another who is

carrying out the photography. An iPhone 5, which uses an 8 MegaPixel iSight camera will be use d in

HDR mode to ensure that every detail is fully captures on the images. The unloading area from which

the unloading task will operate on is a fiat Punto.

BEFORE the actual observation is undertaken, a MAC risk assessment needs to be undertaken and

EXCLUDE ANY TASKS RATED RED. The purpose of this MAC risk assessment is to see which tasks,

postures etc are considered dangerous. It is also worth noting that any ethical requirements are to

be included. Such criteria are that the user is NOT to be forced into carrying out the task if they do

not wish to do so, and that the user’s BMI is in line with the overall size of the mass to be carried.

Dimensions

On this page, we will look at some dimensions which revolve around the user, the microwave, the

unloading area and the car boot.

USER

Stature: 1650mm Mass: 60kg Experience with the task? __________________

Arm Span:1600mm Age:16

CAR BOOT

ENVIRONMENTAL CONDITIONS

The microwave will be picked up in cold conditions (5 C®) at about 6pm during a cloudy dry evening.

SURFACE

The surface on which the user will unload the microwave onto is chipped concrete.

PERCENTILES OF USER

Stature: 1650= 1745+Z(69) Z=-1.38 Weight: 60=83.5+Z(18) Z=-1.301 Hip Breadth: 355= 345+Z(29) Z=0.345

Assessment On this part of the assessment, we will look at the unloading area and the microwave to examine any hazards that could arise from the lifting of the microwave. Having sufficient space and weight distribution among the user is critical to ensure a smooth operation that is free from any RED tasks. To begin with, there are some risks present on the microwave. One of them is the cable, which could get tangled up with the user and cause them to trip up. Also, the tips of the pins might also harm the user depending on where they are located. The image below explains this.

The stands on the microwave might also be a risk to the user because they might agitate the user and cause them to drop the microwave. But then again, the chances are that the user might hold the microwave from the bottom, because it is wider than the height of the microwave. See image below.

The mass of the microwave is 16kg. The average human being would normally weight around 70kg, so this shouldn’t be a problem. Also, the person who will be lifting the microwave has a fairly stocky build, so the user shouldn’t be deterred from carrying a microwave. See image below.

Assessment – Predicted postures and hand grips

There are several different ways in which the user may react to the lifting of the microwave oven. The posture is very important, particularly when various types need to be identified for safety reasons. Below is a range of different postures that could occur. Initially, when the user starts to pick up the microwave oven, posture is likely to be symmetrical and bent at the same time (Pheasant, 1991). See image below.

When the user starts to pick up the microwave oven, the posture then becomes more asymmetrical (Pheasant, 1991). See image below.

The user may start to get very uneven as soon as their posture straightens up. See image below.

Posture may now be straighter and the spine may be stiffened up. See image below.

The user may have to take great care when handling the microwave because their arms will begin to fall out of line with their legs. See image below. The arrow indicates some side twisting.

Ideally, this would be a safe position for the user to relax their spine after a rotat ional twist on the spine. See image below.

After the user has taken a break, there is going to be a combination of flexion and torsional loading. It has been found also that the hips tend to lead, the lumbar the spine and musculature is exposed to high levels of loading here (Pheasant, Haslegrave, 2004).See image below.

When adopting this position, it may be advisable to hold the microwave from the side as it has been suggested by Pheasant that any load less than 300mm in width or from back to front should be held within the knees as the microwave’s height is 280mm.See image below.

This here is the safest position for the user because they are not as exposed to any spinal injury. This is provided that the user has bent legs in this picture. Here, increased flexion of the lower limb will be at it’s greatest here (Pheasant, 1991). See image below.

After placing the load on the ground, the user should take great care that they stand up because the spine may have to adjust to carefully contracting back into position. See image below.

Image Descriptions

Upon the user beginning to lift the microwave, the user seems to look fairly relaxed. This could imply that the user is starting to carefully grip on to the microwave. With referral to Pheasant’s analysis, the distance between the centre of gravity of the mass and the floor will be close to about 1 metre (Pheasant, 1991). This would be considered a safe task because the user is not picking the microwave up from the floor and the user’s legs are spread out, so overall, the weight lifting looks symmetrical and balanced. See image below.

