DSE Assessment

Kevin Brown
Member - 110 posts

A recent Canadian study concluded that slouchers were probavly right all the time. I've not seen anything cascade into European thinking on DSE yet. If and when it does it will be interesting to see how the new study is received. I think the article I read was in FM World, several months ago.

Tony Williams
Member - 31 posts

Surprisingly enough, we are not all the same shape, and different people naturally adopt different seating positions. If you try to force everyone to adopt a standard seating position you will cause more problems than you will solve.

The approach I take is that if someone is comfortable let them continue in that position. If they are getting back or upper limb symptoms, they may need to alter position or use additional equipment to help. For many, it is important to vary the position through the working day.

If I see someone who is adopting a particularly awkward position I will point out that most people would get symptoms if they did that, and that the person could consider adjusting their position if they started to develop symptoms.

Be warned, if you tell everyone they must adjust their chair to 10-15 degrees and they have chairs that will not adjust, some will develop symptoms purely for psychological reasons, and these symptoms are the hardest to treat.

You also need to realise that some companies make a lot of money marketing 'ergonomic' bits and pieces that in most cases are completely unnecessary. I have also seen many ergonomist reports recommending a swathe of specialist equipment that is very expensive and quite uncalled for (for example someone who was visually impaired was sitting forward in a awkward posture to read paperwork and see the screen, and developed back pain. An ergonomist recommended an electrically adjustable desk, special keyboard and mouse, wrist rests and ergonomic chair when what they actually needed was a reading aid and a larger monitor).

The simple solution is to ensure that employees who sit to work have adjustable seating, and allow them to adjust the seat to suit them. Make sure the seating is correctly maintained, and suitable for the task. Most office chairs have a maximum safe weight of 18 stone...

Tony

David Sharp - Workplace Law Network
Online advisor - 134 posts

This is a really interesting question Colin. I’m sure you’ll already be familiar with the Health and Safety (Display Screen Equipment) Regulations 1992 (as amended by the Health and Safety (Miscellaneous Amendments) Regulations 2002) – and the guidance that accompanies them.

If you haven’t had chance to read it, it’s worth taking a look at the Workplace Law Network factsheet on DSE: http://www.workplacelaw.net/news/display/id/10529. You’ll need to be logged in to access it.

Schedule E to the 1992 regulations refers to work chairs. It states:

• “The work chair shall be stable and allow the operator or user easy freedom of movement and a comfortable position.
• The seat shall be adjustable in height.
• The seat back shall be adjustable in both height and tilt.
• A footrest shall be made available to any operator or user who wishes one.”

Neither the regulations not the approved guidance specify an angle at which to set the seat back. The HSE says merely that workstation equipment (including chairs) should comply with BS EN ISO 9241 Part 5: workstation layout and postural requirements. So ultimately any decision over what is an ‘ideal’ angle is more subjective.

The intention behind having an adjustable seat back is to allow as best as possible the weight of the trunk to be spread as evenly as possible so as to reduce stress on the spine and the 100 or so muscles that support it. Whether and how this is actually achieved is going to depend on a lot of factors, not least the sex, size and shape of the person, but also their own posture – how many times do we all see people with ‘perfectly’ adjusted chairs who are sat on the edge of them crouching over their laptops.

So to an extent I would say: don’t get too hung up on the angle of chair backs.

That said, we have come across references to unattributed recent studies which suggest it is better to set the chair back at an angle of 100-110 degrees to the legs, as opposed to the more traditional 90 degrees – the more traditional wisdom you referred to.

Research conducted by Woodend Hospital in Aberdeen in 2007 goes as far as to recommend a 135 degree angle as optimal (though it appears only to have considered three variants: ‘slouching’ forwards; 90 degrees, and 135 degrees). The study concluded that:

“Disk movement was most pronounced with a 90-degree upright sitting posture. It was least pronounced with the 135-degree posture, indicating that less strain is placed on the spinal disks and associated muscles and tendons in a more relaxed sitting position.”

It’s worth a look at the report on the study: http://www.futurepundit.com/archives/003919.html. There is a strong argument that any great move away from the vertical (90 degrees) might improve the mid to lower spine, but might end up putting more pressure on the neck and upper spine.

You might also find our recent Briefing for Workplace Law Network members of interest: it’s called ‘Are you sitting comfortably’, produced for us by RF Chairs: http://www.workplacelaw.net/news/display/id/11616.

I hope this is of help, and please let me know if you have any feedback on this answer or from your colleagues assuming you are revising your DSE policy/procedures.

Nigel DuPree
Member - 170 posts

Intention and outcome are, of course, two disperate fings like the old joke about 'Naval Intellegence' and oximorons.....

