Online & Oslo, Norway
21-23 June 2021
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Session 17: Odour and emissions
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Achieving a healthy indoor air by using an emissions barrier
1Lund University, Sweden; 2cTrap Ltd, Sweden; 3Sulin Oy, Finland
Spread of chemical and biological emissions from construction materials of a building into the indoor air may result in symptoms such as asthma, skin and eye irritation, fatigue etc. Here we report the use of an emissions barrier developed at Lund University Sweden for stopping and binding such emissions without affecting the building structure (Markowicz P, Larsson L, Atmospheric Environment 106 (2015) 376-381). We describe three premises with complaints on the indoor air quality where installing the barrier resulted in decrease or disappearance of measured as well as perceived emissions.
1. A townhouse where the tenants suffered from symptoms (itchiness) when staying at home was studied. A PVC flooring had been glued onto a concrete slab which had become moist through diffusion of water from the ground. The air concentration of 2-ethylhexanol, a compound formed from hydrolysis of glue and/or phthalates of PVC floorings, was 63 µg/m3 (directional measurement). The barrier was attached onto the existing flooring, and the symptoms disappeared. 3 months after barrier had been installed the air concentration was 1.5 µg/m3, a value which persisted in a follow-up study 6 years after installation - and the residents still reported no symptoms.
2. There was a disturbing smell in a wooden summer house built in 1964 which had been treated with chlorophenol-containing preservatives. At moist conditions chlorophenols may be biomethylated to form chloroanisoles having an intense mouldy odour. The ceiling, walls and floor in the bedroom, but not in the living-room, were covered with the barrier. Tetrachlorophenol, trichloroanisole, and pentachloroanisole were detected in the air of the living-room, but only tetrachlorophenol was found in the bedroom, at an air concentration 93% lower than in the living room. Also, the mouldy odour in the bedroom disappeared.
3. A building where a creosote-based tar layer had been attached onto the concrete slab as a moisture barrier was studied. The air concentration of polycyclic aromatic hydrocarbons (PAH) indoors was 1726 ng/m3 air. A disturbing PAH smell inside the building persisted even after the tar had been removed. After the barrier had been installed, on about 75 percent of the wall surface, the smell disappeared and the PAH air concentration decreased to 139 ng/m3 thus corresponding to a reduction of 92%.
In summary, use of an emissions barrier may provide an efficient, economic, quick, and environment-friendly way of ensuring a healthy indoor air.
Odour problems in buildings - the result of 682 cases
Mycoteam AS, Norway
Various odours can cause a negative perception of the indoor air quality. The intensity of the odour fluctuates for example due to weather conditions, ventilation, and use. In addition, the degree of odour perception among inhabitants is highly variable. Absence of an adequate measuring method make it difficult to get a systematic and uniform description of the odour and where in the building the odour is most noticeable. This leads to challenges in clarifying the causes and relevant mesures are often difficult to submit.
Examination of 420 cases with odour in dwellings and commercial buildings have shown that causes and remedial actions can be revealed by a systematic procedure. Those who complain are asked to characterize the smell in few, standardised words and describe where and when they experience the odour. This process normally takes from a few days to several weeks. The preliminary information is often crucial for the surveyor when performing the following building examination. In cases where the cause of the odour is detected, relevant actions is performed to eliminate the odour-source and thus the problem. Our surveys have shown that odour problems can be divided into seven main groups depending on the cause of the odour. These are in declining extent: mould and actinobacteria, sewage system, dead rodents, moist building materials, smoke, urine, and heating oil. In addition, there is a residual group of odour problems of unknown origin. Some odour problems were caused by a combination of several sources.
Intensity of odours reduces through time by natural decomposition. In cases where this process is time-consuming, active measures are needed. Which measures depend on the source of the odour, material properties and building physics. The optimal solution is removal of the odour source. Where this is not possible, a thorough cleaning can have a satisfactory effect. Use of ozone or products with odours to mask the problem usually have limited lasting effect.
Measuring odour is difficult and complicated for various reasons: the human olfactory organ is extremely sensitive and even small particles or molecules can be detected by the human nose. The results of for instance chemical measures such as VOC (volatile organic compounds), normally give a low result despite a distinct smell at the location. Chemical measures on a molecular level can be carried out, but the result is in most cases hard to interpret and rarely lead to the actual cause of the odour.
