Pollutants in Wooden Floors: What Can Be Found in Old Parquet?

An old wooden floor can add a lot of character to a room. However, particularly with older parquet and wooden floors, renovation work or concerns about pollutants can raise questions about the materials that were used in the past. The wood itself is not necessarily the problem: old parquet adhesives, wood preservatives, varnishes and coatings can contain pollutants that are no longer used today or whose use is now restricted.

Possible pollutants include polycyclic aromatic hydrocarbons (PAK) as well as substances such as PCP or lindane from older wood preservatives. However, the age or appearance of a floor alone cannot reliably determine whether contamination is actually present.

Which pollutants can occur in old wooden floors?

Different groups of substances may be relevant depending on the age, construction and treatment of the floor. Some were deliberately used as wood preservatives in the past, while others may be found in adhesives or coatings.

• PAK: Polycyclic aromatic hydrocarbons can occur particularly in old tar-based parquet adhesives.
• PCP: Pentachlorophenol was formerly used in wood preservatives due to its fungicidal properties.
• Lindane: This insecticide was also used as a component of wood preservatives, sometimes together with PCP.
• PCB: Polychlorinated biphenyls can occur in certain older building materials.
• Formaldehyde and VOCs: Volatile substances can be released from adhesives, paints, coatings and wood-based materials, among other sources.

According to the Swiss Federal Office of Public Health (FOPH), solid wood itself generally causes no or only low emissions. When assessing an older wooden floor, it is therefore important to consider the entire floor structure and any previous treatments.

PAK in old parquet adhesives

Tar-based adhesives are particularly relevant when assessing older parquet floors. Tar can contain high concentrations of PAK. Suva provides information on PAK in old building materials and identifies old parquet adhesives as one possible source.

A dark or black adhesive underneath old parquet may raise suspicion, but its colour alone is not sufficient for an assessment. Tar and bitumen can look similar while differing significantly in their PAK content.

PCP and lindane in older wood preservatives

The adhesive beneath parquet is not the only potential source of pollutants. In the past, wood was sometimes treated with chemical wood preservatives. Well-known active substances include PCP and lindane.

Information from the Canton of Zurich on building pollutant diagnostics shows that various substances now considered problematic were formerly used to protect wood. These include PCP, lindane and DDT. Such products could also have been used on wooden components inside buildings.

Certain pollutants can remain detectable in treated wood for a long time. An investigation may therefore still be useful in older buildings if there is a specific suspicion that wood preservatives were previously used.

How can you recognise a potentially contaminated wooden floor?

Pollutant contamination generally cannot be reliably identified by appearance or smell alone. However, certain indications may justify a closer investigation:

• ✓ older parquet or wooden flooring with an unknown construction
• ✓ old dark or black adhesive layers underneath the parquet
• ✓ indications that the wood was previously treated with wood preservatives
• ✓ large older wooden surfaces indoors
• ✓ planned renovation, sanding or removal work
• ✓ unknown materials underneath the floor covering

Have a wooden floor tested for pollutants

If it is unclear whether an older wooden floor or the materials used contain pollutants, a laboratory analysis can provide useful information. The appropriate type of sample depends on the suspected source and the specific situation.

1. Identify the possible source: Is the concern related to the wood itself, an old parquet adhesive, a coating or a previous wood preservative treatment?
2. Select a suitable sample: Depending on the question, dust or material samples can be analysed.
3. Take the sample correctly: Careful sampling helps prevent contamination and supports a meaningful analysis.
4. Laboratory analysis: The sample is analysed specifically for the relevant groups of pollutants.
5. Assess the result: The analysis result can then be used to determine whether further investigations or measures are required.

Our Wood Preservatives Analysis examines dust or material samples for around 50 semi-volatile organic compounds (SVOCs). These include PCP, lindane, PCB, DDT and various PAK.

What should you do if pollutants are detected?

A positive result does not automatically mean that the entire wooden floor needs to be removed. Important factors include the type and concentration of the pollutant, the condition and location of the contaminated material, and the planned use or renovation work.

Before renovation or removal work begins, the necessary protective and remediation measures should be clarified. In the case of significant contamination or extensive work, it is advisable to consult a specialist in building pollutants.