Materials Science and Engineering C 36 (2014) 1–6
Contents lists available at ScienceDirect
Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec
Impact of indoor surface material on perceived air quality I. Senitkova ⁎ Technical and Economical University of Ceske Budejovice, Civil Engineering Department, Okruzní 10, 37001 Ceske Budejovice, Czech Republic
a r t i c l e
i n f o
Article history: Received 4 January 2013 Received in revised form 12 October 2013 Accepted 22 November 2013 Available online 6 December 2013 Keywords: Building surface materials Indoor odors Volatile organic compounds Material emissions Perceived indoor air quality
a b s t r a c t The material combination impact on perceived indoor air quality for various surface interior materials is presented in this paper. The chemical analysis and sensory assessments identifies health adverse of indoor air pollutants (TVOCs). In this study, emissions and odors from different common indoor surface materials were investigated in glass test chamber under standardized conditions. Chemical measurements (TVOC concentration) and sensory assessments (odor intensity, air acceptability) were done after building materials exposure to standardized conditions. The results of the chemical and sensory assessment of individual materials and their combinations are compared and discussed within the paper. The using possibility of individual material surface sorption ability was investigated. The knowledge of targeted sorption effects can be used in the interior design phase. The results demonstrate the various sorption abilities of various indoor materials as well as the various sorption abilities of the same indoor material in various combinations. © 2013 Elsevier B.V. All rights reserved.
1. Introduction The traditional way of material selection for building design has been primarily based on factors such as cost, aesthetic values, availability and durability. Many healthcare construction projects, including many of the case study profiles here, incorporate interior finishes and products characterized as “reduced or non-toxic,” low-VOC or PVCfree. All of the healthcare facilities completed their analysis and selection of the materials based on the intuitive assumption that they will reduce exposure of occupants to potentially dangerous or harmful chemicals. At the same time, the facilities have collected scant empirical data documenting any actual difference or benefit following the initial construction and commissioning phase. While this lack of data likely leads to underestimating benefits, most healthcare organizations proceed as part of “green building” initiatives and out of concern for people involved in building construction. Building materials can have a major impact on air quality and can affect occupants, especially sensitive ones including children, the elderly, and patients who are immunocompromised or have respiratory problems. Careful selection of materials along with proper ventilation, operation, and maintenance can improve air quality. The environmental impact, both on the environment and occupants, has not been addressed till very recently in Slovakia. Many of the materials used in buildings, either as interior materials or as furnishings, are the main sources of indoor air pollution in addition to those caused by humans and their activities and HVAC systexms. The important source is the indoor surface materials of building itself, which in many cases can result in great amounts of indoor volatile organic compounds ⁎ Tel.: +420 773697388; +421 903961491 (mob). E-mail address: [email protected]. 0928-4931/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.msec.2013.11.032
(VOCs), especially building material finishes (floors, walls and ceilings) which are considered to have an important role also in perceived indoor air quality. The ability to accurately evaluate volatile organic compound (VOC) emissions from indoor materials requires reliable and consistent chamber tests. The principle of the test method is to assess the emission of pollutants from a test specimen, prepared from a sample of a building material, by sensory assessments and concentration measurements of the air in a test chamber. The surface of the test specimen is exposed to the chamber air which is maintained at a temperature, humidity and air change similar to that which can be expected in an indoor environment in which the material is usually used. In addition to these conditions the chamber concentration depends on the supply airflow rate in the chamber and the area of the test specimen. The test should be performed with an area specific airflow rate similar to that which can be expected during the normal use of the material. However, previous chamber comparisons show significant variations among laboratory testing results [2,5,4]. One means of addressing these inconsistencies is by using a reference material with an independently known emission rate to evaluate the performance of a laboratory emission chamber. Previous tests have also shown that a chamber's environmental conditions of temperature and relative humidity have the potential to influence the emission of certain VOCs from building materials. Thus, if a chamber is not operating at the specified environmental set-points for a test, the emission rate results could vary. The research on the impact of indoor air conditions; temperature, relative humidity and surface air velocity on materials emission rates were done. The results indicate that both the temperature and relative humidity have a significant effect on the emissions from paint and varnish. In the case of varnish, the results were consistent with earlier results. However, the paint results show inconsistent emission behavior. Further,
2
I. Senitkova / Materials Science and Engineering C 36 (2014) 1–6
for both materials, the individual compounds did not necessarily follow the same trend established for the TVOC [3]. For example, previous research shows emissions of most VOC species from building materials to increase with increasing temperature, while the potential impact of relative humidity on VOC emissions from building materials is less clear [6,11,13]. Corresponding studies have been mainly conducted under a set of standard environmental conditions (25 ± 1 °C, 50 ± 5% relative humidity and 1 air change per hour (ACH)). However, the conditions around a material in actual buildings are usually different from such standard conditions. The complexity in evaluating the indoor air quality can be provided by chemical and sensory assessment under various building operating conditions. The published sensory assessment results showed that the exposure response relationship varies for one of the tested materials compared with the others. The study also confirmed that interaction among building materials is often negligible from the perception point of view, which is in contradiction with other published findings. The analysis of data indicated that linear addition of olfs of single materials is still a permissible simplified method to estimate the sensory pollution load in the presence of combinations of building materials in the absence of any other practical technique [12]. Indoor surface materials can act as sorbents or sources of VOC emission. The pollutants emitted from one material can be sorbed on the surfaces of other materials. That results in reducing the concentration of sensory pollutants and improving the perceived air quality. The porous materials have significant sorption effect on the VOCs. When sinks becomes saturated, sorption no longer influences the perceived air quality and when the environmental conditions change, the sinks in a space can act as net emission sources [7,8]. The sorption of volatile organic compounds (VOCs) on material surfaces was evaluated by chamber testing. The sorption of single VOCs was compared to the sorption of the combination of the VOCs and the sorption of single material surfaces was compared to the sorption of the combination of material surfaces. The results of the material surfaces (wool carpet and nylon carpet) sorption show that the loading has no influence by itself. Relatively high loading minimizes the sink effects of the test chamber and is therefore recommended. The sink effect of the chambers and the effect of the loading of the materials were evaluated separately. Relatively high loading minimizes the sink effects of the test chamber and is therefore recommended [1,8]. Nowadays the research project activity of indoor environmental engineering groups is focused on indoor air sciences. Especially, perceived air quality observation focused on selected chemicals occurrences in working environments have shown that mainly office buildings have high levels of pollution related to interior materials [9,10]. In this study emissions and odors from commonly used surface materials were investigated. The test chamber for chemical measurements (TVOCs) and subjective sensory assessments were used. The surface materials used in this study were selected to present major surface coverings used indoors in Slovak offices. The results of an experimental procedure to observe the impact of building materials on perceived air quality are presented. An untrained panel perceived the quality of polluted air in small-scale chamber settings. The air pollution was generated by emissions from individual materials, by combinations of these materials and by mixtures of emissions from single materials.