The effect of Relative Humidity on the Emission of Volatile Organic Compounds (VOCs) from Building Materials
1IMT Lille Douai, Institut Mines-Télécom, University of Lille, Centre for Energy and Environment, rue Charles Bourseul, 59500 Douai, France; 2IMT Atlantique, GEPEA UMR CNRS 6144, rue Alfred Kastler, 44300 Nantes, France; 3Cerema, 44 ter rue Jean Bart, 59000 Lille, France
The presence of Volatile Organic Compounds (VOCs) in indoor environments affects greatly indoor air Quality (IAQ) and can cause severe human health effects. Building and consumer materials are considered a major source of VOC emissions. The internal structure of walls in France is mainly composed of vapor barrier for damp proofing, thermal and acoustic insulating material, and plasterboard for fire protection and insulation which are potential sources of indoor VOCs. Moreover, the emission of VOCs from these materials is many-factor dependent among which relative humidity (RH) has a significant effect. Recently, bio-based insulations have been replacing conventional ones for their lower energy consumption during production; however, studies on their emissivity at different RH values are still not well developed.
The effect of RH on the emission of VOCs from commercially bought vapor barrier, glass and wood wools, and plasterboards has been characterized in this study. This was done by placing each material in the CLIMPAQ at 50% RH for 28 days and then increasing RH to 85% for another 28 days. VOCs and aldehydes measurements took place based on the ISO 16000 series.
A total of about 90 compounds was identified and quantified from the different materials including aldehydes, ketones, carboxylic acids, terpenes, and microbial VOCs. Among the studied materials, wood wool, which is the only bio-sourced material, is the most emissive where the emission rate (ER) of Total VOCs (TVOCs) is 69.8 µg/m2.h at 85% RH, followed by the vapor barrier (64.6 µg/m2.h), plasterboard (47.8 µg/m2.h), and glass wool (2.3 µg/m2.h). Moreover, the emission of VOCs and aldehydes from these materials was greatly affected by the change in RH. ERs of TVOCs and carbonyls emitted from the four materials were multiplied by about 2 to 10 times upon increasing RH from 50 to 85%.
Building products constitute a major source of indoor pollutants, especially at high humidity levels. Moreover, even if bio-sourced insulating materials might be energetically a good substituent for mineral-based materials, their impact on IAQ must be taken into consideration.
Further Development of Odour Testing of Building Products – Sample Presentation and Evaluation of Perceived Intensity
1University of Applied Sciences (HTW Berlin), Germany; 2Federal Institute for Materials Research and Testing (BAM), Germany; 3German Environment Agency (UBA), Germany
The indoor air quality is affected among other by the emission of volatile organic compounds (VOC) or the odour from building products. Odours can be measured by applying the standard DIN ISO 16000-28 (2020) "Indoor air - Part 28: Determination of odour emissions from building products using test chamber".
In the study presented here proposals for further technical development of the ISO 16000-28 (2020) method should be prepared. Especially the sampling procedure (1) and the evaluation method (2) of the perceived intensity are examined because they have a major influence on reproducibility of measurement results.
(1) Sampling procedure: Since the ISO was revised end of last year, the standard procedure for odour assessment by using containers is established. Direct assessment is with most common test chambers with volumes up to 1 m³ not possible because they are typically operated with an air outlet of less than 0.14 L/s. Due to the fact that 0.6 to 0.9 L/s is necessary for odour measurements this is not enough. An adapter for air sample collection and presentation to the panel will be developed, built and tested. The aim is to shorten time between sampling and presentation and to avoid transport of sensitive air samples, what can reduce measurement errors.
(2) Evaluation method: In Germany the AgBB demand a pi value of 7 pi for products to be suited for the indoor use. A method to simplify the evaluation of perceived intensity on a comparative scale is examined to test its suitability. The results shell help to increase acceptance of the evaluation with perceived intensity and to be able to determine odours from building products more and more precise by following objective evaluation criteria.
The research topic and first results will be presented at the conference.
Discerning relative humidity trends in vernacular and conventional building typologies for occupant health
1Indian Institute of Science, India; 2University of Bath, United Kingdom
The indoor built environment has a significant impact on the occupant's physiological, psychological, and behavioral health. Moisture is an important parameter that has a direct bearing on the quality of a built environment. Commonly referred to as water, moisture impacts nearly all dimensions of a building's functional performance, i.e., structural, durability, thermal, acoustics, indoor air quality, ventilation/freshness/odor, aesthetics, and also influences the health of occupants. Very high humidity can cause physical and chemical deterioration of materials, increased action of biological contaminants, and accelerate the spread of infections. However, low humidity can result in breathing difficulties, cough, irritation in the eye, wheeze, skin chapping, etc.
