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July 3, 2005

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Breathing space

At Wolstenholme International’s manufacturing site in Darwen, Lancashire, around 90 employees are involved in the production and packing of speciality metallic inks, pigments, flakes and powders. Consequently, the company needs a range of solutions to help protect its employees from the potentially harmful effects of solvents and fine dust particles used and created during the processes. Jo Partridge explains how the company looks after the respiratory health of its workforce.

The gold and silver inks and pigments produced at Wolstenholme’s Darwen site create brilliant, novel and decorative metallic effects for products aimed at the consumer market. Typical uses of Wolstenholme International’s metallic inks and pigments include highly decorative grocery labels and packaging, brochures, magazines, cosmetics, as well as coat hangers, paints, coatings, and textile screen prints.

The functional properties of the metallic powders and flakes produced are used in the construction industry and in applications where conductive materials and thermostatic properties are required. For example, the combination of concrete slurry with aluminium powder creates the aerated concrete used in breeze blocks. Copper flakes are used in lubricants to prevent cold welding between machinery and engineering components, and to reduce ‘electrical noise’, or arcing between a carbon brush and commutator.

In producing metallic flakes, inks, pigments and powders workers apply three main processes:

* the bronze process, in which metallic flakes and pellets are created in a foundry and in ball mills;

* the inks process, in which metallic flakes and pellets are combined with solvents, toners and varnishes to create gold and silver inks; and

* the aluminium process, in which aluminium powders are produced.

Although the manufacturing processes are enclosed, dusts and vapours become airborne during filling operations. Respiratory protective equipment (RPE) is used to provide protection against the residual airborne hazards not captured by the local exhaust ventilation. The RPE is selected following a risk assessment and is based on the hazard encountered, its concentration, and the work being carried out. The preferences of workers are also considered where a choice of RPE exists.

Airborne menace

The human body has natural defences to many hazardous substances. Many others, however, if they are present in sufficient quantities, or are of a certain size, can bypass these natural defences and thus cause harm. Particulate hazards – for example, dusts with a particle size of between 0.5 and 5 microns – are invisible to the human eye and can go undetected by the body’s natural defences. If the lungs are unprotected against these harmful fine particles, they can reach the alveoli – the tiny thin-walled air sacs present in each lung, through which oxygen enters and carbon dioxide leaves the blood (gaseous exchange). Fine, respirable particles have the potential to settle deep in this area of the lung and, once there, can lead to long-term respiratory illnesses.

When solvent vapours are inhaled they will cross into the bloodstream and potentially go on to cause damage to other organs. The solvents used at Wolstenholme have good warning properties, so an air-filtering device with a gas and vapour filter was selected, the correct filter being matched to the hazard.

Workplace exposure limits

The solvents, dusts and gases within the three main processes all have differing workplace exposure limits (WELs). WELs are set under the Control of Substances Hazardous to Health Regulations (COSHH) and published in EH40 (a 2005 version was published in April to coincide with the changes in COSHH). WELs are the airborne concentration of hazardous substances averaged over a time period. They should not be exceeded and, for certain substances identified in EH40, exposure should be reduced as low as is reasonably practicable.

The WEL of copper is 1mg/cubic metre; the WEL of aluminium is 10mg/cubic metre; and the WELs of the solvents used at Wolstenholme range from 1 PPM up to around 1000PPM. During all the foundry processes, there is a requirement for workers to wear respiratory protective equipment. In the main, the company’s risk assessment requires a level of P2 protection, but some operations in the foundry require P3 protection. The three levels of disposable respirators available – FFP1, FFP2 and FFP3 – offer different levels of protection. FFP1s have an assigned protection factor (APF) of 4; FFP2s an APF of 10; and FFP3s an APF of 20. This means they may be used in concentrations of solid and non-volatile liquid particles up to 4 x WEL, 10 x WEL and 20 x WEL, respectively.

Masks for tasks

Wolstenholme’s health and safety manager, John Maynard explains: “We are always in the market to trial new and innovative developments in RPE. Twelve years ago we identified that, for some applications, in line with COSHH requirements, we could use maintenance-free respirators, which obviate the need for extensive records to be kept. Currently, we use a cup-shaped, valved disposable respirator and a foldable, un-valved disposable respirator to help protect workers from fine dusts and powders in the bronze, inks and aluminium processes.

“Each person has a different shaped face and varying comfort level requirements, so not everyone is suited to the same face piece. The valve on one respirator reduces heat and moisture inside the respirator, making it especially easy to breathe through. The other, foldable respirator allows employees to step in and out of a hazardous area, fold up their respirator and put it in their pocket for re-use on re-entry. Both are low weight, comfortable and compatible with other PPE, such as safety goggles. Workers pick up a fresh respirator at the beginning of each shift, and may use more than one per shift if required.”