Table 1 Tested materials. Construction
Type of samples
Floor
PVC HDF PA OSB PGB PVCW
Walls/ceiling
measurements (VOC concentration) and sensory assessments (odor intensity, air acceptability) were done under standardized conditions (25 ± 1 °C and 50 ± 5% relative humidity and 1air changes per hour). The standardized conditions were controlled by parameters of supply air. The measurements were conducted in a test chamber made of glass with a volume of 190 l (Fig. 1). The test method principle is to assess the emission of pollutants from a test specimen, prepared from a sample of a building material, by sensory assessments and concentration measurements of the air in a test chamber. The surface of the test specimen is exposed to the chamber air which is maintained at a temperature, humidity and velocity similar to that which can be expected in the indoor environment in which the material is usually used. In addition to these conditions the chamber concentration depends on the supply airflow rate in the chamber and the area of the test specimen. The test is performed with an area specific airflow rate similar to that which can be expected during the normal use of the material. The samples of building materials were placed in the test chamber. Before the tests, the chamber was cleaned and the background concentration of pollutants and sensory assessment in an empty chamber operated under the same conditions as during the emission test were investigated. The mean air velocity and air flow rate were measured with a thermal anemometer TESTO 425. The building materials were wrapped in aluminum foil and polyethylene foil and stored at controlled conditions. The measurements were done on the 3rd day of tested material exposure to standardized conditions (25 ± 1 °C and 50 ± 5% relative humidity). The air velocity over the building product samples was adjusted to 0.1–0.2 m/s corresponding to a realistic indoor range. The sizes of the test specimens were determined so that the area specific airflow rate in the test chamber corresponded to the area specific airflow rate in standard model room (3.2 × 2.2 × 2.4 m). The specimens were placed vertically, so that the emission surfaces were parallel to the direction of the air flow. All of the surfaces except the emission surfaces were covered with aluminum foil.
2. Experimental methodology The TVOC concentration and odor emissions from four floor coverings and two walls and/or ceiling coverings were investigated as shown in Table 1. Polyvinyl chloride (PVC), high density fiber board laminate (HDF), polyamide carpet (PA) and oriented strand boards (OSB) were investigated as typical flooring covering. Painted gypsum board (PGB) and polyvinyl chloride wallpaper (PVCW) as wall and ceiling coating materials were used for studied combinations. The chemical
F1 F2 F3 F4 W1 W2
Fig. 1. Test chamber.
I. Senitkova / Materials Science and Engineering C 36 (2014) 1–6
The chemical analysis was based on the detection of selected volatile organic compounds. An active sampling of VOCs was performed by using a pump (Aircheck 2000) with an air flow rate of 400 ml/min on charcoal tubes ORBO 32S (Supelco) during 24 h. The absorbed VOCs were analyzed by gas chromatography (GC Varian 3 300) after extraction into carbon disulphide. The sum of the VOCs was calculated based on individual VOC concentrations including unidentified peak areas converted to decane equivalents (equivalent to toluene). In the study, the recommended TVOCs comfort value 200 μg/m3 was used. The value represents a critical approach to the indoor air quality assessment. The exhaust air from test chamber was led through a diffuser for sensory assessments. An untrained sensory panel of 25 subjects assessed odor intensity and perceived air quality. Before the first assessment the panels were instructed how to use the scale and the exposure equipment. The responsible person of the experiment assessed each subject's attitude and motivation concerning the experiment and subject's personal hygiene. There was no restriction on distribution of gender or smoking habits. The age ranged from 20 to 40 years with mean a 30 years, and 20% of the subjects were smokers. The panel stayed in the good ventilated room without odors before the assessments. Then the subjects indicated their immediate evaluation on two continuous scales regarding odor intensity (0 no odor–5 overwhelming odor) and acceptability of the air (−1 clearly unacceptable, +1 clearly acceptable) from which the percentage of dissatisfaction was estimated. The standard test method was used for the calculation of acceptability and the estimation of odor intensity. During the measurements, the test chambers were covered with aluminum sheets to hide the building products from the view of the sensory panels. The sensory assessment results are expressed as mean odor intensity (OI) and air acceptability (AA). The results are introduced for the individual flooring materials (F1, F2, F3, F4) and for the individual wall/ceiling coverings (W1, W2) as well as for their combinations. 3. Results and discussion 3.1. Sensory assessment The sensory assessment expressed as mean odor intensity and air acceptability is shown in Figs. 2–5. The results are introduced for the individual flooring materials (F1, F2, F3, F4) and for their combinations with wall/ceiling coverings (W1, W2). 3.1.1. Individual materials sensory assessment Concerning individual materials, the highest odor intensity as well as dissatisfaction with perceived air quality was from the OSB boards flooring covering. In the case of walls and ceiling surface materials the
3
