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Indoor air concentrations of formaldehyde, furfural, benzaldehyde, and 11 aliphatic aldehydes (C2-C11) were measured in residences of 639 participants in the German Environmental Survey for Children and Adolescents 2014-2017 (GerES V). Sampling was conducted using passive samplers over periods of approximately seven days for each participant. The most abundant compounds were formaldehyde and hexanal with median concentrations of 24.9 µg m-³ and 10.9 µg m-³, respectively. Formaldehyde concentrations exceeded the Guide Value I recommended by the German Committee on Indoor Guide Values (Ausschuss für Innenraumrichtwerte - AIR) (0.10 mg m-³) for 0.3% of the participating residences. The sum of aliphatic n-aldehydes between C4 (butanal) and C11 (undecanal) exceeded their Guide Value (0.10 mg m-³) for 2.0% of the residences. The geometric mean concentrations of most aldehydes were lower than in the earlier GerES IV (2003-2006) study. Formaldehyde and hexanal concentrations, however, were comparable in both studies and showed no significant difference. Indoor aldehyde concentrations did not exhibit significant correlations with factors collected in questionnaires, such as the age of the participants, their socio-economic status, the location of the residence (former East/West Germany), migration background, tobacco exposure, and the type of furniture used. The validity of the passive sampler measurements was verified against active sampling techniques in a test chamber experiment.

The chemical background of olfactory perception has been subject of intensive research, but no available model can fully explain the sense of smell. There are also inconsistent results on the role of the isotopology of molecules. In experiments with human subjects it was found that the isotope effect is weak with acetone and D6‐acetone. In contrast, clear differences were obvious in the perception of octanoic acid and D15‐octanoic acid. Furthermore, a trained sniffer dog was initially able to distinguish between these isotopologues of octanoic acid. In chromatographic measurements, the respective deuterated molecule showed weaker interaction with a non‐polar liquid phase. Quantum chemical calculations give evidence that deuterated octanoic acid binds more strongly to a model receptor than non‐deuterated. In contrast, the binding of the non‐deuterated molecule is stronger with acetone. The isotope effect is calculated in the framework of statistical mechanics. It results from a complicated interplay between various thermostatistical contributions to the non‐covalent free binding energies and it turns out to be very molecule‐specific. The vibrational terms including non‐classical zero‐point energies play about the same role as rotational/translational contributions and are larger than bond‐length effects for the differential isotope perception of odor for which general rules cannot be derived.

The release of volatile organic compounds from building products may influence the perceived air quality in the indoor environment. Consequently, building products need to be assessed for the acceptability of emitted odors. The standard ISO 16000-28 describes the evaluation of perceived odor in test chambers with trained panelists, being calibrated with diluted acetone. For the direct odor assessment, ISO 16000-28 requires an air flow of 0.6 - 1.0 l/s at the chamber outlet. To meet these conditions under normal air exchange rates, the minimum chamber volume is about 3 m³. If smaller chambers are used, air must be collected into containers for an indirect assessment. Procedures for the handling of the containers are provided in the ISO standard. Nevertheless, the indirect assessment method has a number of pitfalls and drawbacks. Experiments with sampling-container materials such as NalophanUPTM and Tedlar® and different sampling techniques (continuous vs. discontinuous) have shown that the composition of sampled air might be influenced by the container material due to sink effects and leakage. The recoveries of the target VOCs in the sampling container decreased in dependence of decreasing vapor pressure and increasing octanol/air distribution coefficient.1-butanol and 1-hexanol have high recovery rates in NalophanUPTM containers. These substances therefore appeared to be suitable for investigations into the synergistic odor effect. It could be shown that mixtures of 1-butanol and 1-hexanol have no clear additive effect in the sensory evaluation. This calls into question the practical relevance of an odor guide-value concept based on individual substance evaluations.

Three-dimensional (3D) printers using the fused filament fabrication technique are in widespread use, and they are known to emit ultrafine particles (UFPs) and volatile organic compounds (VOCs). This fact raises concerns due to their impact on indoor air quality and human health. Several emission control measures have been previously proposed but without being confirmed in the near real-life situation. In this study, the effectiveness of the control measures in reducing the UFPs and VOCs was tested in a standardized 30 m3 environmental test chamber. We found that a filter cover and an air purifier were effective in removing 74-93% of UFPs, with the filter cover providing the best UFP filtration. Control at the source location seems to be more efficient than trying to remove particles following their emission. However, the control measures showed varying abilities to remove major VOCs of styrene and ethylbenzene. Moreover, new VOCs were emitted from the use of control devices. After the newly opened filters had been conditioned and the control devices had been operated for 4-5 days, the VOC emissions decreased. The study shows the necessity of further studies of VOC control measures, which should preferably have efficient and consistent removal ability, as well as minimal emissions.

