Asbestos safety

Asbestos safety:

What is asbestos:

Asbestos is a term used for the fibrous forms of several naturally-occurring minerals. All asbestos deposits originate from cystallisation of molten rock which, on cooling, produces the various types of fibrous forms. It is usually found as thin veins, up to a few inches thick, between layers of the parent
rock, which may be in non-fibrous or crystalline form.

Asbestos is the generic name for 6 different naturally-occurring fibrous minerals. A "fibre" is defined as a particle that is more than 5 micrometres (μm) in length and having a length to width ratio of at least 3:1.  Many Canadian regulations further add that a fiber of asbestos must also be less than 3 μm wide.

Types of asbetos:

Based on their physical and chemical properties, there are two major groups of asbestos: serpentine and amphibole. 

Serpentine: Serpentine fibres are long, flexible and curved. These fibres can be woven together. The main type of serpentine asbestos is chrysotile (white asbestos), which is the main type of asbestos used in manufacturing.

Amphiobole: Amphibole fibres are straight and stiff. These fibres are generally brittle and rod- or needle-shaped, which limits their commercial usefulness. There are 5 sub-types of amphiobole asbestos, including:

  • Crocidolite (blue asbestos)                                 
  • Amosite (brown asbestos)
  • Actinolite
  • Anthophyllite
  • Tremolite

Asbestos has been widely used in construction materials & for anumber of purposes including:

  • fireproofing
  • thermal insulation
  • electrical insulation
  • sound insulation
  • decorative plasters
  • roofing products
  • flooring products
  • heat resistant materials
  • gaskets
  • chemical resistance

What are the health effects of asbestos?

The human health effects from long-term unsafe asbestos exposure are well documented. Asbestos fibres are easily inhaled and carried into the lower regions of the lung where they can cause fibrotic lung disease (asbestosis) and changes in the lining of the chest cavity (pleura).  These diseases can lead to reduced respiratory function and death.  Long-term inhalation of asbestos fibres also increases the risk of lung cancer and mesothelioma.

Enlargement of the heart can also occur as an indirect effect from the increased resistance of blood flow through the lungs.

People are more likely to experience asbestos-related disorders if they:

  • are exposed to high concentrations of asbestos,
  • are exposed for longer periods of time, and/or
  • are exposed to asbestos more frequently.

What is the risk of lung cancer from working with asbestos?

The risk of getting lung cancer after asbestos exposure depends on a number of factors, the most important of which are:

  • the level (how much) and the duration (length) of exposure
  • the time since exposure occurred
  • the age at which exposure occurred
  • the tobacco-smoking history of the exposed person, and
  • the type and size of the asbestos fibres.

The average time from exposure to cancer development (latency period) is 20 to 30 years. Although lung cancer is generally associated with long-term exposures to asbestos, there are also studies which show that workers with 1 to 12 months of exposure had an increased risk in developing lung cancer a number of years later.

Lung cancer has also been reported in household contacts and family members of asbestos workers, presumably from exposure to asbestos carried home on work clothes.

Lung cancer usually does not cause symptoms in the early stages. When symptoms occur the cancer is often advanced. Symptoms of lung cancer include chronic cough, weight loss, shortness of breath, fever, and chest pain. These symptoms are also common with other lung disorders, therefore to confirm the diagnosis it is necessary to carry out laboratory tests including chest x-rays.

Chrysotile (white asbestos)

Amosite (brown asbestos)

Crocidolite (blue asbestos)

Summary of the different forms of Asbestos Containing Materials ACMs:

Sprayed asbestos:

Sprayed asbestos was applied as heatproofing,soundproofing and as protection against fire andcondensation on beams, connecting pieces and stays made of steel. A mixture of asbestos types was used. Sprayed asbestos is extremely friable and has a high potential for fibre release unless sealed.

Loose asbestos lagging:

Loose asbestos lagging was used as a filling material for heatproofing and soundproofing and as
protection against fire for pipe ducts, loft insulation and insulation between floors.

Thermal Insulation/ Lagging:

Thermal insulation was used to lag pipes, boilers and pressure vessels. It was either applied as a composite or in preformed pipe sections. The type and amount of asbestos used can vary greatly.

