Preventing Exposure to Asbestos Fibres

Selection of suitable respiratory protective equipment for work with asbestos. This guidance is primarily for employers and self-employed contractors throughout the construction and building maintenance industry; for people working with asbestos-containing insulation materials, including contractors licensed by HSE to do this sort of work. Safety representatives may also find it useful.

Why should I provide respiratory protective equipment?

Asbestos is the greatest single cause of work related deaths in Great Britain. Asbestos fibres accumulate in the lungs over time and a significant lifetime dose can lead to asbestos-related diseases. These are mainly cancers of the chest and lungs and they kill more people than any other single work-related cause. There is usually a long delay between exposure to asbestos and the onset of disease. This can vary between 15 and 60 years.

Smokers who are exposed to asbestos have an increased risk of developing an asbestos-related disease.

The vast majority of people now dying of asbestos-related diseases were exposed to asbestos during the 1950s and 1960s when its use was widespread. But, there is still a lot of material containing asbestos around, and if you are responsible for work on it or stripping it out, you must do all you can to prevent or reduce the exposure of those affected (e.g. workers and visitors) as much as possible.

We know the more asbestos fibres breathed in, the greater the risk to health, so it’s important that everyone who works with asbestos takes strict precautions to reduce exposure to them. This will include choosing the right respiratory protective equipment (RPE) for the job, making sure that it is used correctly and maintained in good condition.

When should I provide RPE?

The Control of Asbestos Regulations 2006 (CAR 2006) require you to do all that you reasonably can to prevent any exposure to asbestos fibres, or where prevention is not possible, to reduce exposure to the lowest possible level. Regulation 11 of CAR 2006 requires the provision of and wearing of RPE in addition to all other first line precautions. This is to minimise cumulative exposure over time, ie reduce as far below the control limit as possible. You must always provide suitable RPE if, despite the precautions taken, exposure to asbestos fibres is liable to exceed the ‘control limits’ laid down in the Regulations (see Table 1).

You should not use RPE as your only control measure. You must reduce asbestos fibre concentrations in air to a minimum before using RPE as well.

First level control measures to apply before resorting to RPE

For licensable work involving friable asbestos, you must, where it is reasonably practicable:

• Enclose the work area and keep it under negative pressure
• Use controlled wet removal methods (e.g. water injection, damping down the surface to be worked on)
• Use a wrap-and-cut method or glove bag technique where appropriate
• Use measures which control the fibres at source, for instance, by using type H vacuuming equipment directly attached to tools, but failing this, hand-held by a second employee right next to the source emitting the fibres (known as ‘shadow vacuuming’) You should remember that dry removal processes are unacceptable. Further guidance on control measures to apply is given in HSG 247 (2006) ‘Asbestos: The licensed contractors guide’ and in HSG 210 ‘Asbestos Essentials’ task sheets.

If you have reduced asbestos fibres in air as low as is reasonably practicable by using control methods at source, but exposures are still liable to be above the control limits, you must always provide suitable RPE for your employees.

The RPE provided must reduce the exposure as low as is reasonably practicable.

RPE and CE marking

The RPE you provide must be marked with a ‘CE’ symbol. This means it meets the minimum legal requirements, usually by conforming to a European Standard.

If you have HSE-approved equipment made before 1 July 1995, you can continue to use it, as long as it is suitable and is properly maintained to perform correctly.

How do I select suitable RPE for my employees?

Very carefully and in consultation with them. Discuss it with the safety representative if there is one.

