Thursday, 17 December 2009

Noise: just a nuisance or damaging to your health?

Noise can be a nuisance affecting your concentration and causing you to get annoyed, i.e. noisy neighbours, roadworks or passing vehicles; disrupting your relaxation, reading, watching the television or sleep. However noise, particularly in the work-place, can actually have a severe impact on your health, causing temporary or permanent damage to your hearing. Also, working in high levels of noise can impact general safety, by interfering with communications particularly safety warnings for example fire alarms.

Under the regulations of the HSE Noise Regulations 2005 there is a duty for employers to protect the hearing of their workers.

A risk assessment must be carried out to determine the levels and duration of noise. Action must be taken to reduce the exposure to noise by choosing quieter equipment and machinery, installing noise dampening insulation wherever possible or provide different types of hearing protection.

The noise must be assessed using the following criteria:

• Is the noise intrusive i.e. similar level to a busy street, a vacuum cleaner or a crowded restaurant for most of the working day?
• Do your employees have to raise their voices to carry out conversation when approximately 2 metres apart for at least part of the day?
• Are your employees engaged in using or being in close proximity to noisy powered tools or machinery for more than 30 minutes in a day?
• Is your industry noisy, i.e. construction, demolition, road repair, textiles, engineering, forging, pressing, bottling, canning or paper manufacture?
• Are their impact noises; hammering, drop forging, pneumatic drilling or explosive sources such as cartridge operated tools, detonations or guns?

How is noise measured?

The measurement unit for noise is decibels (dB). An ‘A-weighting’ ‘dB(A)’ is used to measure average noise levels and a ‘C-weighting’ ‘dB(C) measures peak, impact or explosive noises.
A 3dB increase in noise level is generally noticeable but in fact doubles the noise level, therefore relatively small differences in the numbers can be significant.

Typical Noise Levels

Action Levels and Limit Values

Certain actions must be taken when the levels of exposure are averaged over a working day or working week and also the maximum noise (peak sound pressure) to which employees are exposed to in a working day.

There are two values:
• Lower exposure action values
o Daily or weekly exposure of 80dB
o Peak sound pressure of 135dB
• Upper exposure action values
o Daily or weekly exposure of 85dB
o Peak sound pressure of 137dB

There are also levels of noise that must not be exceeded
• Exposure limit values
o Daily or weekly exposure of 87dB
o Peak sound pressure of 140dB

Reducing noise levels

There are ways of reducing noise levels and exposure, redesigning the workplace and the work patterns can be useful.

• Use quieter processes and equipment
o Can you do work in some other quieter way?
o Can you replace whatever is causing the noise with something less noisy?
o Introduce a low-noise purchasing policy for machinery and equipment
• Introduce engineering controls
o Avoid metal on metal impacts e.g. line impact points with rubber or reduce drop heights
o Dampen vibration on machine panels
o Use anti vibration mounts or flexible couplings
o Fit silencers to exhausts and nozzles
• Modify the paths by which noise travels through the air
o Erect enclosures around machines
o Use barriers or screens to block the direct path of sound
o Position noise sources further away from workers
• Design and layout the workplace to reduce noise emission
o Use absorptive materials within the building to reduce sound reflection i.e. open cell foam or mineral wool
o Keep noisy machinery away from quiet areas
o Design the workflow to keep noisy machinery out of highly populated areas
• Limit the time spent in noisy areas
o Halving the time in a noisy area will reduce noise exposure by 3dB
• Maintain the machinery
o Have a planned maintenance schedule
o Replace worn parts immediately

Hearing Protection

If the noise levels cannot be reduced to a level that is acceptable then hearing protection must be issued to employees. Once issued it is mandatory to ensure that they are used properly. Hearing protection zones must be indentified and clearly marked. The employees must be trained and given information on how to use them and care for them.

There are some do’s and don’ts listed below:

• Make sure that the protectors give enough protection – aim to reduce levels to 85dB at the ear
• Target the use of protectors to noisy tasks in a working day
• Select protectors that are suitable for the environment in which they are being used – consider how comfortable and hygienic they are
• Think about how they will be worn and interact with other protective equipment (hard hats, respiratory protection and eye protection
• Provide a range of protectors so that employees have a choice on what is suitable for themselves.

• Provide protectors that cut out too much sound – this can cause isolation or lead to an unwillingness to wear them.
• Make the use of hearing protectors compulsory where the law does not require it.
• Have a blanket approach to the use of hearing protection - it is better to target its use to where it is needed.