PVC wall coating material was the most unacceptable. Only the carpet and painted gypsum boards caused lower odor intensities then 2—moderate odor, however the perceived air acceptability was in all cases of tested surface materials unacceptable. The summary of sensory assessment results for individual tested materials along with percentage of dissatisfied are shown in Table 2. 3.1.2. Material combination sensory assessment The air acceptability was perceived as more acceptable for flooring materials with an addition of painted gypsum boards (W1/F1, W1/F2, W1/F3) compared to the air acceptability of the individual flooring materials. The acceptability was found not so high compared to that for painted gypsum board separately. For the acceptability for OSB boards with an addition of painted gypsum boards (W1/F4), no positive impact was noticed. The tested air was perceived less acceptable for flooring materials with additions of PVC wall paper (W2/F1, W2/F2, W2/F3) than those ones individually. The acceptability was lower than that for PVC wallpaper separately. No positive impact was noticed for the OSB boards with an addition of PVC wallpaper (W2/F4) in the acceptability assessment. The acceptable perceived air quality was not reached by any material combinations. The odor intensity was perceived as lower for flooring materials with an addition of painted gypsum boards (W1/F1, W1/F2) compared to individually tested flooring materials F1 and F2. In the case of the W1/F3 combination the odor intensity was almost the same as that of the individual materials. The odor intensity for combination W1/F4 was a little bit lower than for OSB boards individually but was higher than for gypsum boards individually. It seems that the positive impact of gypsum boards was not sufficient enough by tested period. The value of odor intensity for combinations W2/F1, W2/F2 and W2/F3 was between the odor intensity values of separately tested floor materials. No positive impact was noticed for the OSB boards with an addition of PVC wallpaper (W2/F4) in the odor intensity assessment. The recommended odor intensity was not reached by any material combinations. Comparing the results obtained by odor intensity scale and acceptability scale, it was found that they correspond to each other. 3.2. Chemical assessment Chemical assessment for the individual flooring materials (F1, F2, F3, F4) and their combinations with wall/ceiling coverings (W1, W2) is shown within Figs. 6–9. 3.2.1. Individual materials chemical assessment Concerning individual materials, the highest TVOC value was found for OSB board flooring. The results of chemical assessments for OSB
Fig. 2. Sensory assessment (F1, W1, W2).
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I. Senitkova / Materials Science and Engineering C 36 (2014) 1–6
Fig. 3. Sensory assessment (F2, W1, W2).
boards correspond to results of sensory assessments. TVOC concentration from wall/ceiling construction materials was pretty much higher for tested painted gypsum boards than for PVC wallpaper. The TVOC concentrations for painted gypsum boards were relatively high (534 μg/m3 ); the highest value was estimated only for OSB boards (1080 μg/m3 ). But the odor intensity and air acceptability for painted gypsum boards were acceptable. On the other hand the worst acceptability was caused by PVC wallpaper but the lowest TVOC concentration (168 μg/m3) was found. The value of TVOC concentration for high density fiber board laminate flooring is slightly above comfort level. The TVOC value was pretty under 200 μg/m 3 comfort value (Molhave) for PA carpet covering (121 μg/m3).
3.3. Material combination chemical effect The studied effect of material combinations to chemical assessment expressed by TVOC concentration was markedly positive for PVC flooring and painted gypsum board (W1/F1) with regard to both individual tested materials. The F1 TVOC concentration (532 μg/m3) was very similar to the W1 TVOC concentration (534 μg/m3). The decrease for the W1/F1 combination was nearly 50% even if the final value was slightly above comfort value. The decrease for the W2/F1 combination was only 30%. Following these results the PVC flooring is more effective combined with painted gypsum board walls than with PVC wallpapers (Fig. 6). It is better to combine the laminate flooring of high density fiber boards with wallpapers. Also for the combination with painted
gypsum boards (W1/F2) the nearly 400 μg/m3 value was obtained but the laminate flooring combination with wallpaper (W2/F2) is more preferable (Fig. 7). Similar results for PA carpeting combinations were confirmed (Fig. 8). The markedly negative effect was found for combination of OSB boards and painted gypsum boards (W1/F4) with regard to both individual tested materials as well as for the combination of OSB and wallpaper (W2/F4). As seen in Fig. 9 both values for combinations are quite high.
4. Discussion The selection of the materials in Slovakia is strongly based on the intuitive assumption that they will reduce exposure of occupants to potentially dangerous or harmful chemicals. This is the first paper that examines the concentration exposure of VOC and odor perceiving in indoor air of interior materials typically used in Slovakia. By all studied material combinations the TVOC concentration decrease was obtained only with regard to one of the tested materials. The emissions from tested surface materials and their combinations are considered important as no acceptability was found. The most important indoor odor sources were the determined materials based on PVC and OSB boards. Several tested materials and their combinations were slightly unacceptable and by some testing were almost clearly unacceptable. Basically the majority of the tested materials combinations resulted to an improvement in sensory and chemical environmental ratings. No specified reason to impact material interaction effects on perceived air quality was found.
Fig. 4. Sensory assessment (F3, W1, W2).