RPE must be matched to:

• The exposure concentrations (expected or measured)
• The job
• The wearer
• Factors related to the working environment

Suitable RPE means:

• It provides adequate protection (e.g. reduces the wearer’s exposure to asbestos fibres as low as is reasonably practicable, and anyway to below the control limits) during the job in hand and in the specified working environment (e.g. confined spaces)
• It provides clean air and the flow rate during the whole wear period at least conforms to the minimum recommended by the manufacturer
• The facepiece fits the wearer correctly
• It is properly maintained
• The chosen equipment does not introduce additional hazards that may put the wearer’s health and safety at risk

When choosing RPE you need to think about:

• The expected concentrations of asbestos fibres in the air
• The protection factor values of different types of RPE
• The potential for oxygen deficiency and/or the presence of other hazardous substances (e.g. solvent vapours) within the work environment. You should be aware that particulate filters used for protection against asbestos fibres will not protect against oxygen deficiency, gases or vapours. Work in oxygen-deficient atmospheres must comply with the requirements of the Confined Spaces Regulations 1997
• The kind of work involved, e.g. more strenuous jobs may need a greater air supply
• The temperatures at which people will be working
• The facial characteristics of the wearers (e.g. beards, sideburns, stubble growth, glasses)
• The medical fitness of the people needing to wear the equipment
• The length of time the person will have to wear the equipment
• How comfortable it is and whether people will wear it correctly for the required length of time
• Whether the job involves extensive movements, restrictions and/or obstructions which need to be overcome while doing the job. In some circumstances the use of compressed airline breathing apparatus (CABA) may be impractical or can introduce secondary hazards such as tripping, entanglement, and the potential for spreading asbestos fibres outside the enclosure. The equipment may restrict mobility, making it difficult to work in restricted or heavily congested areas
• The need to communicate verbally during work
• The effects of other personal protective equipment and other accessories on RPE (e.g. unmatched goggles may affect the face seal provided by the face mask; jewellery may interfere with the performance of the RPE)

More details on these aspects can be found in HSE guidance note HSG53 Selection, use and maintenance of respiratory protective equipment.

Expected exposure concentrations

You can make an assessment of the expected concentration of asbestos fibres in air by considering:

• How easily the material crumbles
• How roughly you will need to treat it to do the job
• How much of it you will be working on
• How long you will be working on it
• How effective the control measures at source are in reducing the spread of dust and concentrations of asbestos fibres in air
• Available information (eg past exposure monitoring records for similar circumstances, information in tables 2 and 3)
• Past experience and knowledge which are relevant to the work in question
• An allowance for short-term unexpected high exposures

But, where there is doubt about the expected exposure concentration, you will have to confirm the concentration by air monitoring, using a method approved by the Health and Safety Executive (e.g. methodology described in HSE 264 ‘Asbestos: The survey guide’). If you are not sure that you can properly assess youremployees’ expected exposure to asbestos fibres, then get help from an occupational hygienist or a specialist laboratory.

To carry out asbestos-related sampling, air sampling and analysis, laboratories must be accredited by the UK Accreditation Service (UKAS). Where you have to confirm or reassess likely exposure concentration in air by personal exposure monitoring, until such information is available you will need to provide suitable RPE which can provide the best possible protection.

Tables 2, and 3 give you information on the sort of fibre concentrations you are likely to experience in a range of jobs. They are only a guide and are no substitute for carrying out a proper assessment of the likely exposure concentrations. The circumstances of each job can vary widely, so you must carry out a proper assessment.

Work with asbestos insulating board, coating and lagging (with very few specific exceptions) must be carried out by a licensed contractor. Table 4 gives typical fibre concentrations for well conducted stripping methods as well as unsatisfactory situations. Anything less than the well conducted methods is unacceptable and will lead to higher fibre concentrations.

During controlled wet stripping operations, parts of the lagging or coating might not be thoroughly wetted or a piece of lagging can come loose or drop off before you wet it. If this happens, you should take appropriate action before allowing the work to continue. If you ignore the situation, fibre concentrations can soar, in some cases, to above 1000 fibres/ml, which is far higher than commercially available RPE can protect against.

Remember, you have legal duties to reduce the exposure to asbestos fibres as low as possible.

Protection factors

Based on the outcome of your assessment, you will have to select suitable RPE. Remember, the concentration inside the facepiece of the RPE must be as low as possible and in any case must not exceed the relevant control limit.

Facepiece fit testing

People come in all sorts of shapes and sizes. Therefore, one particular size or type of RPE is unlikely to suit everyone. In addition, the performance of facepieces (e.g. filtering facepieces, half and full-face masks) depends on achieving a good contact between the wearer’s skin and the face seal of the mask. To make sure that the selected facepiece can provide adequate protection for the wearer, the initial selection should include quantitative fit testing.

