Article from volume 3 Issue 3, Spring 2003 of Countryside Building
The Journal of the Rural Design and Building Association
Working with asbestos cement products
By Tony Hutchinson, Director
General of the Asbestos Information Centre Ltd
Working with asbestos containing
materials (ACMs) is controlled by the ‘Control of Asbestos at Work Regulations
2002’, which came into force on the 21st November 2002, except for
regulation 4 concerning the management of asbestos in non-domestic premises and
regulation 20 about the accreditation of people who analyse materials to
identify asbestos, which will come in to force on 21st May 2004 and
21st November 2004 respectively.
In my last article in the previous
issue of Countryside Building I set out the bare bones of the regulations. In
this article I will provide advice on working with asbestos cement products
where a licence is not normally required. I will not cover working with
low-density ACMs where a license is usually required. There are very few
situations in working farm buildings where low density ACMs would have been
used.
In the next issue of Countryside
Building due for publication in June I will cover the management of ACMs in
non-domestic buildings, this is Regulation 4 of the regulations and will come into
force on 21st May 2004.
The following article is only a
brief guide; it is not a complete guide to Health and Safety responsibilities
when working with asbestos containing products nor is it a complete guide to
health and safety responsibilities when on a construction site. Anyone working
with asbestos cement products should read and understand the Approved Code of
Practice L27 ‘Work with asbestos which does not normally require a licence
(Fourth edition) and the guidance ‘Working with Asbestos Cement’ available from
HSE Books
Asbestos
CementAsbestos CementAsbestos Cement
Asbestos
Cement is primarily a cement-based product where about 10% to 15% w/w asbestos
fibres are added to reinforce the cement. Asbestos cement is weatherproof in
that although it will absorb moisture, the water does not pass through the
product. It was used for corrugated
sheets, slates, flat sheets for animal pens, claddings, moulded fittings,
soffits and undercloak, water cisterns, rainwater gutters, down pipes, pressure
pipes, underground drainage and sewer pipes, sills, copings, chalkboards,
fascias, infill panels, etc.
It
is sometimes difficult to tell the difference between an asbestos cement product
and a low-density insulation board, but there are a few rules that can be
followed. The ACM will be asbestos cement if:
·
the product has been used as a roofing
or cladding product, open to the weather. Manufacture of all low density
products was stopped in the late 70’s and since they were not weather
resistant, if they had been fixed outside they would have broken down long
before now.
·
the product is moulded as low-density
products were not moulded, except as half rounds for pipe lagging.
·
the product is in sheet form and has
been used as animal pens or in wet areas. Low density products were not robust
enough to be used as animal housing nor could they withstand wet conditions
without breaking down.
When
cementitious products like asbestos cement were manufactured, they had a
cement-rich surface. The asbestos fibres
were encapsulated within. Thus, occupants of buildings with asbestos cement
sheet or slate roofs are unlikely to be at any greater risk than people outside
in the fresh air. The small quantities of fibres released during natural
weathering are unlikely to be dangerous but significant and possibly dangerous
amounts of fibre can be released if the products are subject to any abrasive
cleaning or working. It is therefore
important to use the correct techniques and working practices when handling
asbestos cement ACMs.
Non-asbestos alternatives to asbestos cement began to be introduced to the UK market in 1984, but asbestos cement products continued to be supplied into the UK market until 1999. So any product that looks like asbestos cement that was supplied prior to 1984 will contain asbestos, any product supplied after 1984 until 1999 could be an ACM. Unless one can find an identification mark on the product it is not possible for the layman to look at a sheet and tell whether it contains asbestos or not and in many cases even an expert can not tell without finding the mark or having a sample analysed. The manufacturers’ mark on profiled sheets is indented into the overlap of the side lap roll, it will normally, in code form, give the name of the manufacturer, the date of manufacture, the shift and possible the machine it was made on. If it contains asbestos it will contain the letters AC if it is non-asbestos it will contain the letters NT. With slates the mark was ink jetted on to the back of approximately one in twenty products, with the same letters denoting whether they contain asbestos not.
