Asbestos content: what does "contains asbestos" mean?

Asbestos content describes how much asbestos fibre a material contains. For a building material, though, the deciding question is simpler: is asbestos detected in the sample or not? If asbestos is detected, the material is asbestos-containing and its removal is carried out as asbestos work, even if there is only a small amount of fibre. A low content does not turn the removal into ordinary demolition work. That is why Onelab's report does not state a percentage of asbestos; it tells you whether asbestos was detected in the sample and which type it is.

This article explains what "asbestos-containing" means in practice, why even a small amount of asbestos matters, why content varies from one material to another, how asbestos content in a material differs from asbestos concentration in the air, and what the laboratory report tells you.

What does "asbestos-containing" mean?

An asbestos-containing material is one in which asbestos fibres have been identified in the sample. In practice the classification has two outcomes:

• Asbestos detected: the material is treated as asbestos-containing. It must not be removed as ordinary demolition work; the removal is carried out by a company authorised for asbestos removal work.
• No asbestos detected: no asbestos was detected in the sample, and that material can be handled in the normal way. The result applies to the material tested, not to other layers next to it or underneath.

People often say that a material "contains a little asbestos" or is "only slightly asbestos-containing". For removal work, those expressions make no difference: asbestos-containing is asbestos-containing.

Why does even a low asbestos content matter?

The danger of asbestos does not come from the weight of the material but from the fibres that get into the air you breathe. Asbestos fibres are so thin that even a small quantity of fibre can mean a large number of respirable fibres. That is why a material with a low content can release plenty of fibres when it is broken up.

• The way you work matters a lot. Sanding, chiselling, drilling and sawing grind the material into dust. Sanding a filler or adhesive can produce a great deal of fibre-laden dust, even if asbestos makes up only a small part of the mass.
• All types of asbestos are carcinogenic. The aim is therefore to avoid exposure altogether, not just to reduce it.
• You cannot see the fibres. Asbestos dust cannot be told apart from ordinary building dust by eye, so you do not notice exposure while working.

If you are worried about possible exposure, talk to a doctor or your occupational health service. More on asbestos exposure in the article asbestos exposure: symptoms and health risks.

Why does asbestos content vary between materials?

Asbestos was added to products for different purposes and in different amounts. In some old products, such as sprayed insulation coatings, asbestos could make up most of the material, and asbestos cement also contained a considerable share. In others, such as adhesives, fillers and vinyl tiles, asbestos was typically only a small part of the mix, added to improve strength or workability. Both are asbestos-containing.

Content can also vary within the same material. The composition of a product could differ from one production batch to the next, and in compounds mixed on site the fibre may be unevenly distributed. On top of that, old structures often have several thin layers on top of each other. If even one layer contains asbestos, the whole layer build-up being removed is treated as asbestos-containing. Layers are covered in the article asbestos in walls.

Content and dustiness are different things

How easily fibres come loose from a material depends on how firmly they are bound. In a hard asbestos cement board or vinyl tile the fibres are locked in, whereas soft, crumbly insulation can shed dust at a touch. An intact, undisturbed material generally does not release fibres, but any asbestos-containing material can release fibres when it is removed.

In Onelab's report, samples are given a dustiness class 0–5 (the report's risk classification 0–5), which describes how easily fibres can come loose from the material. A negative sample has class 0. The class helps when planning the removal, but a low class does not change the fact that the material is asbestos-containing.

Asbestos in a material versus asbestos in the air

Asbestos content is talked about in two different senses, and it is worth keeping them apart.

• The asbestos content of a material is determined from a material sample: a small piece of filler, adhesive, board or insulation. It tells you whether the material you are about to remove contains asbestos and which type.
• The asbestos concentration in the air is determined from an air sample, in which room air is drawn through a filter and the fibres caught on it are counted. It is used, for example, to assess exposure or to check that a space is clean after asbestos removal. Read more on the asbestos air sample page.

Before a renovation you almost always need a material sample. An air sample does not tell you whether the filler on a wall or the adhesive under a floor contains asbestos.

What does the laboratory report tell you?

Onelab analyses material samples with a JEOL SEM-EDS electron microscope in accordance with ISO 22262-1. The microscope shows the shape of each fibre, and the elemental analysis shows its composition. For each sample the report gives:

• the sample details: site, material and location
• the result: positive, negative or uncertain
• the asbestos type detected, if any: chrysotile, amosite, crocidolite, anthophyllite, tremolite or actinolite
• a dustiness class 0–5

The report also gives the dates the samples were received and reported, a description of the method, a general guide to interpreting the results, the analyst's signature and an appendix of sample photos. It does not give a percentage of asbestos or a concentration class. An uncertain result is best confirmed with a new sample.

The result is sent by email, typically on the day the sample arrives. A negative result covers all six types of asbestos. The result always applies to the sample delivered to the laboratory, so a representative sample is important. Reading the result is covered in the article interpreting the asbestos result, and what to do after a positive result in the article positive asbestos result.

How do you get a representative sample?

Because asbestos can be unevenly distributed and hidden in a thin layer, the sample must represent exactly the spot and the layer build-up you plan to remove.

1. Choose the sampling spot where the work will take place. If the surface has been repaired at different times, take a separate sample from each different area.
2. Wear disposable gloves and a respirator of at least class FFP3.
3. Mist the sampling spot with a spray bottle to keep dust to a minimum.
4. Remove a piece of about 2–5 centimetres so that every layer comes with it, down to the substrate. A sample that is too small, or taken from the surface layer only, can miss the asbestos-containing layer.
5. Put the piece in a zip-lock bag, seal it and pack it inside a second bag. Mark the bag with the sample location and material.
6. Cover the sampling spot with tape and wipe the area with a damp cloth.

More detailed instructions are in the article how to take an asbestos sample.

How much does the analysis cost?

The analysis costs €39.90 + VAT per sample, and the price is the same for 1–100 samples. Orders of more than 100 samples can be priced separately. Postage is not included. You can order the analysis online and send the sample to the laboratory by post.