A good fit would be one which indicates an inward leakage level at or below the value given in the appropriate EN Standard.

You can do this in a number of ways, including:

• Using a purpose-built test chamber
• Using an ambient particulate counting device

Test chamber

The test can be carried out in a chamber (laboratory-based or transportable) into which you can deliver, measure and maintain standard challenges of either sodium chloride aerosol or sulphur hexafluoride gas. Before testing, each wearer should be trained how to correctly fit his/her selected RPE, including the qualitative fit check recommended by the manufacturer.

Then ask the wearer to put on the RPE again, carry out the qualitative fit check and enter the test chamber. The test should measure leakage into the mask while the wearer walks on a treadmill, talks and moves their head in a manner appropriate to the type of work to be carried out. If the wearer/mask combination fails the fit testing, then the RPE should be checked for leaks, refitted and the test repeated. If the repeat test fails, provide the wearer with a suitable alternative and fit test. For filtering facepieces, the test is described in EN 149 and for half-mask RPE it is in EN 140.

Guidance document BSEN 529:2005 ‘Respiratory protective devices. Recommendations for selection, use, care and maintenance’ provides further guidance.

This test method is relatively expensive, time-consuming and requires a dedicated test facility, but has the advantages of accuracy and precision.

Ambient particulate counting device

The test using an ambient particulate counting device does not require a dedicated test chamber, sodium chloride aerosol or sulphur hexafluoride gas, so the test can be carried out at most workplaces. The exercise to be carried out is described in the section above. The device uses aerosol (particulates) in ambient air to perform the test, which means that the test results can be affected by variations in the type and concentration of ambient aerosol. For example, an assessment obtained in a smoky environment is likely to be different from that obtained in an office environment. Therefore, the device should be used with care by a trained and competent operator and in accordance with the manufacturer’s guidance.

Repeat quantitative face fit testing will be needed if changing to a different model of RPE or different-sized facepiece or if there have been significant changes to the facial characteristics of the wearer (e.g. loss or gain in weight).

Consulting employees

You will need to involve the wearers of RPE in the selection process and, where practicable, provide them with a choice of suitable equipment. This helps to ensure that it is suited to them and increases the chances that they will accept the RPE and wear it correctly.

Looking after RPE

Check that the RPE is clean and in good working order before you give it to the wearer, and before it goes back into storage. Badly maintained RPE will not provide adequate protection and the wearer’s health will be put at risk. Before use, you should, where appropriate, check on:

• The condition of the head harness, and the facepiece including seal and visor
• The condition of the inhalation and exhalation valves, where fitted. For example, dirty, curled-up or cracked valves will not perform properly and will severely compromise the protection provided the condition of any threaded connectors and seals
• The condition and type of filter(s), that they are ‘indate’ and fitted properly
• The airflow rate for power-assisted and powered respirators compared with the manufacturer’s specification
• Whether the RPE is complete and correctly assembled
• Additional tests in accordance with the manufacturer’s instructions

If you are providing breathing apparatus, check the flow rate and pressure of the air supply at the start and end of each shift. Also, ask wearers to check these at regular intervals during the shift. For all RPE, carry out additional tests or observations in accordance with the manufacturer’s instructions. The manufacturer of RPE should give you instructions on cleaning and maintenance. Make sure you follow them. After each use, RPE (except the disposable type) should be decontaminated, cleaned, disinfected and placed in storage specifically provided for that purpose.

All RPE should be thoroughly examined and tested, by trained personnel, at least once a month to make sure that it is working properly to its design specification. A record of inspection, examination, maintenance and defects remedied must be kept available for inspection by the enforcing authorities and others for five years.

Do not modify any form of RPE without the knowledge and consent of the manufacturer.

Further information about appropriate use of RPE when working with asbestos is available from a variety of publications and sources. Visit: www.hse.gov.uk

Published: 10th Nov 2010 in Health and Safety International