There are different items that can be used for hearing protection:

Ear plugs are inserted to block the ear canal. They may be pre-moulded (preformed) or mouldable (foam ear plugs). Ear plugs are sold as disposable products or reusable plugs. Custom moulded ear plugs are also available.

Semi-insert ear plugs which consist of two ear plugs held over the ends of the ear canal by a rigid headband.

Ear muffs consist of sound-attenuating material and soft ear cushions that fit around the ear and hard outer cups. They are held together by a head band.
Different levels of protection are available it is important that you choose the correct level.

All hearing protection should comply to the following EN Standards:

EN352-1 Muffs and Headband
The section of the standard deals with head fasteners and establishes requirements in terms of manufacture, design and performance, test methods, instructions relating to marking and information intended for users.

EN352-2 Plugs and Bands
This part of the standard also deals with individually moulded ear plugs and devices connected by bands

EN352-3 Muffs and Helmet mounted
The present section of the standard stipulates requirements in terms of manufacture, design and performance, test methods, instructions relating to head fastener marking and information intended for head fastener users, when the latter are fixed on protective industrial helmets.

Ranges of hearing protection products including Peltor and Sordin brands are available on the Granite Workwear website under Ear Protection and Forestry Tools and Accessories; they offer various levels of protection covering all uses.

Wednesday, 9 December 2009

Tree Felling the Safe Way

Basic Felling

This is a short guide to the felling of trees in areas where there is a clear space of at least two tree lengths clearance in all directions and therefore there is no need for pulling aids to ensure that the tree does not drop onto other trees nearby.


Before commencing this task a risk assessment should be carried out and any operator must be appropriately trained in the use of the chainsaw and how to carry out the basic tasks, for more detailed information on this subject please see the article Using a Rear Handled Chainsaw published on 11th November 2009 on the Granite Workwear web site.

Included in this risk assessment should be the prevailing weather conditions, particularly high winds.

Make sure that all the correct tools are available, these may include a breaking bar, a range of sizes of alloy or plastic wedges, a sledgehammer and a hand winch complete with a handle, strops and a cable. Wherever possible plan to minimise any manual handling by the use of the appropriate tools.

It is also important to remember that felling a tree is a one man operation and to ensure that no other operator or machine is within two tree lengths. Survey the site to ensure that there are no underground or overhead services nearby, including electricity, telephone, sewerage, water or gas.

The felling operation

Inspect the tree thoroughly to ensure that there is no dead wood, insecure branches or noticeable signs of decay. Decide on the direction you want the tree to fall and make sure you have a suitable escape route with no obstructions.

Remove any debris from around the base of the tree, and also any obstructing vegetation that may impact on the operation taking particular care that the dispersal of the exhaust fumes from the chainsaw are not restricted.

Remove any low branches ensuring that that you are protected from kickback by keeping the guide bar out of line with your body, also it is useful to use the stem for protection, never use the saw above the height of your shoulders.

Make a sink cut to make a hinge this helps control the rate and direction of fall. A sink cut is a triangular shaped cut with a horizontal base and a 45° angle placed in the direction that you want the tree to fall, it should be the depth of a quarter of the diameter of the tree and the top and bottom cuts must meet exactly with no overcut to damage the strength of the hinge.

Start the felling cut at or very slightly above the level of the bottom sink cut, as you make the cut be careful of the tree moving and trapping the blade. The felling cut must leave a hinge of at least 25 mm at right angles to the direction of fall. If the blade does jam switch the chainsaw off and then pull gently to try and disengage it, if it cannot be freed then use appropriate tools to open the cut slightly.

It is important to remember that once the felling cut has been started then the tree must not be left, the felling must be completed.

Once the felling cut has been completed then use a breaking bar to to lever the tree over, always remember to keep your back straight and use your legs to lift, also keep both hands on the lever.

When the tree starts to fall immediately step back and to the side into your pr-planned escape route always be aware that the butt of tree may rebound as the tree falls.

After the tree has been safely felled you can then commence the snedding operation to remove the limbs that were too high to reach when the tree was standing.

Crown Breakdown

Breaking down the crown of a large tree can be very dangerous, you should always be ready for the tree rolling or for the branches springing back when cut.

To ensure the tree does not roll the use of a properly anchored winch is required. Ensure that you have a clear escape route at all times and plan the work sequence so that this is possible. Ensure that there are no bystanders in close proximity. Never work underneath any part of the felled tree, if it moves you will be crushed.

While working continually assess the tension in the branches, especially those that are in contact with the ground and thereby supporting the main stem.