Now, in this image, what we can see here is that tension looks as though is is starting to develop. Note how the right foot is in front of the left foot. It has been found that this could be a form of avoidance of trunk inclination and an avoidance of spinal flexion (Pheasant, 1991). It seems that in this image the weight distribution is largely being placed on the right foot, which is going to be sturdier and stronger than the spine. See image below.

The user is now trying to carefully lift the microwave out of the car boot. Because the actual lifting operation is taking place, the user may be thinking about trying not to bump his head on the cover of the car boot. This is where human instincts would tell the user that this could cause a hazard while lifting the microwave. For this particular lifting operation, the force in the spine, as suggested by Pheasant would be roughly 26N (Page 281, 1991). This is well under the maximum permissible limit, so this would be a safe operation. See image below.

The user for the first time in this lifting operation is straightening his back. This would be good for the user because it follows a diagram which shows the correct position for lifting cubed objects. This diagram can be found on page 297 of ergonomics, work and health, 1991 by Pheasant.See image below.

This image is similar to the above, but the user is turning his head to locate a safe unloading position. This would be deemed safe because the user otherwise wouldn’t know a good spot to unload the microwave onto. However, this could also be unsafe because of the torsion of the user’s spine. But the spinal loading is going to be below the action limit, as suggested by Pheasant 9Page 281, 1991). See image below.

In this image, the user is beginning to turn around to unload the microwave. This is where the greatest risk is likely to develop because there tends to be higher instability and greater torsi on here. However, this may be compensated for by increased intra – abdominal pressure, which has been found to be upward pressure on the diaphragm and downward pressure on the pelvic floor (Pheasant, 1991). See image below.

In this image, there is some similarities to the image above in that the same posture is used, but this time there is going to be pressure on the Thoracic of the spine, which has been found to be the longest section of the spine (Pheasant, 2004). Furthermore, the user looks as though he is leaning slightly to the left, so this would be an asymmetrical posture, it has been found (Pheasant, 1991). See image below.

In this image the user is now placing the microwave on the floor. The user would have taken great care when carrying out this operation because he is bending over quite significantly. This would be considered an inverse stoop lift, where a stoop lift has been found to be bad (Pheasant 1991), but because the user is unloading the microwave in a fairly uniform fashion and because his knees are bent, this would reduce lifting stress. See image below.

In this image, the user releases the microwave. This will relieve any pressure exerted on the spine when the user lets go. Also, the spine may contract to it’s original posi tion. Because the user is aaged 16 years old and has had no past problems with significant back injury, this would not be a problem. Studies by Adams and Hutton say that disc prolapsed would only occur during periods of extreme flexion (1982). See image below.

Finally, when the user straightens his back, he is unharmed and is able to rotate his neck. If this were not the case, he would be rubbing his back and showing expressions that he is in pain, which he isn’t. See image below.

Analysis – HSE Manual Handling regulation code comparison In order to ensure that the handling operation was smooth, analysis must be undertakn to ensure that any specific health and safety requirements were met. To begin with, comparisons will be made with the HSE manual handling regulation code, which has been found to be a leaflet outlining any necessary requirements for health and safety. On the first paragraph, of ‘What’s the problem?’ on page 1, the leaflet states that this is manual handling at work. The user being asked to unload the microwave oven from the car boot had undertaken the task of lifting just one microwave in one turn, which would simply not be the case in a labour intensive work station, or a non labour intensive work station, so one lift in a day in a ve ry long time would not count as ‘work’. On the second paragraph stating ‘What should I do about it’, there is one highlighted sentence stating what the user should consider. In the experiment undertaken, the user did have some consideration for his safety when he looked around to make sure that there weren’t any obstructions present and he did seem confident about his own safety when he slowly moved his feet and torso, so perhaps common sense might be better. The HSE leaflet asks questions such as ‘Does a large work piece really need to be moved or can the activity be done safely where the item already is?’ If the user were to move a work piece that had a greater BMI or mass or both than the user, then the user may wish to consider seeking help from a friend or from a removal company. On the paragraph titled ‘Controlling the risks’, it asks the reader what risks they should consider, i.e risks which might affect other people around them. It was found that there were no other people in close range of the person undertaking the task, other than the person taking the photographs. If the probability that the user was to come into close range with another person, the chances are that this would be 1 in 100 because you would take into consideration the people that live around the task being undertaken, and any outsiders, e.g couriers, postmen, builders etc. Between pages 5 and 6 on the HSE on the HSE leaflet, it mentions that the person carrying a heavy object should think before handling a heavy object and adopt a stable position. The user did both of these. Also, the user had to ‘get a good hold’, which meant the user had to hold his hands underneath the microwave. On page 6, a diagram showed how a cubed object should be held, which is how the user held the microwave. There was another diagram which stated that the user should keep his head straight whilst walking with the object. Because the user was simply picking up and moving the microwave from the boot to the floor, there wasn’t any carrying involved. On page 7, the leaflet mentions that an upward force that is 2% of the load being carried needs to be applied, provided that the surface is even. In the case of the experiment undertaken, the floor was slightly cracked, but it was highly negligible because it did not affect the user in any shape or form. Finally, the user moved the microwave very carefully and smoothly, while taking note of the fact that he was carrying a heavy object.