I. Senitkova / Materials Science and Engineering C 36 (2014) 1–6
5
Fig. 5. Sensory assessment (F4, W1, W2).
1400
Table 2 Sensory assessment of tested indoor materials. AA (−1;+1)
OI (0;5)
PN [%]
F1 F2 F3 F4 W1 W2
−0.39 −0.38 −0.32 −0.62 −0.17 −0.73
2.15 2.21 1.79 3.21 1.77 3.19
87 84 65 96 65 98
TVOC [µg/m3]
1200 Indoor material
1000 800 600 400 200 0 F3
1400
W2
W1/F3
W2/F3
Fig. 8. Chemical analysis (F3, W1, W2).
1200 1000 1400 800 1200
600 400 200 0 F1
W1
W2
W1/F1
W2/F1
TVOC [µg/m3]
TVOC [µg/m3]
W1
1000 800 600 400
Fig. 6. Chemical analysis (F1, W1, W2).
200 0 F4
1400
W2
W1/F4
W2/F4
Fig. 9. Chemical analysis (F4, W1, W2).
1200
TVOC [µg/m3]
W1
1000
Table 3 Sensory assessments vs. chemical analysis.
800
Combination
600
PGB
400 200
PVCW
0 F2
W1
W2
W1/F2
Fig. 7. Chemical analysis (F2, W1, W2).
W2/F2
PVC HDF PA OSB PVC HDF PA OSB
CTVOC [μg/m3]
Air acceptability
Odor intensity
✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓
✓ ✓ ✓ ✗ ✓ ✓ ✓ ✗
✓ ✓ ✓ ✗ ✓ ✓ ✓ ✗
✓, positive effect; ✗, no effect.
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The strongest effect of material interaction was found by combinations with painted gypsum boards. No positive effect on perceived air quality was found for the tested material combinations with OSB boards (Table 3). The necessity of parallel chemical and sensory analyses of indoor air quality was confirmed. On the basis of the results, it is possible to assume that the human nose is much more sensitive than chemical testing procedures. Both methods used in parallel, chemical testing and sensory measurements, are equally useful for perceived air quality assessment and providing important information about the acceptability of building materials for indoor use. The purpose of sensory assessment is to consider influence of indoor air quality to wellbeing.
5. Conclusion The interior surface material emissions and odors were investigated in a glass test chamber. The aimed material combinations impact on air quality was reported and the positive effects of selected material combinations were recognized. The significant impact of indoor surface materials on perceived air quality as well as generally the positive interaction effect was confirmed. Both, methods used in parallel, chemical testing and sensory measurements, are equally useful for perceived air quality assessment and providing important information about the acceptability of indoor materials. The main purpose of sensory assessment is to consider and mainly respect the influence of indoor air quality to human wellbeing. In order to guarantee acceptable indoor air quality the identification of all important indoor odor sources is required. The measure of indoor air pollution decreasing is the effective material control. Demand control material selection seems to be the most important approach in building design with respect to perceived indoor air quality and green building concept.
Acknowledgments The authors are grateful to the Slovak Grant Agency for supporting. References [1] O. Bjorseth, Sorption behavior of volatile organic compounds on material surfaces— the influence of combinations of compounds and materials compared to sorption of single compounds on single materials, Environ. Int. 25 (1999) 17–27. [2] M. Bortoli, S. Kephalopoulos, S. Kirchner, H. Schauenburg, H. Vissers, State-of the-art in the measurement of volatile organic compounds emitted from building products: results of European interlaboratory comparison, Indoor Air 9 (1999) 103–116. [3] F. Haghighat, L. Bellis, Material emission rates: literature review, and the impact of indoor air temperature and relative humidity, Build. Environ. 33 (1998) 261–277. [4] W. Horn, O. Wilke, K. Wiegner, Results of RR-VOC-BAM_2009, Final Report. BAM, Federal Institute for Materials Research and Testing, Berlin, 2010. [5] C. Howard-Reed, S.J. Nabinger, Developing a standard reference material for VOC emissions testing, Proceedings of the Indoor Environmental Quality: Problems, Research and Solutions Conference (113–119), Research Triangle Park NC: EPA/AWMA, 2006. [6] C.C. Lin, K.P. Yu, P. Zhao, G.W. Lee, Evaluation of impact factors on VOC emissions and concentrations from wooden flooring based on chamber tests, Build. Environ. 44 (2009) 525–533. [7] J. Popa, F. Haghighat, Characterization of the sink effect of VOCs on building materials, with specific emphasis on painted surfaces, Proceeding of Indoor Air 2002, Concordia University, Montreal, 2002, pp. 558–563. [8] W. Sakr, et al., The impact of building materials and their combinations on perceived air quality, Proceedings of Healthy Buildings 2000, Concordia University, Canada, Danish Building Research institute, Denmark, 2000, p. 79. [9] W. Sakr, et al., Sorptive interactions among building materials and their resultant impact on perceived indoor air quality, Proceedings of Indoor Air 2005, Beijing, 2005, pp. 1–5. [10] I. Senitkova, T. Tomcik, Interior materials impact to indoor air quality, Adv. Sci. Lett. 19 (3) (2013) 955–959. [11] Y.P. Zhang, X.X. Luo, X.K. Wang, K. Qian, R.Y. Zhao, Influence of temperature on formaldehyde emission parameters of dry building materials, Atmos. Environ. 41 (2007) 3203–3216. [12] B. Yeganeh, F. Haghighat, L. Gunarsen, A. Afshari, H. Knudsen, Evaluation of building materials individually and in combination using odour threshold, Indoor Build. Environ. 15 (2006) 583–593. [13] P. Wolkoff, Impact of air velocity, temperature, humidity, and air on long-term VOC emissions from building products, Atmos. Environ. 32 (1998) 2659–2668.
