Asbestos content: what does asbestos-containing material mean?

Asbestos content describes how many asbestos fibres a material contains. For building materials, however, the decisive question is simpler: is asbestos found in the sample or not? If asbestos is detected, the material is asbestos-containing and must be removed as asbestos work, even if the amount of fibres is small. A low content does not turn the removal into ordinary demolition work. That is why the Semlab report does not state the percentage of asbestos, but whether asbestos was detected in the sample and which type of asbestos it is.

In this article we explain what asbestos-containing means in practice, why even a small amount of asbestos matters, why the content varies between materials, how asbestos content in a material differs from asbestos content in the air and what the laboratory report tells you.

What does asbestos-containing mean?

An asbestos-containing material is a material in whose sample asbestos fibres have been identified. In practice there are two cases:

• Asbestos detected: the material is treated as asbestos-containing. It must not be removed as ordinary demolition work – hire a specialist asbestos removal contractor that works in line with occupational safety rules.
• No asbestos detected: no asbestos was found in the sample, and the material can be handled as usual. The result applies to the material examined, not to other layers next to it or underneath it.

In everyday speech people often say a material "contains a bit of asbestos" or is "only slightly asbestos-containing". For removal work such expressions make no difference: asbestos-containing is asbestos-containing.

Why does even a low asbestos content matter?

What makes asbestos dangerous is not the weight of the material but the fibres that can get into the air you breathe. Asbestos fibres are so thin that even a small amount can correspond to a large number of respirable fibres. This is why even a material with a low content can release many fibres during removal.

• The working method matters a great deal. Sanding, chiselling, drilling and sawing grind the material into dust. Sanding filler or adhesive can produce dust with a high fibre count, 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.
• The fibres are invisible. Asbestos dust cannot be told apart from ordinary building dust with the naked eye, so you do not notice exposure while you are working.

If you are worried that you have been exposed, talk to your doctor or occupational health service.

Why does the asbestos content vary between materials?

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

The content can also vary within the same material. The composition of one and the same product could differ from batch to batch, and in compounds mixed on site the fibres may be unevenly distributed. In addition, older structures often have several thin layers on top of each other. If even one layer contains asbestos, the whole layer build-up to be removed is treated as asbestos-containing. Read more about layers in the article Asbestos in wall filler.

Content and tendency to release dust are two different things

How easily fibres are released from a material depends on how firmly the fibres are bound. In a hard asbestos cement sheet or vinyl tile the fibres are bound, whereas soft, crumbly insulation can release dust just from being touched. An intact, undisturbed material does not usually release fibres, but during removal fibres can be released from any asbestos-containing material.

In the Semlab report, each sample is given a dust release class from 0 to 5 (the report's 0–5 risk rating), which describes how easily fibres can be released from the material. A negative sample has class 0. This information helps when planning the removal, but it does not change the fact that the material contains asbestos.

Asbestos content in materials and in the air

The term asbestos content is used in two different senses, and it is worth keeping them apart.

• The asbestos content of a material is determined with a material sample, i.e. a small piece of filler, adhesive, board or insulation. It shows whether the material to be removed contains asbestos and which type of asbestos it is.
• The asbestos content of the air is determined with 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 how clean a room is after asbestos removal.

Before a renovation, a material sample is almost always what is needed. An air sample does not show whether the filler on the wall or the adhesive on the floor contains asbestos.

What does the laboratory report show?

Semlab analyses material samples with a JEOL SEM-EDS electron microscope according to the ISO 22262-1 standard. The microscope shows the shape of the fibre, and the elemental analysis shows its composition. For each sample, the report contains:

• the sample details: site, material and sampling location
• the result: positive, negative or uncertain
• the type of asbestos detected, if asbestos is found: chrysotile, amosite, crocidolite, anthophyllite, tremolite or actinolite
• the dust release class 0–5

The report also contains the date the samples were received and the report date, a description of the method, a general note on interpretation, the analyst's signature and photos of the samples as an appendix. The report does not state a percentage of asbestos or a content class. An uncertain result should be confirmed with a new sample.

The result is emailed in English on the same day the sample arrives at the laboratory. A negative result covers all six types of asbestos. The result always applies to the sample you sent, which is why it is important that the sample is representative. How to read the result is explained in the article Understanding your 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 intend to remove.

1. Take the sample where the work will be done. If the surface has been repaired at different times, take a separate sample from each area that looks different.
2. Wear disposable gloves and at least a class FFP3 respirator.
3. Moisten the sampling spot with a spray bottle so that as little dust as possible is produced.
4. Remove a piece of about 2–5 centimetres so that all layers down to the substrate are included. A sample that is too small, or one taken only from the top layer, can miss the asbestos-containing layer.
5. Put the piece in a resealable bag, seal it and pack it in a second bag. Write the sampling location and material on the bag.
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 an asbestos analysis cost?

The analysis costs €49.99 incl. VAT per sample. You pay by card when you order, and postage is not included in the price. You can order the analysis online and post the sample to the laboratory as a letter or small parcel with your national postal service.