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

An old wooden floor can give a room plenty of character. However, especially with older parquet and wooden floors, renovation work or a suspected contamination raises the question of which materials were used in the past. The wood itself is not necessarily the problem: old parquet adhesives, wood preservatives, varnishes and coatings may contain pollutants that are no longer used today or whose use is now restricted.

Possible pollutants include polycyclic aromatic hydrocarbons (PAHs) as well as former wood preservatives containing PCP (pentachlorophenol) or lindane. 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?

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

• PAHs: Polycyclic aromatic hydrocarbons may occur particularly in old tar-based parquet adhesives.
• PCP: Pentachlorophenol was formerly used in wood preservatives, among other applications, due to its fungicidal properties.
• Lindane: This insecticide was also used in the past as an ingredient in wood preservatives, sometimes together with PCP.
• PCBs: Polychlorinated biphenyls may occur in older building materials, for example in certain varnishes or coatings.
• Formaldehyde and VOCs: Volatile substances may be released from adhesives, paints, coatings and wood-based materials.

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.

PAHs in old parquet adhesives

Tar-based adhesives are a particular concern in older parquet floors. Tar can contain high concentrations of PAHs. Old parquet adhesives can therefore be a potential source of these pollutants.

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

PCP and lindane in former wood preservatives

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

Various substances that are considered problematic today were formerly used for wood preservation, including PCP, lindane and DDT. Such products could also have been applied to wooden building components indoors.

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.

Can pollutants from wooden floors affect indoor air?

Certain pollutants from treated wood, adhesives, varnishes or coatings may also be relevant to the indoor environment. Whether and to what extent substances are released depends, among other factors, on the material used, the pollutant present and the condition of the floor.

The appropriate type of investigation therefore depends on the specific question and the suspected source. Depending on the situation, material or dust samples can be analysed.

How can you recognise a potentially contaminated wooden floor?

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

• ✓ older parquet or wooden flooring of unknown construction
• ✓ old dark or black adhesive layers beneath the parquet
• ✓ indications that the wood was previously treated with wood preservatives
• ✓ large areas of older wood indoors
• ✓ planned renovation, sanding or dismantling 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, laboratory testing can provide useful information. The appropriate sample depends on the suspected source and the specific situation.

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

With our Indoor Air Analysis for Wood Preservatives, dust or material samples can be tested for around 50 semi-volatile organic compounds (SVOCs). These include PCP, lindane, PCBs, DDT and various PAHs.

What should you do if pollutants are detected?

A positive result does not automatically mean that the entire wooden floor has 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.

Before remediation or dismantling work, the necessary protective and remediation measures should be clarified. For significant contamination or extensive work, it is advisable to consult a specialist in building pollutants.