Contents lists available at ScienceDirect
Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec
Impact of indoor surface material on perceived air quality I. Senitkova ⁎ Technical and Economical University of Ceske Budejovice, Civil Engineering Department, Okruzní 10, 37001 Ceske Budejovice, Czech Republic
a r t i c l e
i n f o
Article history: Received 4 January 2013 Received in revised form 12 October 2013 Accepted 22 November 2013 Available online 6 December 2013 Keywords: Building surface materials Indoor odors Volatile organic compounds Material emissions Perceived indoor air quality
a b s t r a c t The material combination impact on perceived indoor air quality for various surface interior materials is presented in this paper. The chemical analysis and sensory assessments identifies health adverse of indoor air pollutants (TVOCs). In this study, emissions and odors from different common indoor surface materials were investigated in glass test chamber under standardized conditions. Chemical measurements (TVOC concentration) and sensory assessments (odor intensity, air acceptability) were done after building materials exposure to standardized conditions. The results of the chemical and sensory assessment of individual materials and their combinations are compared and discussed within the paper. The using possibility of individual material surface sorption ability was investigated. The knowledge of targeted sorption effects can be used in the interior design phase. The results demonstrate the various sorption abilities of various indoor materials as well as the various sorption abilities of the same indoor material in various combinations. © 2013 Elsevier B.V. All rights reserved.
1. Introduction The traditional way of material selection for building design has been primarily based on factors such as cost, aesthetic values, availability and durability. Many healthcare construction projects, including many of the case study profiles here, incorporate interior finishes and products characterized as “reduced or non-toxic,” low-VOC or PVCfree. All of the healthcare facilities completed their analysis and selection of the materials based on the intuitive assumption that they will reduce exposure of occupants to potentially dangerous or harmful chemicals. At the same time, the facilities have collected scant empirical data documenting any actual difference or benefit following the initial construction and commissioning phase. While this lack of data likely leads to underestimating benefits, most healthcare organizations proceed as part of “green building” initiatives and out of concern for people involved in building construction. Building materials can have a major impact on air quality and can affect occupants, especially sensitive ones including children, the elderly, and patients who are immunocompromised or have respiratory problems. Careful selection of materials along with proper ventilation, operation, and maintenance can improve air quality. The environmental impact, both on the environment and occupants, has not been addressed till very recently in Slovakia. Many of the materials used in buildings, either as interior materials or as furnishings, are the main sources of indoor air pollution in addition to those caused by humans and their activities and HVAC systexms. The important source is the indoor surface materials of building itself, which in many cases can result in great amounts of indoor volatile organic compounds ⁎ Tel.: +420 773697388; +421 903961491 (mob). E-mail address: [email protected]. 0928-4931/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.msec.2013.11.032
(VOCs), especially building material finishes (floors, walls and ceilings) which are considered to have an important role also in perceived indoor air quality. The ability to accurately evaluate volatile organic compound (VOC) emissions from indoor materials requires reliable and consistent chamber tests. The principle of the test method is to assess the emission of pollutants from a test specimen, prepared from a sample of a building material, by sensory assessments and concentration measurements of the air in a test chamber. The surface of the test specimen is exposed to the chamber air which is maintained at a temperature, humidity and air change similar to that which can be expected in an indoor environment in which the material is usually used. In addition to these conditions the chamber concentration depends on the supply airflow rate in the chamber and the area of the test specimen. The test should be performed with an area specific airflow rate similar to that which can be expected during the normal use of the material. However, previous chamber comparisons show significant variations among laboratory testing results [2,5,4]. One means of addressing these inconsistencies is by using a reference material with an independently known emission rate to evaluate the performance of a laboratory emission chamber. Previous tests have also shown that a chamber's environmental conditions of temperature and relative humidity have the potential to influence the emission of certain VOCs from building materials. Thus, if a chamber is not operating at the specified environmental set-points for a test, the emission rate results could vary. The research on the impact of indoor air conditions; temperature, relative humidity and surface air velocity on materials emission rates were done. The results indicate that both the temperature and relative humidity have a significant effect on the emissions from paint and varnish. In the case of varnish, the results were consistent with earlier results. However, the paint results show inconsistent emission behavior. Further,
2
I. Senitkova / Materials Science and Engineering C 36 (2014) 1–6
for both materials, the individual compounds did not necessarily follow the same trend established for the TVOC [3]. For example, previous research shows emissions of most VOC species from building materials to increase with increasing temperature, while the potential impact of relative humidity on VOC emissions from building materials is less clear [6,11,13]. Corresponding studies have been mainly conducted under a set of standard environmental conditions (25 ± 1 °C, 50 ± 5% relative humidity and 1 air change per hour (ACH)). However, the conditions around a material in actual buildings are usually different from such standard conditions. The complexity in evaluating the indoor air quality can be provided by chemical and sensory assessment under various building operating conditions. The published sensory assessment results showed that the exposure response relationship varies for one of the tested materials compared with the others. The study also confirmed that interaction among building materials is often negligible from the perception point of view, which is in contradiction with other published findings. The analysis of data indicated that linear addition of olfs of single materials is still a permissible simplified method to estimate the sensory pollution load in the presence of combinations of building materials in the absence of any other practical technique [12]. Indoor surface materials can act as sorbents or sources of VOC emission. The pollutants emitted from one material can be sorbed on the surfaces of other materials. That results in reducing the concentration of sensory pollutants and improving the perceived air quality. The porous materials have significant sorption effect on the VOCs. When sinks becomes saturated, sorption no longer influences the perceived air quality and when the environmental conditions change, the sinks in a space can act as net emission sources [7,8]. The sorption of volatile organic compounds (VOCs) on material surfaces was evaluated by chamber testing. The sorption of single VOCs was compared to the sorption of the combination of the VOCs and the sorption of single material surfaces was compared to the sorption of the combination of material surfaces. The results of the material surfaces (wool carpet and nylon carpet) sorption show that the loading has no influence by itself. Relatively high loading minimizes the sink effects of the test chamber and is therefore recommended. The sink effect of the chambers and the effect of the loading of the materials were evaluated separately. Relatively high loading minimizes the sink effects of the test chamber and is therefore recommended [1,8]. Nowadays the research project activity of indoor environmental engineering groups is focused on indoor air sciences. Especially, perceived air quality observation focused on selected chemicals occurrences in working environments have shown that mainly office buildings have high levels of pollution related to interior materials [9,10]. In this study emissions and odors from commonly used surface materials were investigated. The test chamber for chemical measurements (TVOCs) and subjective sensory assessments were used. The surface materials used in this study were selected to present major surface coverings used indoors in Slovak offices. The results of an experimental procedure to observe the impact of building materials on perceived air quality are presented. An untrained panel perceived the quality of polluted air in small-scale chamber settings. The air pollution was generated by emissions from individual materials, by combinations of these materials and by mixtures of emissions from single materials.