Finding these marks can
be a problem, with slates a quantity will need to be removed before the mark is
found and so unless you have good reason to believe that they are non-asbestos they should be treated
as an asbestos cement ACM. For roofs fixed after 1984, when the slates could be
asbestos cement or non-asbestos, looking at the original specification may help
but a number of specifications were changed by the roofing contractor because
asbestos cement slates were cheaper than their non-asbestos alternatives, and
the client and designer were not necessarily notified of the change. It may
therefore be necessary if one has to work on these products to either treat
them as ACMs or arrange for a sample to be removed and analysed by a competent
laboratory.
With
Profiled sheets identification is not a lot easier, although the sheets should
have carried the indent on the overlap roll this did not always happen or the
imprint is too vague to be read. There is also the problem that unless the roof
is relatively resent it will be dirty and covered in moss and lichens, which
will once again make the marks harder to read. It should of course be
remembered when accessing the roof to check for the mark that both asbestos
cement and unreinforced fibre cement sheets are very fragile and so protection
must be provided to the operative to ensure that he cannot fall through the
product, a far more immediate and serious risk than the risk of catching an asbestos related disease.
In
the mid 1990s some profiled sheet manufacturers started to inkjet the underside
of their sheets with the production mark. On a single skin construction this
should be seen from ground level and again if there is the letters AC in the
mark then it is an ACM if the letters NT are in the mark then the product does
not contain asbestos.
For
other moulded products the position of the mark will vary, with some having no
mark, where there is a mark the same lettering applies.
Very
few flat sheet products will have any marks.
The
action level is calculated by multiplying the air born exposure in
fibres/millilitre (f/ml) by the time in hours for which it lasts, to give
exposure in fibre-hours/ml. Cumulative exposure is calculated by adding
together all the individual exposures over the 12-week period.
So
as a simple example an operative working on asbestos cement products containing
chrysotile only, for four 4 hour shifts a week for 12 weeks, when in each 4hr
shift their average f/ml is 0.2, will have an action level of:
The
above example of an f/ml of 0.2 is probably very high if the work is on roofing
and cladding in the open air.
The
vast majority of builders and contractors working on farms will not be working
on ACMs full time, in fact it is probable that only a small percentage of their
time will be spent working with these materials and so the Action level is not
something that is likely to be exceeded but it does need to be watched. If a
large job, with much of the work inside, was taken on which was going to take a
considerable amount of time then it is possible that the Action level will be
breached. For example if we take the above example but the operative works four
8 hour days per week in the same conditions, then he will just exceed the
Chrysotile action level and of course well exceed the other fibres Action
Level.
General Responsibilities where neither the Action Level nor the Control Limits are going to be exceeded
The following
responsibilities on an employer to protect his employees also apply to the
general public and others as far as is reasonably practicable.
Identification of the type of asbestos
There is now
a responsibility to either sample the product being worked on to ascertain the
type of asbestos fibre involved or to treat the asbestos as if it is either
Crocidolite (blue) or Amosite (brown).
Following
discussion with the HSE they have confirmed that the majority of asbestos
cement products were made using chrysotile only and since the fibres are locked
into the matrix of the product, if the product is handled correctly the amount
of fibre release will be very low and so there is probably no good reason to
ascertain the type of asbestos used.
Risk assessment and method statements
Before work
starts the employer must ensure that a competent person carries out a suitable
risk assessment and that a method statement is provided on how the work is to
be actioned to comply with these regulations. The risk assessment and method
statement shall:
·
Determine
the nature and degree of exposure
·
Reduce
the exposure to asbestos to the minimum possible. Consider ways of doing the
work without disturbing the ACM, only if that is not possible should the ACM be
disturbed.
·
State
whether the employees might be exposed to asbestos fibre levels in excess of
the Control Limit or the Action Level, if they are take the steps listed below
under ‘Action Levels and Control Limits’ must be followed.