Asbestos cloths, tapes and cords:

Asbestos tapes and cords are found as heatproof and fireproof sealing material in fireproof doors and fireproof shutters, in smokeproof doors and gates, in kilns, boilers and high-temperature installations, in flanges on heating pipes and ventilation ducts. Cords and tapes were also used as filling materials in expansion joints. Cloths were used as jointing and packing, gaskets, thermal insulation and lagging including fire-resistant blankets, mattresses and protective curtains, gloves, aprons, overalls, etc.

Asbestos board/ panels:

Asbestos boards/panels were used as fireproof coverings for beams, connecting pieces and stays
made of steel or wood. They can contain chrysotile, amosite or crocidolite or a mixture of asbestos types. They were used widely in ducts and for fire-stopping, infill panels, partitions, ceiling tiles, roof underlays, wall lining, bath panels, external canopies and porch inings.

Asbestos is also found in insulating board cores and linings of composite products used for acoustic
attenuators, cladding infill panels, domestic boiler casings, partition and ceiling panels, oven linings and suspended floor systems. ‘Asbestolux’ and ‘Marinite’ are examples of the trade names.

Asbestos millboard, papers, cardboards, and gaskets:

These were used in particular for heat insulation and as fire protection in electrical appliances, to wrap electrical wires, as asbestos cardboard under floor coverings and to manufacture filter materials. Gaskets were used as sealing for acids, oils and under conditions of high temperature and pressure. These gaskets are known as CAF (Compressed Asbestos Fibre) gaskets. All types of asbestos have been used, but only Chrysotile since 1965.

Asbestos-containing bitumen/ tar:

Asbestos-containing bitumen and tar products were used in the manufacture of roofing felt, as a coating for flat roofs and guttering, as humidity insulating paint on the outer walls of cellars, and as joint sealant and casting compound. Asbestos was added to fireproofing coatings, anti-rust paint, adhesives and plaster-containing filler.

Asbestos-containing floor coverings:

Thermoplastic vinyl-asbestos tiles normally contain white asbestos (Chrysotile). They were mostly laid on bitumen adhesives, which can also contain asbestos. These tiles were laid on a large scale in public buildings, schools, etc., but also in private homes and offices. Asbestos-paper backed PVC flooring are foam PVC goods (cut from a roll). They are coated on the underside with a white or light grey asbestos cardboard.

Risk from as Asbestos containing textured coats and paints:

Textured coatings can be found on ceilings and walls. They normally contain Chrysotile asbestos. They were phased out from the late 1980s but are still widely in place, for example as ‘Artex’ on walls and ceilings in both commercial and domestic buildings.bestos and ACMs:

Products listed in order of potential for fibre release (High to Low):

  • Asbestos-contaminated dust (including dust left in place post asbestos removal)
  • Sprayed coatings, laggings and loose asbestos fillMillboard
  • Insulating Boards
  • Paper products & cardboard
  • Ropes, yarns and cloths (textiles)
  • Gaskets
  • Asbestos cement products
  • Textured decorative coatings and paints containing asbestos
  • Asbestos bitumen roofing felts & damp proof courses; semi rigid asbestos bitumen products and asbestos bitumen-coated metals
  • Unbacked vinyl & vinyl floor tiles
  • Mastics, sealants, putties and adhesives
  • Asbestos- reinforced PVC and plastics

Friable and non-friable ACMs

The Asbestos Survey (see section 8) should provide information to help determine whether an ACM is friable or non-friable. Generally, friability means that an ACM is less resistant to mild abrasion or damage and is more likely to release inhalable fibres, so the type of ACM, asbestos fibre type and condition are critical to determine friability.

Friable ACMs

  • Asbestos containing dust (ACD).
  • Sprayed coatings, laggings and loose asbestos fill.
  • Millboard.
  • Insulating Boards.
  • Ropes, yarns and cloths.
  • Paper products.
  • Vinyl flooring backed with asbestos paper.
  • Compressed Asbestos Fibre (CAF) gaskets.
  • Asbestos cement products in degraded state.