Table 1 Tested materials. Construction
Type of samples
Floor
PVC HDF PA OSB PGB PVCW
Walls/ceiling
measurements (VOC concentration) and sensory assessments (odor intensity, air acceptability) were done under standardized conditions (25 ± 1 °C and 50 ± 5% relative humidity and 1air changes per hour). The standardized conditions were controlled by parameters of supply air. The measurements were conducted in a test chamber made of glass with a volume of 190 l (Fig. 1). The test method principle is to assess the emission of pollutants from a test specimen, prepared from a sample of a building material, by sensory assessments and concentration measurements of the air in a test chamber. The surface of the test specimen is exposed to the chamber air which is maintained at a temperature, humidity and velocity similar to that which can be expected in the indoor environment in which the material is usually used. In addition to these conditions the chamber concentration depends on the supply airflow rate in the chamber and the area of the test specimen. The test is performed with an area specific airflow rate similar to that which can be expected during the normal use of the material. The samples of building materials were placed in the test chamber. Before the tests, the chamber was cleaned and the background concentration of pollutants and sensory assessment in an empty chamber operated under the same conditions as during the emission test were investigated. The mean air velocity and air flow rate were measured with a thermal anemometer TESTO 425. The building materials were wrapped in aluminum foil and polyethylene foil and stored at controlled conditions. The measurements were done on the 3rd day of tested material exposure to standardized conditions (25 ± 1 °C and 50 ± 5% relative humidity). The air velocity over the building product samples was adjusted to 0.1–0.2 m/s corresponding to a realistic indoor range. The sizes of the test specimens were determined so that the area specific airflow rate in the test chamber corresponded to the area specific airflow rate in standard model room (3.2 × 2.2 × 2.4 m). The specimens were placed vertically, so that the emission surfaces were parallel to the direction of the air flow. All of the surfaces except the emission surfaces were covered with aluminum foil.
2. Experimental methodology The TVOC concentration and odor emissions from four floor coverings and two walls and/or ceiling coverings were investigated as shown in Table 1. Polyvinyl chloride (PVC), high density fiber board laminate (HDF), polyamide carpet (PA) and oriented strand boards (OSB) were investigated as typical flooring covering. Painted gypsum board (PGB) and polyvinyl chloride wallpaper (PVCW) as wall and ceiling coating materials were used for studied combinations. The chemical
F1 F2 F3 F4 W1 W2
Fig. 1. Test chamber.
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The chemical analysis was based on the detection of selected volatile organic compounds. An active sampling of VOCs was performed by using a pump (Aircheck 2000) with an air flow rate of 400 ml/min on charcoal tubes ORBO 32S (Supelco) during 24 h. The absorbed VOCs were analyzed by gas chromatography (GC Varian 3 300) after extraction into carbon disulphide. The sum of the VOCs was calculated based on individual VOC concentrations including unidentified peak areas converted to decane equivalents (equivalent to toluene). In the study, the recommended TVOCs comfort value 200 μg/m3 was used. The value represents a critical approach to the indoor air quality assessment. The exhaust air from test chamber was led through a diffuser for sensory assessments. An untrained sensory panel of 25 subjects assessed odor intensity and perceived air quality. Before the first assessment the panels were instructed how to use the scale and the exposure equipment. The responsible person of the experiment assessed each subject's attitude and motivation concerning the experiment and subject's personal hygiene. There was no restriction on distribution of gender or smoking habits. The age ranged from 20 to 40 years with mean a 30 years, and 20% of the subjects were smokers. The panel stayed in the good ventilated room without odors before the assessments. Then the subjects indicated their immediate evaluation on two continuous scales regarding odor intensity (0 no odor–5 overwhelming odor) and acceptability of the air (−1 clearly unacceptable, +1 clearly acceptable) from which the percentage of dissatisfaction was estimated. The standard test method was used for the calculation of acceptability and the estimation of odor intensity. During the measurements, the test chambers were covered with aluminum sheets to hide the building products from the view of the sensory panels. The sensory assessment results are expressed as mean odor intensity (OI) and air acceptability (AA). The results are introduced for the individual flooring materials (F1, F2, F3, F4) and for the individual wall/ceiling coverings (W1, W2) as well as for their combinations. 3. Results and discussion 3.1. Sensory assessment The sensory assessment expressed as mean odor intensity and air acceptability is shown in Figs. 2–5. The results are introduced for the individual flooring materials (F1, F2, F3, F4) and for their combinations with wall/ceiling coverings (W1, W2). 3.1.1. Individual materials sensory assessment Concerning individual materials, the highest odor intensity as well as dissatisfaction with perceived air quality was from the OSB boards flooring covering. In the case of walls and ceiling surface materials the
3