Cut away the smaller branches first retaining the main supporting branches, again never work above shoulder height. When tackling the larger branches ensure that any debris from your previous cuts has been cleared from the ground to ensure you have a secure footing. Always keep assessing any potential movement of the tree.

If the branches are large cut them down gradually rather than going straight to the stem. Once you have cleared the branches to shoulder height, use the winch to roll the tree in a controlled manner to bring the remaining branches to a safe cutting height. When you have cleared all the branches and the tree is in a stable sate you can de-limb flush to the trunk.

The Granite Workwear Site offers a large range of PPE specifically for forestry work including clothing, footwear, head, eye and ear protection, along with a number of articles similar to this one, if you have any questions please do not hesitate to ask us.

Wednesday, 2 December 2009

Fall Arrest for Arborists

Falls from height are the single biggest cause of workplace deaths and one of the main causes of major injury, this applies across all industries. By nature of the work, arborists often have to climb to high points and unlike the construction industry often it is difficult or impossible to use working platforms or scaffolding.

Therefore the most practical way of ensuring safety is the use of personal fall protection equipment i.e. a fall arrest harness, for example the Komet Miller Dragonfly and Butterfly II harnesses on the Granite Website in the Forestry Tools & Accessories section.

The regulations applicable to this subject are The Work at Height Regulations 2005 (as amended) obtainable from the Health and Safety Executive.

Fall arrest systems are designed to limit the impact force of a fall and ensure that the user cannot hit the ground. The anchor point must be as high as possible above the feet of the user thereby limiting the distance that they can fall.

Of course the anchor point must be strong enough to hold the impact force of the faller, taking into account the distance and the weight of the person. Always check the condition of the tree and suitability of anchor points before committing life and limb.

There are a number of actions that must be taken when using this type of equipment as explained below.

Risk Assessment

Work at height must be properly planned and organised and should take into account weather conditions, all personnel must have received appropriate training and be competent and healthy.

They should also have read the manufacturers product information literature.

Wherever possible try to minimise the height from which a person can fall and be fully aware of the consequences if they do fall.

All the work must be supervised, never carried out alone.

Selection and maintenance of equipment

The equipment being used must be suitable for the task being carried out, within the design limits. It must comply with BS EN 361 for a full body harness. All components being used must be compatible with each other.

All equipment must be checked even when new and then before each use to ensure that it operates correctly and that it is in good condition. The checks should be both tactile and visual, passing the equipment slowly through the hands to feel for cuts, abrasion or any contaminants as well as softening or hardening of the fibres. Ensure that the visual checks are carried out in good light conditions, also do not hurry these checks, your life may depend on it...

In addition to the pre-use checks a more comprehensive check should be carried out by a trained and competent person on a regular schedule and these checks should be documented. Particular attention is required where the equipment can come into contact with acids or alkalis.

Any damaged equipment must be taken out of operation immediately, even small cuts or abrasions will have a serious effect on the performance.

If the equipment has become wet in use it must be dried thoroughly before storing it in clean dry conditions.

Action to be taken in case of a fall

This topic was covered in the article Aerial Tree Rescue published on 9th November 2009 but we feel that it is important to bring attention to the risk of Suspension Trauma which is little understood by most people even though it has been known about for quite a few years.

It is a natural reaction in the body to being held in an upright position with immobilised legs. Normally the use of leg muscles helps to return blood to the heart, if the legs are immobilised which would be the case in using a fall arrest harness, this process starts to fail and blood starts to pool in the legs, this causes the brain to receive less blood and starts to be starved of oxygen. Loss of consciousness can occur in less than 6 minutes. Research has suggested that death can occur in as little as 10 minutes. If the fall has been caused by a trauma like a bad cut or a head injury then this timescale can be more rapid.

Suspension is therefore a life threatening situation and urgent rescue is needed within 10 minutes. However when the accident victim is rescued certain things have to be considered.The blood that has pooled in the legs contains toxins, which if released into the circulation could damage internal organs and in extreme cases stop the heart from beating. This is known as Reflow Syndrome and traditional first aid techniques could be fatal in this case. Casualties must not be laid flat at any time in the rescue or when on the ground. The casualty should be kept in a sitting position with their legs either straight out or pulled up to the chest for a minimum of half an hour even if they are unconscious.

It is important that all workers know of the dangers of the risks of Suspension Trauma and the correct techniques for handling it, anybody who has been suspended for more that 3 minutes should be treated as if they have it.

Of course prevention is always better than cure and all measures to reduce the risk of falling should be employed wherever possible, including regular breaks to reduce fatigue and the use of the correct protective clothing to reduce heat stress.