·
It
is not necessary to provide a risk assessment for every individual job. Where
an employer carries out work that involves very similar jobs on a number of
sites such as roofing, only one assessment for that work may be needed. When
one is considering using a risk assessment written before, it is important that
the job is inspected to ensure that the conditions of the ACM and the site are
the same as the previous jobs. It is possible in very extreme cases for
asbestos cement products to be attacked by acids or alkalis to such an extent
that the cement matrix is eaten away to leave the raw asbestos. This can happen
in very poorly ventilated animal housing. The fibre counts in the building are
likely to be so high and the product so friable that it should be treated as a
low-density product and handled by a Licensed Asbestos Contractor.
·
The
risk assessment should be reviewed if there is any reason to believe that the
original is no longer valid, such as a change in the condition of the ACM or
the work required.
·
The
method statement should be written for the job, it is not acceptable to provide
a generic method statement. It must be kept on site during the work.
·
The
method statement must list the place of work, the methods to be used to keep
the release of asbestos to the minimum possible and the characteristics of the
equipment to be used.
·
The
employer must ensure that as far as reasonably practicable the work is carried
out in accordance with the method statement.
·
Where
situations occur that are not covered by the method statement such as the
discovery of other ACMs or a change in the ACMs condition, work must stop until
another method statement to cover the new situation is written.
Actions to be taken if an Action Level is likely to be exceeded
Where
the risk assessment shows that the Action Level may be exceeded the following
actions have to be taken:
There
are a lot more details of the medical requirements set out in the ACOP 1.
Where
the risk assessment shows that the Control Limit may be exceeded, the following
steps must be taken:
These
requirements when either the Action Level or the Control Limit may be exceeded
are very onerous for a normal farmer, agricultural builder or contractor and so
if the risk assessment shows that an Action Level or Control Limit may be
exceeded, serious consideration should be give as to whether your company is
competent to do the work. It is better to turn the work away and recommend that
a firm with more expertise in handling ACMs is used than you doing the work and
getting it wrong.
Methods to reduce the release of fibres to the minimum
Before
starting work check whether the work is necessary, is it possible to carry out
the work without disturbing the ACM? A typical example is re-roofing, a risk
assessment will often show that over roofing will provide the least risk. If a
building is being demolished the removal
of the ACMs is required prior to demolition as far it is possible to do so.
If the
following methods are used to work on asbestos cement products that are not in
a very friable condition the fibre counts are likely to be very low and
certainly well below the Control Limits.
·
Keep the material wet when working on
it.
·
Avoid using power tools and breaking
ACMs but carefully remove or cut fixings so that the product can be removed in
one piece. Carefully carry to the ground and either double wrap in polythene or
place in a covered skip.
·
Where it is necessary to cut or drill
asbestos cement sheets, ensure the material is wet and if possible scribe and
break, if this is not possible use hand tools, preferably in the open air.
·
Keep the site clean and tidy at all
times and clean up after work by dampening any dust and carefully placing in a
polythene bag for disposal as asbestos waste.
·
Unless the risk assessment shows that
RPE is required, the operatives should preferably wear a disposable mask that
is CE marked to EN 149 with FFP2 particulate filters and disposable overalls,
which should be disposed of at the end of the shift as asbestos waste.
·
When working at heights follow the
advice in HSG 33 Health and safety in roof work (1998)4. Old
asbestos cement sheets are very fragile.
·
Any plant or equipment contaminated
with asbestos must be thoroughly decontaminated before being removed from site.
·
When the work is complete if it has
been inside a building and is not of a minor nature then Clearance air sampling
and a certificate of reoccupation will be required. Guidance on this can be
found in ACOP Work with asbestos insulation, asbestos coating and asbestos
insulation board5
Cleaning
Asbestos Cement Roofs.
This
should only be carried out if it cannot be avoided; moss and lichens although
some may think them unsightly are not normally detrimental. Asbestos cement is
very fragile and so the recommendations in HSG 33 Health and safety in roof
work (1998) must be followed.
Do
not clean by dry scrapping or by pressure washing, both can produce dangerous
quantities of free asbestos fibres. Either:
·
Use remote cleaning. This technique
involves skilled operatives using units with enclosed rotary cleaning heads and
high-pressure water jets, the filtering of the water run off and the disposal
of the filter waste as asbestos waste. It should only be carried out by skilled
specialist contractors.