PVC wall coating material was the most unacceptable. Only the carpet and painted gypsum boards caused lower odor intensities then 2—moderate odor, however the perceived air acceptability was in all cases of tested surface materials unacceptable. The summary of sensory assessment results for individual tested materials along with percentage of dissatisfied are shown in Table 2. 3.1.2. Material combination sensory assessment The air acceptability was perceived as more acceptable for flooring materials with an addition of painted gypsum boards (W1/F1, W1/F2, W1/F3) compared to the air acceptability of the individual flooring materials. The acceptability was found not so high compared to that for painted gypsum board separately. For the acceptability for OSB boards with an addition of painted gypsum boards (W1/F4), no positive impact was noticed. The tested air was perceived less acceptable for flooring materials with additions of PVC wall paper (W2/F1, W2/F2, W2/F3) than those ones individually. The acceptability was lower than that for PVC wallpaper separately. No positive impact was noticed for the OSB boards with an addition of PVC wallpaper (W2/F4) in the acceptability assessment. The acceptable perceived air quality was not reached by any material combinations. The odor intensity was perceived as lower for flooring materials with an addition of painted gypsum boards (W1/F1, W1/F2) compared to individually tested flooring materials F1 and F2. In the case of the W1/F3 combination the odor intensity was almost the same as that of the individual materials. The odor intensity for combination W1/F4 was a little bit lower than for OSB boards individually but was higher than for gypsum boards individually. It seems that the positive impact of gypsum boards was not sufficient enough by tested period. The value of odor intensity for combinations W2/F1, W2/F2 and W2/F3 was between the odor intensity values of separately tested floor materials. No positive impact was noticed for the OSB boards with an addition of PVC wallpaper (W2/F4) in the odor intensity assessment. The recommended odor intensity was not reached by any material combinations. Comparing the results obtained by odor intensity scale and acceptability scale, it was found that they correspond to each other. 3.2. Chemical assessment Chemical assessment for the individual flooring materials (F1, F2, F3, F4) and their combinations with wall/ceiling coverings (W1, W2) is shown within Figs. 6–9. 3.2.1. Individual materials chemical assessment Concerning individual materials, the highest TVOC value was found for OSB board flooring. The results of chemical assessments for OSB
Fig. 2. Sensory assessment (F1, W1, W2).
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Fig. 3. Sensory assessment (F2, W1, W2).
boards correspond to results of sensory assessments. TVOC concentration from wall/ceiling construction materials was pretty much higher for tested painted gypsum boards than for PVC wallpaper. The TVOC concentrations for painted gypsum boards were relatively high (534 μg/m3 ); the highest value was estimated only for OSB boards (1080 μg/m3 ). But the odor intensity and air acceptability for painted gypsum boards were acceptable. On the other hand the worst acceptability was caused by PVC wallpaper but the lowest TVOC concentration (168 μg/m3) was found. The value of TVOC concentration for high density fiber board laminate flooring is slightly above comfort level. The TVOC value was pretty under 200 μg/m 3 comfort value (Molhave) for PA carpet covering (121 μg/m3).
3.3. Material combination chemical effect The studied effect of material combinations to chemical assessment expressed by TVOC concentration was markedly positive for PVC flooring and painted gypsum board (W1/F1) with regard to both individual tested materials. The F1 TVOC concentration (532 μg/m3) was very similar to the W1 TVOC concentration (534 μg/m3). The decrease for the W1/F1 combination was nearly 50% even if the final value was slightly above comfort value. The decrease for the W2/F1 combination was only 30%. Following these results the PVC flooring is more effective combined with painted gypsum board walls than with PVC wallpapers (Fig. 6). It is better to combine the laminate flooring of high density fiber boards with wallpapers. Also for the combination with painted
gypsum boards (W1/F2) the nearly 400 μg/m3 value was obtained but the laminate flooring combination with wallpaper (W2/F2) is more preferable (Fig. 7). Similar results for PA carpeting combinations were confirmed (Fig. 8). The markedly negative effect was found for combination of OSB boards and painted gypsum boards (W1/F4) with regard to both individual tested materials as well as for the combination of OSB and wallpaper (W2/F4). As seen in Fig. 9 both values for combinations are quite high.
4. Discussion The selection of the materials in Slovakia is strongly based on the intuitive assumption that they will reduce exposure of occupants to potentially dangerous or harmful chemicals. This is the first paper that examines the concentration exposure of VOC and odor perceiving in indoor air of interior materials typically used in Slovakia. By all studied material combinations the TVOC concentration decrease was obtained only with regard to one of the tested materials. The emissions from tested surface materials and their combinations are considered important as no acceptability was found. The most important indoor odor sources were the determined materials based on PVC and OSB boards. Several tested materials and their combinations were slightly unacceptable and by some testing were almost clearly unacceptable. Basically the majority of the tested materials combinations resulted to an improvement in sensory and chemical environmental ratings. No specified reason to impact material interaction effects on perceived air quality was found.
Fig. 4. Sensory assessment (F3, W1, W2).
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5
Fig. 5. Sensory assessment (F4, W1, W2).