With regard to the application of semi-volatile organic compounds (SVOCs) in products for indoor use, a distinct trend towards substitutions can currently be observed. Among the possible phthalate alternatives, in particular the adipic acid esters have gained in market importance. The chemical-physical and thermodynamic properties of the phthalates and adipates allow the conclusion to be drawn that they are distributed between different compartments (gas phase, particle phase, dust, material surfaces) of the indoor space. There are, however, hardly any data in existence which were collected in a real environment over six months and longer. Diisobutyl adipate (DiBA), di-n-butyl adipate (DnBA), dipentyl phthalate (DPP), butyl benzyl phthalate (BBzP) and di-2-ethylhexyl adipate (DEHA) were selected as model substances. By means of spiked latex paint and spiked house dust, these SVOCs were introduced into two identically equipped test rooms. One room was cleaned regularly, whilst the reference room was not entered for a 133 day experimental period. The concentrations of the five target substances were determined in the air and in material samples (carpet, vacuum-cleaner bags, filters). During the operation of an air purifier, the air concentration of the target substances in a room could be reduced by more than 50%. In the reference room, a correlation between the logarithmic air concentration and the reciprocal room temperature was found. The results show with great clarity the complexity of the conditions in an indoor room. Models can therefore depict the exposure as a statistical average but not, however, describe the individual case.

The emission of ultrafine particles (UFP) and gaseous pollutants from 3D printing has been increasingly gaining attention in recent years due to potential health risks. The physical and chemical properties of the emitted particulate matter, however, remain unclear. In this study, we characterized these particles with a focus on their chemical composition and volatility, and measured the gaseous pollutants from desktop 3D printing in a standardized environmental test chamber. Eight types of filaments were tested, including ABS (acrylonitrile butadiene styrene), ASA (acrylonitrile styrene acrylate), HIPS (high impact polystyrene), PETG (polyethylene terephthalate glycol), and PCABS (polycarbonate & ABS). Particle size distribution (PSD), particle number concentration (PNC), particle chemical composition and particle volatility were measured. In addition, volatile and very volatile organic compounds (VOCs and VVOCs) emitted during 3D printing were analyzed. The specific emission rates (SERs) for particles in the size range of 5.6 to 560 nm ranged from 2.0 × 109 (GLASS, a PETG-based filament) to 1.7 × 1011 (ASA) #/min. The particle SERs for ABS were (4.7 ± 1.1) × 1010 #/min. The SERs for total volatile organic compounds (TVOC) varied from 0.2 μg/min (GLASS) to 40.5 μg/min (ULTRAT, an ABS-based filament). Particles started to evaporate extensively from 150 °C. At 300 °C, only 25% of the particle number remained with the size distribution mode peaked at 11 nm. The particles collected on the quartz filter were mainly composed of semi-volatile organic compounds (SVOCs) associated with the plasticizers, flame-retardants, antioxidants of the thermoplastics, and cyclosiloxanes which may be used as lubricants in the 3D printer. Keywords: 3D printing, Emission, Ultrafine particles, VOCs, SVOCs, Environmental test chamber

Emissionsprüfkammern werden zur Beurteilung von Emissionen flüchtiger organischer Verbindungen (VOC) aus Materialien eingesetzt. Üblicherweise werden derartige Untersuchungen unter dynamischen Bedingungen durchgeführt, da sie die Verhältnisse im Innenraum möglichst gut simulieren sollen. Im Gegensatz zu der sonst üblichen statischen Methode wurden in der vorliegenden Arbeit die Eigenschaften von vier unterschiedlichen Emissionsprüfkammern unter dynamischen Bedingungen ermittelt und verglichen. Zwei 1m³-Kammern mit Prüfräumen aus Glas bzw. Edelstahl, eine 23.5l-Glaskammer und eine Emissionsmeßzelle aus Edelstahl standen zur Verfügung. Zunächst wurden die Luftgeschwindigkeiten und Strömungsverläufe in den vier Kammer untersucht. Die Strömungsgeschwindigkeiten in der Emissionsmeßzelle konnten mit einem speziellen Messaufbau bestimmt werden. Es wurde gezeigt, daß die Strömungsprofile in einer Kammer schon durch kleine Probenkörper empfindlich gestört werden können. Weiterhin wurden Sink-Effekte der Emissionsprüfkammern bestimmt. Dafür mußte ein Verfahren zur kontinuierlichen Aufgabe und Analyse kleiner Stoffmengen entwickelt werden. Die dynamischen Eigenschaften der leeren Kammern wurden dann durch Aufnahme von Konzentrationsanstiegs- und -abklingkurven eines Gemischs verschiedener halogenierter Aromaten studiert. Es konnte gezeigt werden, daß das Kammermaterial selbst keinen meßbaren Einfluß auf den kammereigenen Sinkeffekt hat. Weitere Experimente zur Temperatur- und Feuchte- und Substanzabhängigkeit des Sinkeffekts wurden durchgeführt., Emission test chambers are used to determine the emission of volatile organic compounds (VOC) from different materials. For a good simulation of the indoor environment, test are carried out under dynamic conditions. While the evaluation of test chambers is normally performed under static conditions, this thesis presents the evaluation of four different chamber types under dynamic conditions. Two 1m³-chambers made of glass and stainless steel, a 23.5l-glass chamber and an emission cell were tested. Air velocities and the flow field of all chambers were determined. A special anemometer had to be designed to measure air velocities inside the emission cell. It was shown that even small samples may have a serious impact on the chamber flow field. The sink effects in the test chambers were studied by means of a mixture of halogenated aromatic hydrocarbons. Analytic methods had to be set up to measure the concentration rise and decay curves, which were used to calculate the sink effect of the empty chambers. Additional experiments were carried out to determine the influence of temperature, humidity and the substance's physical properties on the sink effect.