Freshly renovated or newly built, and it smells: of paint, of adhesive, of "new". Behind this are usually VOC, volatile organic compounds, that off-gas from fresh building materials. Unlike the classic old-building pollutants, VOC are not a legacy of past decades; they arise precisely when renovating or building anew. Usually the smell is unpleasant but harmless, and it disappears with time. Sometimes not.
VOC comprise hundreds of substances, among them formaldehyde, toluene, xylene, styrene or limonene. They off-gas from paints, lacquers, adhesives, floor coverings, furniture and sealing compounds.
Where VOC come from
- Paints and lacquers: products labelled "low-solvent" too off-gas measurably in the first weeks.
- Floor coverings and adhesives: vinyl, laminate, parquet adhesive and sealers.
- Furniture: chipboard and MDF panels are the main source of formaldehyde.
- Insulation materials and assembly foams: for example PU foams.
- Silicones and sealants: fresh silicones release acetic acid or oximes.
Many VOC decrease noticeably in the first weeks. Other sources, above all formaldehyde from wood-based materials, off-gas for months to years.
When VOC are a problem
Not every smell is dangerous. But one should take seriously persistent complaints after a renovation: headaches, dizziness, irritated mucous membranes, nausea or difficulty concentrating.
The most critical individual substance is formaldehyde. The IARC of the WHO classifies it as carcinogenic to humans (Group 1). The indoor guide value is 0.1 mg/m³ (100 µg/m³) as a half-hour mean, derived by the Committee on Indoor Air Guide Values and in line with the recommendation of the WHO.
For the sum of all volatile compounds, the TVOC value serves as orientation, not as a health limit: up to about 0.3 mg/m³ the air is considered hygienically harmless, a value of 1 mg/m³ should not be exceeded permanently, and from about 3 mg/m³ there is a need for action. Important here: for individual substances such as formaldehyde, separate, health-based guide values apply that take precedence over the sum assessment. In Austria as in Germany there are no binding statutory limits for VOC in living spaces; the guide values of the Committee on Indoor Air Guide Values and of the WHO are used.
How to determine VOC
For persistent complaints, a room-air measurement provides clarity. An accredited laboratory breaks down the individual substances with their concentrations and forms the TVOC sum; formaldehyde is determined separately. From this profile the source can often be narrowed down, so that one can act in a targeted way instead of replacing everything.
What to do
- Ventilate intensively: in the first weeks after a renovation, burst ventilation several times a day for a few minutes is the most effective immediate measure. Before moving into a new build, it helps to heat and ventilate for a few weeks.
- Narrow down the source: if the complaints do not subside after weeks, a room-air measurement narrows down the source instead of replacing everything.
- Material choice: for future work, low-emission products off-gas considerably less, recognisable by labels such as EMICODE EC1, the Blue Angel or natureplus.
VOC are the counterpart to the legacies: here the new is the problem, not the old. Which pollutants are to be expected in which construction era is summarised in our overview by construction year; under old parquet, by contrast, PAH-containing adhesive often waits.
Sources
- German Environment Agency (UBA) and the Committee on Indoor Air Guide Values, TVOC assessment (target value 0.3 mg/m³, guide value 1 mg/m³, remediation range from 3 mg/m³) and precedence of substance-specific guide values
- Committee on Indoor Air Guide Values, formaldehyde guide value 0.1 mg/m³ as a half-hour mean (2016), in line with the WHO
- IARC/WHO, formaldehyde as a Group 1 carcinogen
- allum.de, „Formaldehyd: Grenzwerte und Richtwerte": allum.de
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