PAH Diagnosis in Switzerland

What are PAHs and where are they found in buildings?

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds derived from the incomplete combustion or thermal distillation of organic matter. They are naturally present in coal tar and petroleum pitch, two substances massively used in building waterproofing and dampproofing products from the early twentieth century until the 1980s.

In old buildings, PAHs are found in several types of materials:

• Bituminous waterproofing membranes and coatings: flat roofs and roof terraces constructed before the 1980s were often waterproofed with coal pitch-based materials loaded with PAHs. These membranes are still present beneath more recent repair layers.
• Parquet adhesives and underlays: bitumen or tar-based parquet adhesives, widely used in the 1950s–1970s for laying wooden floors, often contain high concentrations of PAHs. They are found as a black layer beneath old parquet floors.
• Bituminous tile adhesives: certain adhesives used for tiling in service rooms, cellars or industrial premises were bitumen-based.
• Foundation waterproofing renders: the buried parts of old buildings (foundations, cellar walls) were often protected with bituminous renders that may contain PAHs.
• Car park and technical room coatings: certain floor paints and industrial coatings applied in the 1960s–1980s contained tar-based resins.
• Road surfaces integrated into structures: the traffic surfaces of car parks and access ramps made with tarred asphalt may contain PAHs.

Health risks of PAHs

PAHs comprise several hundred compounds, some of which are recognised as particularly hazardous to human health.

• Carcinogenicity: benzo[a]pyrene, one of the PAHs most frequently present in old building products, is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC) — meaning that evidence of its carcinogenicity in humans is established. Other PAHs are classified as probable carcinogens. The main cancer associated with PAH exposure is bronchopulmonary cancer.
• Exposure pathways: during works on materials containing PAHs (cutting, sanding, thermal stripping, heating during removal of waterproofing membranes), vapours and dust loaded with PAHs are released. Inhalation is the primary exposure pathway for workers. Prolonged skin contact with PAH-containing materials or dust also presents a risk.
• Chronic exposure: repeated exposure to low doses of PAHs over long periods constitutes a documented occupational risk for construction workers.

When is a PAH diagnosis necessary?

Verification of PAH presence is required before any construction site likely to disturb old bituminous or tar-containing materials. The most frequent situations are:

• Renovation or replacement of a flat roof: if the existing roof contains old waterproofing layers that will be cut or removed, PAH verification is indispensable.
• Removal or sanding of old parquet: a parquet laid with black bituminous adhesive must be verified before any sanding or stripping.
• Works on floors with bituminous underlay: remediation works on industrial floors or cellars may involve PAH-containing materials.
• Partial or total demolition: the pre-demolition inventory also covers bituminous materials, and the quantification of PAH waste is necessary to plan its disposal.
• Foundation waterproofing works: underpinning works or cellar remediation affecting foundation renders may expose tar-containing materials.

The Swiss regulatory framework

• The Waste Ordinance (OLED) and related ordinances define the PAH content thresholds that determine waste classification and applicable disposal channels. Materials exceeding the thresholds are classified as special waste or polluted excavation material according to their nature.
• The Ordinance on Construction Work (OTConst) requires verification of hazardous substances before any construction site. PAHs fall into the category of carcinogenic substances whose presence must be assessed before any intervention likely to expose workers.
• The occupational exposure limit values set by Suva govern the permissible concentrations of PAHs in workplace air.

How a PAH diagnosis works

• Inspection and identification of suspect materials: the diagnostician inspects the zones concerned by the works and identifies bituminous or tar-containing materials likely to contain PAHs. The presence of black, sticky materials or materials with a tar odour is a visual indicator, but not sufficient to establish a diagnosis — only analysis can confirm and quantify.
• Sampling: cores or material scrapings are taken according to standardised protocols. For multi-layer waterproofing membranes, the sample covers all existing layers.
• Chromatographic analysis: samples are analysed by gas chromatography coupled with mass spectrometry (GC-MS) in a SAS-accredited laboratory. This method allows individual PAHs present in the sample to be identified and quantified, particularly the 16 priority PAHs defined by the EPA/OENO.
• Report and recommendations: the report specifies the location of positive materials, the concentrations measured for key PAHs, the risk assessment for the planned works, and recommendations on worker protection measures and waste disposal conditions.

Management of waste containing PAHs

Waste from works on materials containing PAHs is subject to disposal obligations according to its content:

• Materials with low concentrations: may be disposed of in inert material landfills or construction waste treatment facilities according to cantonal thresholds.
• Materials with high concentrations: classified as special waste, they must be disposed of in specially authorised facilities, with the issuance of tracking documents in accordance with the OMoD.

Prior knowledge of PAH concentrations in the materials to be removed is indispensable for correctly planning disposal and avoiding cost overruns linked to incorrect waste classification.

PAH diagnosis in Geneva and the canton of Vaud

PAHs are frequently encountered in buildings in the cantons of Geneva and Vaud, primarily in flat roof waterproofing coatings (widespread in the property stock from the 1960s–1980s) and in old parquet adhesives. Our experts operate throughout both cantons within the framework of a comprehensive building pollutant diagnosis.

Combined approach with other pollutants

In buildings from the 1950–1985 period, PAHs are frequently present alongside other pollutants — asbestos, PCBs and lead. A multi-pollutant diagnostic mission allows all hazardous substances to be identified in a single intervention, with a single synthesis report. This approach is particularly recommended for heavy renovation or demolition projects where several types of materials will be affected.

Visit our asbestos diagnosis Western Switzerland page for an overview of the multi-pollutant approach, or request a personalised quote for your project.