For a thoughtfully designed indoor environment
Preliminary remarks: Highly volatile substances can be detected in almost all indoor environments. Since elevated concentrations can cause health problems—such as mucous membrane irritation, headaches, and susceptibility to infections—measuring these compounds indoors can be an important step in identifying the source of the issue.
Volatile organic compounds (VOCs) are primarily released indoors immediately after application—such as during varnishing, painting, or the use of adhesives—or, for instance, after the installation of new furniture. Provided the affected rooms are adequately ventilated, normal concentration levels generally return within a few weeks or, at most, a few months; however, application issues with VOC-containing products—and the resulting potential for continuous VOC emissions—can pose a long-term problem. Furthermore, some VOCs can be generated over time through decomposition reactions. Examples include the breakdown of indoor-relevant plasticisers such as dibutyl phthalate and diethylhexyl phthalate, resulting in the formation of n-butanol and 2-ethyl-1-hexanol, as well as the release of C4–C9 aldehydes from linoleum flooring.
Indoor air sampling for VOCs is carried out using the active enrichment method in accordance with DIN EN ISO 16000 Part 5, employing activated carbon, Tenax TA®, or XAD2. In principle, passive long-term sampling is also an option. Analysis is performed following solvent desorption (for enrichment on activated carbon and XAD2) or thermal desorption (for enrichment on Tenax TA®) using gas chromatography (GC) coupled with flame ionisation (FID) and mass spectrometer (MS) detectors.
There are few binding guidelines or limit values for volatile organic compounds. Research to date indicates that, as the total concentration of VOCs rises, adverse health effects generally increase or emerge in the first place.
Therefore, technical literature recommends aiming for a long-term average total VOC concentration in indoor air of 200 to 300 µg/m³—representing a “precautionary hygiene range”—or staying below this level whenever possible. At VOC concentrations below 200 µg/m³, no adverse effects on human health are generally documented, even with prolonged exposure, provided that the guideline values (Guideline Value I or II) for individual components are not exceeded. According to Seifert (1999), the total VOC concentration in rooms intended for occupancy should not permanently exceed 1,000 to 3,000 µg/m³.
For the following individual VOCs, the following toxicologically substantiated guideline values established by the German Environment Agency currently exist:
A guideline value of 30 µg/m³ for the total concentration of xylenes has been established by the State Committee for Immission Control. For perchloroethylene in the vicinity of dry-cleaning facilities, a legally binding limit value of 100 µg/m³ is set under the Federal Immission Control Act (BImSchG).
Guideline Value I (RW I) represents the concentration of a substance in indoor air at which—based on current knowledge and considering the substance in isolation—no adverse health effects are to be expected, even with lifelong exposure. Exceeding this value implies a level of exposure that is hygienically undesirable and goes beyond what is considered normal. As a precautionary measure, action is also required when concentrations fall within the range between RW I and RW II. RW I is derived from RW II by applying an additional factor (typically 10). This factor is based on convention.
RW I can serve as a target value for remediation. Ideally, concentrations should remain below this value rather than reaching it.
Guideline Value II (RW II) is an effect-based, substantiated value derived from current toxicological and epidemiological knowledge regarding a substance’s effect threshold, incorporating uncertainty factors. It represents a concentration level that, if reached or exceeded, necessitates immediate action, as such a concentration poses a potential health risk—particularly to sensitive individuals—during prolonged stays in the affected rooms. Depending on the substance’s mode of action, Guideline Value II may be defined as either a short-term value (RW II K) or a long-term value (RW II L).
The need for action is to be understood as a requirement for immediate assessment—for example, regarding decisions on remediation measures to reduce exposure.
Indoor air concentrations of compounds for which no guideline values have been established can only be assessed by comparing them with reference measurements. To this end, the former Federal Health Office (BGA) conducted measurements in 479 representative indoor spaces during the 1990s. The distribution of the values measured in that study is presented in Appendix 1 (BGA distribution statistics) alongside the current measurement. For instance, the value in column “10” indicates that 10% of all indoor spaces showed concentrations below this level (the 10th percentile). Columns for the 50th, 90th, 95th, and 98th percentiles are provided in the same way. This allows the measurement obtained from the sample in question to be compared with the reference data and classified into different categories. A value below the 10th percentile can be classified as notably low, while a value above the 90th percentile can be classified as elevated. These empirical data do not allow for conclusions regarding toxicity; however, they do make it possible to determine whether a concentration is typical or significantly elevated.
Using updated laboratory data, the AGOEF e.V. (Working Group of Ecological Research Institutes) developed reference values for volatile organic compounds in indoor environments.
Note: Certification confirms that a product met the requirements of the applicable testing programme at the time of testing. It does not provide a comprehensive assessment of a product’s suitability for health or of the health effects of an entire indoor environment.
Testing building products against published criteria since 1982.
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