1400
Table 2 Sensory assessment of tested indoor materials. AA (−1;+1)
OI (0;5)
PN [%]
F1 F2 F3 F4 W1 W2
−0.39 −0.38 −0.32 −0.62 −0.17 −0.73
2.15 2.21 1.79 3.21 1.77 3.19
87 84 65 96 65 98
TVOC [µg/m3]
1200 Indoor material
1000 800 600 400 200 0 F3
1400
W2
W1/F3
W2/F3
Fig. 8. Chemical analysis (F3, W1, W2).
1200 1000 1400 800 1200
600 400 200 0 F1
W1
W2
W1/F1
W2/F1
TVOC [µg/m3]
TVOC [µg/m3]
W1
1000 800 600 400
Fig. 6. Chemical analysis (F1, W1, W2).
200 0 F4
1400
W2
W1/F4
W2/F4
Fig. 9. Chemical analysis (F4, W1, W2).
1200
TVOC [µg/m3]
W1
1000
Table 3 Sensory assessments vs. chemical analysis.
800
Combination
600
PGB
400 200
PVCW
0 F2
W1
W2
W1/F2
Fig. 7. Chemical analysis (F2, W1, W2).
W2/F2
PVC HDF PA OSB PVC HDF PA OSB
CTVOC [μg/m3]
Air acceptability
Odor intensity
✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓
✓ ✓ ✓ ✗ ✓ ✓ ✓ ✗
✓ ✓ ✓ ✗ ✓ ✓ ✓ ✗
✓, positive effect; ✗, no effect.
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The strongest effect of material interaction was found by combinations with painted gypsum boards. No positive effect on perceived air quality was found for the tested material combinations with OSB boards (Table 3). The necessity of parallel chemical and sensory analyses of indoor air quality was confirmed. On the basis of the results, it is possible to assume that the human nose is much more sensitive than chemical testing procedures. Both methods used in parallel, chemical testing and sensory measurements, are equally useful for perceived air quality assessment and providing important information about the acceptability of building materials for indoor use. The purpose of sensory assessment is to consider influence of indoor air quality to wellbeing.
5. Conclusion The interior surface material emissions and odors were investigated in a glass test chamber. The aimed material combinations impact on air quality was reported and the positive effects of selected material combinations were recognized. The significant impact of indoor surface materials on perceived air quality as well as generally the positive interaction effect was confirmed. Both, methods used in parallel, chemical testing and sensory measurements, are equally useful for perceived air quality assessment and providing important information about the acceptability of indoor materials. The main purpose of sensory assessment is to consider and mainly respect the influence of indoor air quality to human wellbeing. In order to guarantee acceptable indoor air quality the identification of all important indoor odor sources is required. The measure of indoor air pollution decreasing is the effective material control. Demand control material selection seems to be the most important approach in building design with respect to perceived indoor air quality and green building concept.
Acknowledgments The authors are grateful to the Slovak Grant Agency for supporting. References [1] O. Bjorseth, Sorption behavior of volatile organic compounds on material surfaces— the influence of combinations of compounds and materials compared to sorption of single compounds on single materials, Environ. Int. 25 (1999) 17–27. [2] M. Bortoli, S. Kephalopoulos, S. Kirchner, H. Schauenburg, H. Vissers, State-of the-art in the measurement of volatile organic compounds emitted from building products: results of European interlaboratory comparison, Indoor Air 9 (1999) 103–116. [3] F. Haghighat, L. Bellis, Material emission rates: literature review, and the impact of indoor air temperature and relative humidity, Build. Environ. 33 (1998) 261–277. [4] W. Horn, O. Wilke, K. Wiegner, Results of RR-VOC-BAM_2009, Final Report. BAM, Federal Institute for Materials Research and Testing, Berlin, 2010. [5] C. Howard-Reed, S.J. Nabinger, Developing a standard reference material for VOC emissions testing, Proceedings of the Indoor Environmental Quality: Problems, Research and Solutions Conference (113–119), Research Triangle Park NC: EPA/AWMA, 2006. [6] C.C. Lin, K.P. Yu, P. Zhao, G.W. Lee, Evaluation of impact factors on VOC emissions and concentrations from wooden flooring based on chamber tests, Build. Environ. 44 (2009) 525–533. [7] J. Popa, F. Haghighat, Characterization of the sink effect of VOCs on building materials, with specific emphasis on painted surfaces, Proceeding of Indoor Air 2002, Concordia University, Montreal, 2002, pp. 558–563. [8] W. Sakr, et al., The impact of building materials and their combinations on perceived air quality, Proceedings of Healthy Buildings 2000, Concordia University, Canada, Danish Building Research institute, Denmark, 2000, p. 79. [9] W. Sakr, et al., Sorptive interactions among building materials and their resultant impact on perceived indoor air quality, Proceedings of Indoor Air 2005, Beijing, 2005, pp. 1–5. [10] I. Senitkova, T. Tomcik, Interior materials impact to indoor air quality, Adv. Sci. Lett. 19 (3) (2013) 955–959. [11] Y.P. Zhang, X.X. Luo, X.K. Wang, K. Qian, R.Y. Zhao, Influence of temperature on formaldehyde emission parameters of dry building materials, Atmos. Environ. 41 (2007) 3203–3216. [12] B. Yeganeh, F. Haghighat, L. Gunarsen, A. Afshari, H. Knudsen, Evaluation of building materials individually and in combination using odour threshold, Indoor Build. Environ. 15 (2006) 583–593. [13] P. Wolkoff, Impact of air velocity, temperature, humidity, and air on long-term VOC emissions from building products, Atmos. Environ. 32 (1998) 2659–2668.