·
Cleaning with surface biocides. The
biocides are applied with low-pressure sprays or as washes. The roof is then
left for the moss and lichen to die, when it can be gently brushed from the
roof with soft brushes. It is important that the roof is kept wet during the
brushing and the waste is carefully collected placed in plastic bags and
disposed of as asbestos waste.
An employer must ensure that any area where asbestos is being worked on is cordoned of and the necessary danger signs erected. He must ensure that workers and others not involved in the work cannot enter the area. The signage will depend on the amount of fibre that the risk assessment shows is likely to be created, i.e. if the risk assessment shows that a Control Limit is likely to be exceeded the signs must state that it is a Respiratory Zone.
No
eating, drinking or smoking should be allowed in the designated asbestos areas
and employers must provide suitable areas outside of the designated areas for
their employees to eat and drink in.
Air
monitoring of an employees’ exposure to asbestos will be required if the risk
assessment shows that an action level is going to be exceeded. If this is the
case:
·
Records must be kept that gives, the
type of work being carried out, the type of sample, the location, the date and
time, sample duration and flow rate, the length of time the individual was
exposed. The measured fibre concentrations, the fibre type and the names of the
sampler and their organisation.
·
The monitoring must be carried out by a
competent person who is accredited to comply with the ISO 17025, and then
analysed by an approved method.
·
Where the action level has been
exceeded the records of the air monitoring must be kept for at least 40 years,
if they are not exceeded they should be kept for at least 5 years.
Employers
must ensure that every employee who is exposed or likely to be exposed to
asbestos are provided with adequate washing and changing facilities. Where the
employer is required to provide protective clothing, he must also provide
adequate storage for the protective clothing and the employees personal
clothing. More information is available in ‘Provision, use and maintenance
of hygiene facilities for work with asbestos insulation and coatings 6
Information, Instruction and training
Employers
must ensure that their employees have received adequate training, understand
the risk assessment and know and understand the method statement. This training
should include:
·
All
workers who are involved in maintenance should receive asbestos awareness
training in case they come across ACMs of which you are unaware.
·
The
health risks of asbestos.
·
The
types, uses and likely occurrence of asbestos in buildings and plant.
·
The
details of how an emergency should be handled.
·
How
to avoid the risks from asbestos.
·
The
correct use of protective equipment
·
Refresher
training should be provided on a regular bases and at least once a year for
those regularly involved in working with ACMs.
·
There
is a responsibility on the employer to ensure that adequate information is
provided to non-employees who are on the premises and could be affected by the
work.
·
The
procedures for providing information, instructions and training should be
clearly defined and set out in a written document.
·
Records
should be kept of every individuals training.
Asbestos waste
Asbestos
waste is any waste, which contains more than 0.1% w/w asbestos. It is subject
to the waste management controls set out in the Special Waste Regulations 1996.
This states that the waste must be consigned as soon as possible by a licensed
haulier to a dump licensed to take asbestos.
At
the moment there is the exception that if the site being worked on is on
registered agricultural land, then it is lawful for a farmer to dispose of
asbestos waste originating from agriculture by burial on the originating farm.
The Environment agency is unhappy that farmers are able to avoid the special
waste regulations in this way and so it is expected that in the near future the
regulations will be changed to ensure that agricultural waste is treated in the
same way as waste from any other source. From July 2005
farmers will not be allowed to bury asbestos containing waste, it will have to
be taken to a dump licensed to take asbestos
Your
local authority should have a list of licensed hauliers and waste dumps in you
area.
The above is only a brief
guide, it is not a complete guide to Health and Safety responsibilities when
dealing with asbestos containing products, for more information obtain and
understand Approved Code of Practice and
Guidance L 27 ‘Work with asbestos which does not normally require a licence’ –
HSE Books
A M Hutchinson
Director General
Asbestos Information
Centre Ltd
ATSS House
Station Road East
Stowmarket
Suffolk
IP14 1RQ
Phone 01449 676900
e-mail director@aic.org.uk
web site www.aic.org.uk
Further
reading
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Asbestos Information Centre Ltd |
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