Non-friable ACMs:

  • Asbestos cement products in non-degraded state.
  • Asbestos bitumen roofing felts & damp proof courses, semi-rigid asbestos bitumen products and asbestos bitumen-coated metals.
  • Unbacked vinyl & vinyl floor tiles.
  • Textured decorative coatings and paints containing asbestos on plasterboard.
  • Mastics sealants, putties and adhesives.
  • Asbestos- reinforced PVC and plastics.

Sprayed asbestos

Loose asbestos

Thermal Insulation

Asbestos cloths

Asbestos board

Asbestos millboard

Aebestos bitumen

Asbestos-containing floor

Asbestos textured coats

Risk assessment of Asbestos containing materials (ACM s):

Purpose of risk assessment:

Risk Assessment is a key requirement of the 2005 Act and the Asbestos Regulations. Employers, including the self-employed, must identify and assess all ACMs present on-site before any maintenance, repair, demolition or refurbishment works commence, and they must carry out a written
risk assessment. Risk assessments must be prepared by a competent person who has training, knowledge and experience of the type of work and control measures available.

Examples would include:

  • An employer using his/her own employees, e.g. maintenance staff, to carry out work on his/her own premises,
  • An employer whose employees are contracted to work on a client’s premises, e.g. electrical contractor, plumbing contractor or asbestos removal contractor, and
  • A self-employed person working on a client site.

Risk assessment for ACMs should be transparent, comparable and verifiable if it is to meet the requirement of objectivity. Therefore, each ACM identified in a survey and described in an asbestos register will normally be assessed for the potential to release asbestos fibres using the materials assessment algorithm on four separate elements, as follows:

1) The type of asbestos material, e.g. lagging, board etc.,
2) Its condition, e.g. good condition; low, medium or high damage,
3) Its surface treatment, e.g. composite materials, unsealed lagging's, and
4) Type of asbestos identified, e.g. blue, brown, white etc.

The key steps for an asbestos risk assessment for asbestos removal are as follows:

  • Ensure that risk assessments are prepared by a competent person who has training, knowledge and experience of the type of work and control measures available,
  • Identify the type of asbestos and condition of the asbestos or asbestos-containing materials (asbestos survey information, i.e. materials assessments),
  • Determine the nature and degree of exposure which may occur during the course of the work, i.e. expected exposures and number of people affected. (Use published exposure levels for similar tasks, or information from previous monitoring exercises). It is important that the written risk assessment takes account of all of the features and activities of a particular site and includes a sufficient basis for the estimate of possible exposure. The written risk assessment should consider exposure of all who could be affected (e.g. operatives, occupants, members of the public, other contractors),
  • Set out and implement the steps to be taken to prevent exposure or reduce it to the lowest level reasonably practicable, e.g. priority assessments; procedures for the selection, provision, use and decontamination of personal protective equipment (PPE) including respiratory protective equipment (RPE); waste disposal; emergency procedures; provisions regarding equipment and training,
  • Consider the results of any air monitoring of exposure, e.g. previous results from a similar activity. If previous air monitoring data relating to a specific task is not available, or not available in the form of documented typical exposure concentrations’, then the written risk assessment must identify the need to conduct personal/background air monitoring to support the plan of work,
  • Record significant findings of that risk assessment and retain every risk assessment in a permanent form,
  • Consult with the employees concerned, or their representatives, or both, in respect of the risk assessment, and
  • Review risk assessment regularly, especially if there is reason to believe that 1) the assessment is incorrect, 2) the existing risk assessment is no longer valid, or 3) there is a change of a material nature in the work activity.

In summary, the risk assessment should cover the following points:

  • The type of work
  • The type and quantity of asbestos involved and the results of analysis
  • The details of expected exposures
  • Number of people involved
  • Whether the exposure limit value will be exceeded
  • Frequency and duration of exposure
  • Potential exposure of other persons
  • Air monitoring of similar previous works
  • Methods of asbestos removal and steps to be taken to reduce exposure to lowest level practicable e.g. dust suppression method
  • Measures to prevent the spread of asbestos to the surrounding environment
  • Provision, use and maintenance (including cleaning) of RPE & PPE
  • Procedures for personal decontamination
  • Procedures for dealing with emergencies
  • Procedures for removal/ disposal of waste
  • Thermal environment
  • Other hazards

Personal protective equipment:

Personal protective equipment (PPE), including respiratory protective equipment (RPE) is the last line of defence against exposure to asbestos fibres, which should be prevented or reduced to as low
as is reasonably practicable by engineering controls before RPE is employed. Once it is
established that exposure is liable to exceed the control limit of 0.1 f/cm3 despite the precautions taken, RPE must be provided and worn. This will normally include all notifiable asbestos work.

