Atmospheric Chemistry Program Seminar: Tunga Salthammer, Fraunhofer WKI
Assessment of indoor air quality using substance-specific guide values and TVOC
Prof. Tunga Salthammer
Department of Material Analysis and Indoor Chemistry, Fraunhofer WKI
"The primary goal of indoor hygiene studies is to create a pleasant and healthy environment for people. This requires a sufficient supply of fresh air and the setting of climatic parameters that lead to thermal comfort. However, the concentration of air pollutants must also be kept as low as possible. A complete measurement program to study indoor air quality can be both time-consuming and expensive. For this reason, parameters that can be measured easily and quickly are often used for an initial assessment of the situation. One of these parameters is TVOC (Total Volatile Organic Compounds).
The current situation makes it necessary to subject VVOC, VOC, SVOC and TVOC measurements to a critical analysis due to their widespread use in questions of indoor air quality and to the evaluation of emissions of organic compounds from building and consumer products.
A detailed description of the measurement methods is followed by a critical evaluation of the various TVOC values, their possible applications and guide values for individual compounds. The aim is to provide a deeper understanding of TVOC in order to use this parameter correctly and to be able to better assess published results. The analytical definition of VOCs also suggests total values TVVOC and TSVOC for very volatile and semi volatile organic compounds. However, due to the physical properties of the potential target chemicals, this is associated with a number of drawbacks.
Early work on TVOC was trend-setting and still influences current indoor guide values, even if many VOCs are no longer representative from today's perspective. The spectrum of indoor VOCs has shifted significantly: away from classic solvents and more towards reactive compounds and indoor chemistry. However, within the framework of surveys TVOC can make contributions to identifying statistical trends and reference values can be extracted from the data collected in this way. The online measured TVOC values are at best suitable for screening IAQ. TVOC does not take into account the toxicological properties of the individual substances for inhalation exposure. This would not even be possible, since different substances usually have different toxicological endpoints that cannot simply be summed up for a reliable risk assessment. Therefore, measurements of individual substances are usually evaluated using substance-specific guide values.
Consequently, TVOC cannot be used in connection with health-related and odor-related issues. Nevertheless, such references are repeatedly made, either intentionally or unintentionally. This happens in an analytical but also in an interpretative sense. Authorities, practitioners and architects use TVOC as an acceptance criterion for buildings, but without specifying the methodology. Overall, there is a great deal of uncertainty about TVOC. This applies in particular to the question of whether and why a TVOC value can be helpful and which statements cannot be made on the basis of the TVOC."
Reference: Salthammer, T. (2022). TVOC revisited. Environment International, 167, 107440, DOI link: https://doi.org/10.1016/j.envint.2022.107440 (published under CC BY-NC-ND 4.0).