Recommendations on Polycyclic Aromatic Hydrocarbons (PAH) in Apartments with Parquet Flooring
Results of a follow-up symposium on 28/4/1998 at the Federal Environmental Agency
Following on from the first symposium on 25th March, scientists and representatives of federal, state and local authorities met once again to discuss pollution from polycylic aromatic hydrocarbons (PAH) in apartments with parquet flooring. The aim was to clarify still unresolved issues and produce concrete recommendations for action to reduce pollution from PAH. The experts were aware of the growing concern among those affected about the carcinogenic properties of PAH, especially the most important representative of this substance group, benzo(a)pyrene (BaP). While there have been various regulations for dealing with this problem laid down by individual authorities, the symposium was intended to develop a nationally applicable procedural approach. The experts came to the following recommendations for immediate and medium-term action:
1. Where optical examination shows that the glue in a parquet floor is dark" - indicating the presence of tar and bitumen - the content of the most important PAH, benzo(a)pyrene (BaP), in the glue is to be examined.
2. If the parquet glue has a BaP content below 10 milligramme per kilogramme (mg/kg), no further action is required.
3. If the BaP content of the parquet glue is above 10 mg/kg, a graded response is recommended:
- With a BaP content of 10 to 3,000 mg/kg in the parquet glue, the house dust is to be examined:
- If more than 10 mg BaP per kilogramme house dust are found, short-term measures to minimise the pollution should be taken.
- Where house dust contains less than 10 mg/kg BaP, it should be decided on a case by case basis whether medium-term action is to be taken.
With a BaP content of over 3000 mg/kg in the parquet glue and over 10 mg/kg BaP in the house dust, short-term measures to minimise the pollution should be taken.
With a BaP content of over 3000 mg/kg in the parquet glue and under 10 mg/kg BaP in the house dust, BaP concentrations are to be measured simultaneously in the indoor and outdoor atmosphere. Recent measurements have shown that, contrary to what has been assumed up to now, a high BaP content in the glue can give rise to increased BaP concentrations in indoor air. The outdoor air must be examined because BaP there reaches the indoor air through atmospheric exchange. If the indoor atmospheric concentration of BaP is more than double that found outdoors, or at least 3 nanogramme per cubic metre (ng/m3, = millionth of a gramme per cubic metre) higher, short-term measures to minimise the pollution should be taken.
4. The experts were agreed that the state of the parquet floor itself is significant. However, they were not able to provide assessment standards, as this form of judgement should be made by building experts.
5. The decision over the form and extent of medium-term measures could be assisted by the results of studying urine samples for PAH catabolism products (human biomonitoring), although the specific results are difficult to interpret in practice.
The following points are important with respect to measures to be taken to reduce pollution from parquet floors: for technical and aesthetic reasons, replacement of old parquet flooring can often be necessary. A suitable method should be chosen so that - alongside the creation of a perfectly usable floor - the release of PAH into the interior by tar-based glue should at least be effectively and lastingly reduced. The choice of action depends significantly on the degree of damage to the parquet floor. Work should only be carried out by professional contractors. In detail, this means:
- If the parquet is seriously damaged, i.e. if a large number of tiles are loose or there are very wide gaps, complete removal of the surface is generally to be considered. The remaining tar-based glue should be removed at the same time where possible, although the not inconsiderable dust produced during sanding or planing should be taken into consideration. This can make extensive occupational safety measures necessary.
- If the glue cannot be removed, it should be covered with appropriate airtight materials, over which a new, unglued covering (such as carpeting, laminate or imitation parquet) can be laid. If the old parquet is still fixed and usable, the simplest case is to cover it with a new layer (such as carpeting, laminate or imitation parquet), although the resulting raising of the floor level should be noted.
- If the old parquet floor can be neither removed nor covered, it can, under certain circumstances, be sealed with products sold in specialist shops. Gaps in parquet floors can be closedup with standard pastes or cement or sealed with elastic acrylate-based grouting, sold in a range of wood colours by specialist shops. Especially in the case of oak parquet floors, gaps smaller than three millimeters can be filled with the aforementioned pastes and, if the floor is then sealed with three to four coats of water-soluble specialist products based on acrylates or polyurethane, a good finish can be achieved. However, it can be assumed that, because of the limited durability of these solutions, the flooring will need to be renovated regularly.