Respiratory protective equipment (RPE):

Various types of RPE are available and it is essential that the RPE selected matches the type of work to be done, taking into account the working environment, the wearer, other PPE in use and the exposure concentrations (expected or measured). In practice, asbestos workers are most likely to wear a limited range of PPE. A filtering facepiece (FF) particulate filter No.3 (P3) mask may be used for various tasks such as site pre-clean, site set-up, enclosure dismantling, waste handling outside the enclosure and decontamination unit (DCU) cleaning, whilst a full face power-assisted respirator with a P3 filter is required for entry into a live enclosure.

Employees must be given adequate instruction, information and training on the following:

  • How to fit and use the RPE correctly (including pre-use fit check each time it is worn),
  • The uses and limitations of all RPE worn in the work area,
  • How to recognise a reduction in air flow and what to do if it happens,
  • How to identify and replace worn or defective parts,
  • The manufacturer’s instructions on the use, storage and maintenance of the equipment,
  • How to clean contaminated RPE when leaving the work area, and
  • How to recognise medical signs and symptoms that may limit or prevent the effective use of RPE.

Other personal protective equipment Other PPE will be required, including:

  • Coveralls to prevent asbestos being spread from the workplace enclosure,
  • Wellington boots or other smooth, easily cleanable footwear (without laces),
  • Disposable underclothing, socks and gloves, and
  • Other PPE as required, if shown necessary by the risk assessment.

What are other health effects from asbestos?

Pleural Effects

Inhalation of asbestos fibres can also lead to four types of non-cancerous abnormalities in the lining of the chest cavity (pleura). These are:

  • localized deposits of collagen (pleural plaques);
  • fluid in the pleural space (pleural effusion);
  • diffuse thickening and fibrosis of the pleura; and
  • folded lung or rounded atelectasis (a condition which occurs when an area of pleural fibrosis rolls into the lung making a portion of the lung airless).

These pleural abnormalities are found in 10-60% of asbestos workers.  Pleural abnormalities are also common in family members of asbestos workers, presumably from exposure to asbestos carried home on work clothes.

In many cases, the development of pleural plaques is not seen for 20 to 30 years after exposure.  Pleural effusions (excess fluid between the two membranes that envelop the lungs) usually occur within 10 years after exposure.

Laryngeal Effects

Asbestos exposure has also been found to significantly increase the incidence of laryngitis in a small number of studies.

Immune System Effects

There have been several studies on the effects of asbestos exposure on the immune system. Most studies indicate that immune system function is reduced in workers with asbestos's. It has not been determined if the changes in immune function are the cause or the result of the asbestos's. In workers exposed to asbestos but who have not developed clinical signs of asbestos's, a depressed immune function is mild or no change has been noted.

Asbestos exposure may be a causal factor in the development of a rare condition known as retro peritoneal fibrosis. This condition is the development of a fibrous mass behind the membrane lining the abdominal cavity, which can result in kidney failure. There is a case control study and there are a number of case reports which indicate that asbestos exposure may be an important risk factor for retro peritoneal fibrosis.

What occupations could be exposed to asbestos?

According to the U.S. Agency for Toxic Substances and Disease Registry (ATSDR) and the U.S. Occupational Safety and Health Administration (OSHA), asbestos exposure is a concern for the following workplaces and processes:                                              

  • Mining of asbestos occurring from natural mineral deposits
  • Processing of asbestos minerals (millers)
  • Manufacture of asbestos-containing products
  • Construction industry - disturbing asbestos-containing materials during building renovations or demolitions
  • Mechanics - vehicle brake and clutch repairs
  • Marinas - renovating or demolishing ships constructed with asbestos-containing materials
  • Insulation workers and heating trades
  • Sheet metal workers, plumbers and pipe fitters
  • Workers responsible for disposing of asbestos waste, and waste workers
  • Cement workers
  • Custodial workers - contact with deteriorating asbestos-containing materials in buildings

What is the Threshold Limit Value (TLV) for Asbestos?