Analysis – MAC Comparison

Before the MAC tool was used to evaluate the lifting task, predictions were made on how the various postures would be made by the user. These postures predicted would have to be complimented with the various tasks provided by the MAC tool.

On some of the drawings provided in the predictions section, the microwave oven looks largely out of proportion with the actual size of the microwave oven. This may hide some of the features of the body such as the hand and possibly the torso. Some of the more significant images are shown below which best correspond to the MAC tool: The first image was fairly accurate because the user had his legs bent, but the user looks restricted. See image below.

In this image, and throughout the task, the user’s arms were above his knees. See image below.

On the 5th image, the user was found to have a straightened back and slightly bent legs, the user’s upper arms would also be vertical. There also seems to be little or no twisting. See image below.

Where MAC tool may have removed this task, the user could have struggled. The user looks like he is going to fall over. See image below.

After the MAC tool was used, the lifting operation had to be undertaken. This was where, in the space of 10 seconds, the user had to unload the microwave from the car boot and place it on the floor behind him. On one or two of the images, the user looks as though he is struggling. This may be because he is trying to get used to the fact that he is lifting a 16kg object that has the potential to trip him up if the cable gets him tangled up. On the first image, the user’s lower arms are clearly above his knees, so this would be regarded as safe. See image below.

In this image, the user’s upper arms seem vertical, so this would be compliant with the MAC tool. See image below.

This is where there seems to be twisting and slight side bending. See image below.

It could be argued that the surface looks uneven, but the user seems content with the surface he is working on. See image below.

There are some differences and similarities between the MAC tool before and after it’s usage. There is a similarity between the first postures in the predictions and the outcomes. Note how the user in the prediction has his head bent over and in the outcome, this person had his head bent over. The turning postures are also very similar, except the person in the predictions isn’t looking around to see where he is going. There is another difference, where the actual person doesn’t bend sideways, which is potentially hazardous.

Conclusions

For the MAC assessment, I believe that this was a well documented assessment that met the requiremetns shown on the flow diagram. It seems that the outcome of the lifting assignment was far better than what was predicted byu the MAC assessment. On the first task of the MAC assessment tool, it was obvious about the weight of the microwave because the weight was shown on the dimensions page, so the load weight task would obviously be amber. For the hand distance from the lower back, this was predicted to be amber because the user would have to bend forward to lift the microwave. However, this was not the case and the user found that he could straighten his upper arms. As this was also shown on the drawings in the predictions , the elbows were above the knees as the weight in it’s moving position is 76cm above the ground. For trunk twisting and sideways bending, this is more serious, so it would have been expected that there would be either of the two. But upon the actual outcome, there was little or none of the two. Based upon the findings from the health and safety recommendations, I do not believe that any regulations would need to be applied to the microwave when it is being lifted in one go. Using probability to estimate the chances of hitting someone by accident would have been quite far fetched, as the user was only moving the microwave within a short space of two metres. If one was to ever move a microwave on a daily basis, there would be a much wider variety of different postures and therefore the person undertaking the lifting task would HAVE TO CONSIDER how he/she is going to lift a heavy weight. The user is always going to have to think before he/she undertakes the unloading task, otherwise the user could sustain serious injuries. It therefore makes sense that the user adopts a stable position. To sum this up with a few words, the experiment proved a success, but it goes to show that ultimately, responsibility is placed on the user as long as they understand the task, the issues etc.

References

Stephen Pheasant, Christine M Haslegrave, 2004, Third Edition. Bodyspace. Taylor & Francis Group Stephen Pheasant, 1991. Ergonomics, Work & Health http://www.hse.gov.uk/pubns/indg383.pdf