Building materials have an impact on indoor air quality. Vernacular building materials are often effective in regulating the thermal performance of a building, ensuring energy efficiency. Also, people residing in such dwellings have been found to have high resilience to withstand the adverse external
conditions. This exploratory study aims to understand the performance of building materials for the regulation of indoor moisture and air quality for promoting the health and well-being of the building and the occupants. The study involves monitoring a conventional (brick, concrete) dwelling and vernacular dwellings (adobe construction, brick/lime construction) situated in India's Composite Climatic zone. The result suggests that dwelling constructed with earth (adobe) maintains the narrowest range of variation in indoor relative humidity. The indoor relative humidity variation range is widest in cement concrete construction.
The paper examines factors that regulate relative humidity in the indoor environment. Understanding the moisture buffering capacity of the building materials in indoor RH regulation for occupant health has also been discussed.
Evaluation of the physiological effect on human subjects of different odorant environments
1PULSE Laboratory, CSTB Nantes, France; 2CSTB Grenoble, France
Different molecules or combinations of molecules can be used to formulate odorant products. Even if the commonly used methodology involving expert panelists is designed to reduce interindividual differences, the odorant sensitivity differs from one person to another. In this study, the physiological effect of different odorants was investigated by using sensory and physiological measurements. Chemical measurements of the exposure environment were also made simultaneously. The objective was to investigate the benefits of the addition of physiological data to discriminate the effects of the different odorants and to link them to the declared perception of intensity and well-being, and to the chemical composition of the exposure environment.
Eight subjects, aged from 24 to 56, with a normal BMI, non-smokers, and having a high declared and measured sensitivity to odorant stimuli were selected among a larger representative sample.
Two odorant products were evaluated using self-assessment questionnaires and physiological measurements, as well as a neutral environment without odorant emission (E0). The first odorant (E1) was a deodorant with a verbena and lemon scent, the second one (E2) was a deodorant with a lavender scent.
The perceived intensity and its associated well-being were evaluated using two 11-points scales, at several times after starting the odorant emission in the test chamber.
The physiological responses which were measured were heart rate, skin blood flow, electrodermal response (EDR) and respiration rate.
The experiments took place into a specific test emission chamber of 30 m3, with controlled temperature and humidity. The subjects were exposed individually to the three different environments, in the test emission chamber for 15 minutes. The air in the chamber was sampled during the exposure in order to be chemically analyzed with GC techniques.
Results obtained from the sensory questionnaires show that there are significant differences between the three odorant environments. E0 was perceived significantly less intense and less pleasant than E1 and E2, E1 was perceived as the most pleasant. Tuckey’s multiple comparisons post-hoc test show that E0 and E2 were not significantly perceived as different in intensity but that E1 was perceived significantly higher in intensity.
Results also indicate significant differences between the odorants for all the physiological responses. Electrodermal response, heart rate, and skin blood flow were lower for E1 than for E0 and E2, and, on the contrary, breathing rate was significantly higher for E1 than for E0, E2 was intermediate on this indicator.
Monitoring Mold growth and VOC-emissions from Wood Wool insulation under unfavorable hygrothermal conditions
1IMT Lille Douai, Institut Mines-Télécom, University of Lille, Centre for Energy and Environment, rue Charles Bourseul, 59500 Douai, France; 2IMT Atlantique, GEPEA UMR CNRS 6144, rue Alfred Kastler, 44300 Nantes, France; 3LTI-University of Picardy Jules Verne, IUT Amiens, Avenue des Facultés-Le Bailly, 80025 Amiens, France; 4Cerema, 44 ter rue Jean Bart, 59000 Lille, France
Mold growth in damp environments has been recently cited as the cause of a wide range of human diseases, mainly allergic and respiratory problems. The growth of indoor-surface molds depends on a group of physical and chemical conditions. The presence of nutritive bio-based support, such as wood wool, at a high humidity level, is considered the most satisfactory medium for surface-mold development. The detection of Microbial Volatile Organic Compounds (mVOCs) in indoor environments is considered an important marker of mold formation. These compounds are formed in the metabolism of fungi and bacteria and were recently analyzed in indoor-air environments.