American Conference of Governmental Industrial Hygienists (ACGIH) recommended exposure limit for asbestos is:

TIME-WEIGHTED AVERAGE (TLV-TWA): 0.1 fibers per cubic centimeter (f/cc)* - Carcinogenicity Designation A1

The TLV basis for this rating is pneumoconiosis, lung cancer and mesothelioma.

TLV Definitions:

*Respirable fibers - Fibers longer than 5 microns and at least 3 times as long as their diameter as determined by the membrane filter method at 400-450 X magnification (4-mm objective) using phase contrast illumination.

CARCINOGENICITY DESIGNATION A1 - Confirmed Human Carcinogen: Substance is carcinogenic to humans based on convincing evidence from human studies. For a substance assigned a TLV®, exposure should be controlled to levels as low as reasonably achievable below the TLV®. Workers exposed to a substance without an assigned TLV should be properly equipped to eliminate virtually all exposure to it.

Are there different types of asbestos work?

In some jurisdictions (for example, Manitoba, Ontario and New Brunswick), working with asbestos is closely regulated.  Typically, the laws break the type of asbestos work into 3 classes:

  • Type I (low risk)
  • Type II (medium risk)
  • Type III (high risk)

A similar approach is used in the United States by the Occupational Safety and Health Administration (OSHA).  Note that the OSHA system uses the reverse order of numbering for the categories - for OSHA, Class I is the most potentially hazardous class of asbestos jobs, while Class IV refers to custodial activities where there is clean up of asbestos-containing waste and debris.  Please check the regulations for your jurisdiction for an exact list of which activities are in each class for your area.

Type 1 (low risk) involves:

  • Installing or removing ceiling tiles covering an area less than 7.5 square metres
  • Installing or removing other non-friable asbestos containing materials (ACM), and the tiles/material are not being broken, cut, drilled, abraded, ground, sanded or vibrated (e.g., dust is not being generated)
  • Breaking, cutting, drilling, abrading, grinding, sanding or vibrating non-friable ACM if the material is wetted to control the spread of dust or fibres, and the work is done only with non-powered hand-held tools. (e.g., dust is being generated, but easy to control)
  • Removing less than 1 m² of drywall in which joint-filling compounds contain asbestos.

Type 2 (medium risk) involves:

  • Removing all or part of a false ceiling to get access to a work area, if ACM is likely to be lying on the surface of the false ceiling.
  • The removal or disturbance of less than or equal to 1 m² of friable ACM during the repair, alteration, maintenance or demolition of all or part of machinery or equipment or a building, aircraft, locomotive, railway car, vehicle or ship.
  • Enclosing friable ACM.
  • Applying tape, sealant, etc. to pipe or boiler insulation that is ACM
  • Installing or removing ceiling tiles that are ACM if the tiles cover an area of greater than or equal to 7.5 m² and are installed or removed without being broken, cut, drilled, abraded, ground, sanded or vibrated.
  • Breaking, cutting, drilling, abrading, grinding, sanding or vibrating non-friable ACM if the material is not wetted to control the spread of dust or fibres, and the work is done only with non-powered hand-held tools.
  • Removing greater than or equal to 1 m² of drywall in which the joint filling compound has ACM.
  • Breaking, cutting, drilling, abrading, grinding, sanding or vibrating non-friable asbestos-containing material if the work is done with power tools attached to dust-collecting devices equipped with high efficiency particulate air (HEPA) filters.
  • Removing insulation that is ACM from a pipe, duct, etc. using a glove bag.
  • Cleaning or removing filters used in air handling equipment in a building that has sprayed fireproofing that is ACM.
  • An operation that is not mentioned above but may expose a worker to asbestos, and is not classified as a Type 1 or Type 3 operation.