For protection against gases and vapours in the solvents areas at Wolstenholme International, workers are provided with a maintenance-free gas, vapour and particulate respirator. The respirator is CE-marked and approved to EN405: 2001, Class FFA1P2D, and, provides protection against the effects of fine dusts, oil and water-based mists, and organic gases and vapours, with good warning properties. The respirator provides maximum usage limitations of: gases/vapours: 10 x WEL or 1000ppm, whichever is the lower; and particulates: 10 x WEL. It is designed to be re-usable, but should be disposed of when gas/vapour filters are saturated, or when the particulate filter clogs (whichever situation occurs first), or as dictated by the company respirator change policy. Many companies choose to discard this type of respirator after one month, even if it is in a good, usable condition, thereby avoiding the COSHH requirement to keep monthly examination records.

Following best practice

The health and safety of Wolstenholme’s workforce during process operation is paramount. Various steps are taken to ensure that employees are aware of the hazards present in the workplace and are aware of their health and safety responsibilities – both in the foundry and in the other workplace areas.

John Maynard explains: “COSHH assessments are undertaken on all materials used in the processes. The COSHH hierarchy for control of hazardous substances is used, i.e. elimination or substitution of the hazardous substance, engineering controls, e.g. containment/local exhaust ventilation, and the use of personal protective equipment (PPE). In reality, most situations require several levels of the COSHH hierarchy to be used in order to adequately control the risks associated with exposure to hazardous substances. The provision of PPE is rightly at the bottom of the COSHH hierarchy but nevertheless it plays an important part in controlling operator exposure to the particulates and solvents used on site. Workplace monitoring of operator exposure levels to hazardous substances determines that the correct type of RPE is specified, and all employees who are required to wear RPE are then fit-tested to ensure the specified respirator is suitable for them. If they fail the fit test an alternative but equivalent respirator is specified.

“There are other risks on site – in addition to those posed by hazardous substances – that need to be controlled. For example, there are noise protection zones within the foundry and milling areas where ear defenders are necessary. Noise Frequency Octave Band Analysis is undertaken to ensure that all hearing defenders specified give the required degree of noise attenuation across the complete spectrum of noise in each area defined as a hearing protection zone.

“Milling of the powders takes place in multi-stage milling systems, from which objects could fall, so hard hats are mandatory in these areas and others, such as storage areas, where a risk of head injury has been identified. In all areas where solvents are used, the safety goggles and impervious protective gloves are required to be worn.

“Employee training is seen as vital to ensure that RPE is worn correctly and at all times, when required. The philosophy behind this training is that if employees are aware of the risks of the tasks they undertake then they will make full use of PPE – in other words they will wear it because they understand the positive reasons for doing so, and not just because the company says so. A training matrix has been developed, which ensures that not only are all employees captured in the training programmes but that refresher training is given at specified intervals.”

Wolstenholme has invested in a multimedia software training package, which allows the company to develop PC-based training modules incorporating sound, image and video. The training packages are thus made site and process-specific and hence relevant to the tasks undertaken by the operators. The training packages also include a comprehension test at the end of the training. Operators are required to take the test to ensure they have understood the material in the training package. Only if they pass the test, usually set at a minimum of 80 per cent comprehension, will they be viewed as trained and competent to carry out the task.

Wolstenholme International is classified as a small to medium-sized enterprise and does not have a full-time occupational health physician. It has, however, sponsored a local general practitioner to undertake a post-graduate course in occupational medicine and the GP meets weekly with John Maynard to review health and safety issues. The GP will also review all absence certificates to ensure that possible work-related absences are investigated, and flag up any trends or concerns to the company.

Conclusion

Any company using RPE on site should implement an RPE programme to ensure it is used properly. This may sound time-consuming and some may question its return on investment, but taking a responsible and structured approach to RPE provision gives rise to short-term benefits in terms of worker satisfaction, as well as the long-term benefit of protecting employees from occupational injury or disease, and thus helping to reduce a company’s exposure to compensation claims.

An RPE programme is considered best practice by the HSE and, indeed, many of the elements of such a programme, e.g. training, fit-testing and maintenance, are already mandatory. Guidance on implementing an RPE programme is contained in the British Standard BS 4275 (available from the British Standards Institution) and HSG 53: The selection, use and maintenance of respiratory protective equipment – a practical guide, available from HSE Books.

 

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