In order to characterize the development of micro-organisms in indoor environments, a wall of a similar building structure to those of the town-hall of Moncheaux in France was reproduced at scale1 for testing in the laboratory. It was placed under hygrothermal conditions (T=22°C and RH=70±5%) favoring the development of micro-organisms. After one month, a part of the wood wool insulator was inoculated for another month after spraying about 700 CFU/cm2 of fungi to evaluate the proliferation of micro-organisms under these conditions. Two Field and Laboratory Emission Cells (FLEC) were used to monitor the surface emissions of not only mVOCs but also Total VOCs (TVOCs) and aldehydes from the inoculated and non-inoculated surfaces.
Only three mVOCs were detected from both surfaces with low and approximately equal emission rates (ER) of less than 0.5 µg/m2.h. Moreover, no mold development was observed neither on the inoculated nor on the non-inoculated surfaces of the wood wool after one month of experimentation. This is confirmed by the constant CFU number obtained upon extraction of micro-organisms. Therefore, the detected mVOCs cannot be considered a reliable indicator of mold development. In addition to mVOCs, about 70 VOCs and aldehydes were quantified from both surfaces. The ERs of TVOCs and aldehydes were 90.3 and 8.6 µg/m2.h, respectively from the non-inoculated surface and 71.2 and 8.5 µg/m2.h from the inoculated one. The difference in emissions is about 20% indicating no significant effect of inoculation on the emission of these compounds; however, the slight decrease in the emission of TVOCs might be due to their depletion from the material with time.
The obtained results emphasize that relative humidity levels up to 75% are not sufficient for mold development on wood insulators. More unfavorable conditions should be tested to check the resistance of bio-based materials against mold growth.
Influence of wooden Flooring on Indoor Air Quality
PP Polymer AB, Sweden
Due to new environmental trends and restrictions and due to more interest in using renewable materials with circularity, wood has become an important group of building materials for such as flooring.
Since flooring materials uses relatively high amounts of adhesives mostly belonging to urea-formaldehyde (UF) and contain terpenes, it is of utmost interest to investigate how such materials influence the indoor air climate and thereby may cause health problems.
For this reason, we investigated several commercial flooring materials and found some very unexpected results. According to international Occupational Exposure Limit levels (OEL), aldehydes are very hazardous for health at incredibly low concentrations. They are also classified as human carcinogens according to EPA
In this presentation emission results and the ways to reduce or eliminate emissions will be discussed.
Indoor air 2-ethylhexanol levels in an office building after floor repair – a follow-up study
Raksystems Suomi, Finland
2-Ethylhexanol (2-EH) is a pollutant often found in indoor air. It can be emitted for example due to degradation of phtalate plasticizers used in polyvinyl chloride (PVC) floorings. Another significant source of 2-EH is ethyl-hexyl acrylate-containing adhesives. A prominent characteristic of 2-EH is the seasonal fluctuation of its indoor air concentration. The compound is detected at higher concentrations in high‐temperature and humid seasons and at markedly lower concentrations during winter.
2-EH may affect human health even at relatively low concentrations. It may provoke irritation of the respiratory tract and cause asthma-type symptoms at levels of exceeding 175 µg/m3. In any case, the detection of 2‐EH is a strong indicator of PVC flooring degradation and indirect proof of occupant exposure to possibly dangerous DEHP levels. 2-EH is also a potential marker for microbial growth.
Abnormally high levels (up to 25 µg/m3) of 2-EH were observed in indoor air of an office building one year after flooring renovation. In subsequent investigations, the adhesive was found to be the likely and dominant source of 2-EH. Material samples proved that 2-EH was penetrated only into the very top screed layer.
The flooring materials of the premises were reinstalled. The textile carpets were completely removed and the screed was grinded for at least 3 mm. The correct grinding depth was secured using material samples of the screed. After reinstallation, the emission of the new flooring materials is studied with air samples.
In this study, indoor air concentrations of VOCs in an office building are measured during one year. The air sampling is carried out in four stages: 1) one month after floor repair; 2) three months after repair; 3) six months after repair; 4) one year after repair. Samples are collected from across the premises at least in 10 different locations. One room without renovations was earmarked as a reference space. Measurements are performed with standard ventilation settings at a constant indoor air temperature. Altogether about 70 air samples will be collected. First results show that the indoor air 2-EH levels have decreased by about a half or more during the first three months after repair. More results will be presented at the conference.
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