Type 3 (high risk) involves:

  • The removal or disturbance of greater than 1 m² of friable ACM during the repair, alteration, maintenance or demolition of all/ part of a building, aircraft, ship, vehicle, etc.
  • The spray application of a sealant to friable ACM.
  • Cleaning or removing air handling equipment, including rigid ducting (excluding filters), in a building that has sprayed fireproofing that is ACM.
  • Repairing, altering or demolishing all or part of a kiln, metallurgical furnace or similar structure that is made in part of refractory materials that are ACMs.
  • Breaking, cutting, drilling, abrading, grinding, sanding or vibrating non-friable ACM, if the work is done with power tools not attached to dust-collecting devices equipped with HEPA filters.
  • Repairing, altering or demolishing all or part of any building in which asbestos is or was used in the manufacture of products.

Basic asbestos awareness training:

Basic asbestos safety awareness training must be provided to all employees who are or are likely to be exposed to asbestos-containing dust, e.g. in cases where the fabric of a building will be disturbed. As the aim of this training is to impart knowledge,this training will usually be theory based. The use of teaching aids such as photographs, diagrams and videos is strongly recommended.

The training should cover:

  • The properties of asbestos and its effects on health, including the synergistic effect of smoking,
  • The types of materials or products that may contain asbestos and where they are likely to occur,
  • The potential risks to health from exposure to dust arising from asbestos or asbestos containing materials,
  • The operations which could result in asbestos exposure,
  • How the condition of the material or products affects the ease of release of fibres,
  • What to do if materials suspected of containing asbestos are encountered, and
  • The relevant legislation and regulations.

A basic safety awareness course should be a minimum of one day’s duration with a maximum of twelve trainees per course. The training should cover the points mentioned in the asbestos awareness training section and should also cover:

  • The operations that could result in asbestos exposure,
  • The importance of effective control measures to prevent or minimise exposure to airborne asbestos and to prevent spread of asbestos contamination,
  • Safe working practices that minimise exposure, including control techniques,
  • Personal protective equipment, risk assessments and written instructions (plan of work),
  • The role of respiratory protective equipment, selection of the appropriate type of respiratory protective equipment, and its proper use,

What are good practices when working with asbestos?

  • Workers should not eat, drink, chew or smoke within any work area containing asbestos.
  • Drop sheets and barriers used in the work area should be wet-wiped or vacuumed with a HEPA-filtered vacuum.
  • Drop cloths should not be re-used.
  • Barriers and portable enclosures should not be reused unless they are rigid and can be thoroughly cleaned.
  • Compressed air must not be used to clean up and remove dust from any surface.
  • Clean the work area frequently and at regular intervals during the work and immediately on completion of the work.
  • Dust and waste should be cleaned up and removed using a vacuum equipped with a HEPA filter, or by damp mopping or wet sweeping, and placed in a container. The container must be:
    • dust tight and suitable for the type of waste,
    • impervious to asbestos,
    • labelled as containing asbestos waste with a warning that the dust from the contents should not be inhaled,
    • cleaned with a damp cloth or a vacuum equipped with a HEPA filter immediately before being removed from the work area, and
    • removed from the workplace frequently and at regular intervals.
  • Before leaving the work area, workers must decontaminate their protective clothing by using a vacuum equipped with a HEPA filter, or by damp wiping, before removing the protective clothing. If the protective clothing will not be reused, the clothing should be placed in a container as described above. Workers must wash their hands and face before leaving the work area. The employer must provide adequate wash facilities.
  • A double locker facility is often used to assist workers with cleaning up after working with asbestos, particularly after medium- to high-risk operations. A "double locker" requires two locker rooms with showers between. Using double locker rooms allows workers remove asbestos contaminated clothes in one locker room, then shower off asbestos contaminants, then use the second locker area to keep their street clothes.  Double locker rooms are required in certain jurisdictions.

Controlling the spread of dust beyond the work area is critically important so that people outside of the work area are not exposed to asbestos fibres. The specific controls to achieve this vary from using polyethylene sheeting barriers for low-risk operations, to setting up a separate ventilation system, maintained under a negative pressure for high-risk work areas.