The very best of intentions will fail when "fatigue" has it's way with any of us and we are no longer able sustain performance and productivity let alone maintain a good ergonomic posture after a prolonged period sat at the ubiquitis screen.

So, take a break, do something else, have a good yawn, in fact anything that will get you breathing, blinking and moving in order to distract and/or de-stress the system ready to go again...

Screen Fatigue remains the biggest risk factor in RSI type MSD's as you start to squint a little and lean into the screen to accomodate fuzzy double vision before the head, neck, shoulders and back begin to ache.

Join the self-preservation society and look after yourself.

John Ewing
Member - 4 posts

Is self assessment suitable for carrying out dse requirements

Andrew Graham-Cumming
Member - 14 posts

I have not seen the research mentioned, but it is hardly new. A detailed study was made by Keegan - Keegan JJ. Alterations of the lumbar curve related to posture and seating. J of Bone and Joint Surgery 1953; 35A:589-603. There was also work by Akerblom and Mandal in the 50s and 80s respectively looking at optimal seat back angles. As a generalisation, andgles of about 105-110 degrees are appropriate. A seat back angle of 90 degrees will produce unacceptable lumbar disc compression in most people.

The 135 degree angle comes from the dynamics of the rotation of the pelvis as the hips flex. Starting from upright, as the hip flexes to 45 degrees (ie a back to thigh angle of 135 degrees) the muscles at the back of the thigh become tight. Further flexion causes the pelvis to begin to rotate, which in turn flattens the lumbar spine. When the hip is flexed to about 90 degrees the lumbar curve becomes flat (subject to individual variation). Further hip flexion causes reverse curvature in the lumbar spine. The effect of a flattened lumbar spine is to compress the front of each lumbar disc, increasing the pressure in the disc and pushing the pulp of the disc backwards. This in turn puts spinal ligaments in tension and can impair local blood supply. Hey presto! postural back pain.

The 135 degree angle is the normal angle in horse riders - hence the good posture that girls who ride horses usually have.

A seat with a 135 degree angle is rarely practical in an office, although some people find those strange kneeling things comfortable.

Charles Buckton
Member - 7 posts

John,

The self assessment would only be the first step to assessing the individuals work station. Depending on the type of self assessment you use, this will determine if the employee has an inherent problem or not enough information to set up there workstation correctly. This will then help you decide what can be done.

However, you should also look at employees who come back with a near perfect score as well, as most people tend to treat them as a tick list and dont want much envolvment. You may want to look at involving your IT department as they should help lead something like this as most of the issues I seemed to get back were IT related.

There are also a number of different websites (if you need them) that can help with how to aset up a workstation correctly. However, as it has already been mentioned above, most people tend to adjust these to suit there own needs and comfort zones.

Nigel DuPree
Member - 170 posts

Therein lies the problem somewhere between "apathy" & "denial" unless, of course, you are the person currently suffering a "subjective" and/or very real health issue symptomatic of DSE operation and then, and only then, do a small proportion become bothered to address it until or unless it becomes serious enough by which time the damage may done........

So, perhaps it is time to develop a more proactive and "objective" approach to DSE Risk Assessment, one that is a little less dependent on subjective and reactive self-reporting of problems experienced by the user.

The existing approach hasn't worked even after the introduction of legislation designed to protect and mitigate the risk reported by 58% of users or is it a straight cost/benefit issue ?

If it is then perhaps management needs to get their head around the potential 20% reduction in performance associated with Screen Fatigue that represents around 33 days lost production per annum !

Makes sickies and absense management look a little sick doesn't it ?

Stuart McRae
Member - 1 post

When sitting at a workstation the most important things are that you use a chair that firstly fits the individual using it. The chair must adjust and must be easy to adjust by the user and anyone else that uses the chair. The chair must also have sacral support and not lumber support. tilt the top of the hips forward while in a comfortable seated position and the lumber will not colapse (as when in a standing posture). Once the sacral area is stabalized then the lumber region of the spine jjust needs to be supported as people have different.


As I said the chair must suit all users so the front edge of the seat must be adjustable (not a sliding seat as some manufacturers use as this can simply cause people to move there backs away from the backrest as these products tend to use moulded foam seat pads). Idealy the chair should not have any faom and fabric either for thermal comfort as fabric and foams hold heat and are not exactly hygenic!

The chair should also allow the users to recline on the chair while still supported but not beyond 137 degree as they may go to sleep!!. By leaning back on the chair you need to open and close the body angles at the hips, knees and anckles

These are the very general things that we should be looking for in office seating. The existing 1992 legislation is so out of date it is a joke to be honest.

Carrying out DSE Assessments on people who dont have a product they can actually sit on properly that is designed with a human element is pretty pointless.