Volatile organic compounds in wooden buildings - Marko Hyttinen / Department of Environmental and Biological Science Research group for Indoor ...
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Volatile organic compounds in wooden buildings
Marko Hyttinen / Department of Environmental and Biological Science
Research group for Indoor Environment and Occupational Health
UEF // University of Eastern Finland 12.4.2021
marko.hyttinen @ uef.fi
Introduction •In the European Union (EU) 8-10% of single-family buildings have a wooden frame and regional variations ranging from above 80 % in Nordic countries to near zero in many southern European countries (Hurmekoski, 2017) •Wood has been used as an interior material in all kinds of buildings. •In addition, the many furniture are made from wooden materials (e.g. Artek and Alvar Aalto products) UEF // University of Eastern Finland
How wood affects indoors
• Wood as a construction and interior material affects a building’s
indoor environment in several ways:
– Wood emits chemical compounds (aldehydes, carboxylic acids,
terpenes…)
– Buffers the moisture content of indoor air (hygroscopic material)
– Influences the acoustical environment
– Influences bacterial environment
• Wood has been used in interior settings, such as panelled walls and
ceilings, wooden floorings, furniture, and solid-wood structures that
have wooden interior surface (e.g., timber).
References (Risholm-Sundman, et al., 1998; Li, et al., 2012; Asdrubali, et al., 2017; Vainio-Kaila, 2017).
UEF // University of Eastern Finland
Odor / Irritation •Most people find odor from wood pleasant •Pleasant odor can be caused the same VOCs which can in some cases be irritative (e.g. aldehydes, ”carboxylic acids”, terpenes) •Terpenes have a pleasant odor (at low concentration) •Odor treshold values
Volatile organic compounds (VOCs)
• The European Union defines a VOC as "any organic compound having
an initial boiling point less than or equal to 250 °C.”
• Volatile organic compounds (VOCs) have been measured from the
indoor air already since the 80’s. (e.g. aldehydes, alcohols, aliphatic
and aromatic hydrocarbons, carboxylic acids, glycols, esters, ethers,
siloxanes, and terpenes) (Shah and Singh, 1988; De Bortoli et al., 1989; Mølhave., 1991; Knöppel
and Wolkoff, 1992; Brown et al., 1994; Wolkoff 1998).
• The method based on gas chromatography with thermodesorption
injection is well established and routinely used in-house inspections
and material emission testing.
UEF // University of Eastern Finland
VOCs can be categorizes into classes by their boiling point (WHO
1989)
Category description Acronym Boiling-point range, E.g. compounds
C
Very volatile (gaseous) organic VVOC 380
with particulate matter or
particulate organic matter
UEF // University of Eastern Finland 12.4.2021
Total Concentration of Volatile Organic Compounds (TVOC) • Total Concentration of Volatile Organic Compounds (sum of VOCs in size range between hexane to hexadecane (C6-C16). Can be detected analytically with TD-GC-MS of GC-FID when using a non-polar column. (ISO-16000-6) • Measured by toluene standard, which underestimates concentrations of polar compounds. • Ease to measure. Gives data about overall behavior of VOCs in indoor environment. Used when testing material emissions. • No cause-effect relationship exists between TVOC concentrations and health effects (Wolkoff 1995, Andersson et al. 1997, ECA, 1997, Wolkoff and Nielsen 2001). → use of TVOC not relevant from a health point of view UEF // University of Eastern Finland
Composition of wood • Wood consists primarily of cellulose, hemicellulose and lignin, extractives (E.g. Softwood species include 33–42% cellulose, 22–40% hemicellulose, 27–32% lignin, and 2–3.5% extractives) (Sjöström, 1993) • The composition and content of these compounds vary between tree species and growing locations, and additionally, variation within species and inside an individual tree can be substantial (Kirkeskov, et al., 2009; Steckel, et al., 2011). • The major VOC emissions occurs during wood’s drying process, when the most volatile compounds evaporate (Granström, 2005). Generally, emissions decrease over time (Kirkeskov, et al., 2009), but the emissions from freshly dried timber can be considerable (Steckel, et al., 2011) UEF // University of Eastern Finland
VOC emissions from softwood • Softwoods are usually rich in extracts and, therefore, can release substantial amounts of VOCs, mainly terpenes and aldehydes (Risholm-Sundman, et al., 1998; Manninen, et al., 2002). • Softwoods contain mostly mono- sesqui- and diterpenes (Granström, 2005), and approximately 80% of VOC emissions from fresh softwood are monoterpenes (Hyttinen, et al., 2010) • The main terpenes found in emission from pines and spruces are monoterpenes α-pinene, β-pinene, limonene and 3-carene • Terpenes originate from the wood resin (Granström, 2005; Widhalm, et al., 2016), while aldehydes are secondary emissions formed from oxidation of unsaturated fatty acids (Risholm-Sundman, et al., 1998; Steckel, et al., 2011; Widhalm, et al., 2016). UEF // University of Eastern Finland
VOC emissions from hardwoods • Emissions from hardwoods provide a more versatile range of carbonyl compounds and alcohols (Risholm-Sundman, et al., 1998). • Aldehydes, especially hexanal and pentanal, are found in most hardwoods’ emissions (Risholm-Sundman, et al., 1998). • Some species, such as oak, beech and cherry, produce high emission of acetic acid, which is formed from the hydrolysis of acetyl groups in hemicellulose (Risholm-Sundman, et al., 1998). UEF // University of Eastern Finland
Factors affecting VOC emissions indoors • Age of the material/product • Ventilation (air exchange rate) • Temperature and relative humidity • Air flow at surface • Material thickness, density, surface characteristics • Material influence on sink effect (adsorption/desorption) • High surface to volume ratios (S/V) →surface reactions are potentially very important. (Weschler et al. 2001) • E.g. Parquet compared to carpet UEF // University of Eastern Finland 12.4.2021
TVOC during and after the construction of the wooden frame house (µg/m3).
Wooden frame
Indoors oak parquet,
ceramic tile, mdf-ceiling
panel, gypsum board
UEF // University of Eastern Finland 12.4.2021VOCs during and after the construction of the wooden frame house (µg/m3). Day when house ready: -13 -12 -11 0 6 20 62 85 235 Total (including some VVOC) 4350 4890 5070 5630 3140 1130 630 290 120 TVOC (C6-C16) 4150 4680 4830 5270 3290 1090 590 260 105 1-Propanol, 2-methyl- 614 393 373 237 107 11 5 2 2 1-Butanol 244 279 229 202 219 13 6 5 2 2-Butanone, oxime 255 134 157 49 15 nd nd nd nd 2-Propanone, oxime 82 48 61 11 2 nd nd nd nd Hexanal 119 229 192 195 80 24 13 7 5 2-Heptenal, (E)- 7 15 11 9 nd 2 nd nd nd Toluene 53 106 115 34 14 4 2 1 nd Xylenes 274 196 139 80 32 10 3 2 nd Acetic acid, butyl ester 94 133 75 56 21 4 13 1 nd Butanoic acid, butyl ester 72 81 101 166 139 32 27 18 nd Methane, diethoxy- 193 138 120 124 91 14 10 7 nd Cyclopentasiloxane, decamethyl- 23 37 46 75 47 70 24 38 1 Alpha-Pinene 626 958 229 1180 630 245 184 65 48 Delta-carene 319 640 726 609 290 107 77 22 19 Limonene 59 81 106 258 74 134 17 5 6 UEF // University of Eastern Finland
6 timber-frame (TF) and 6 solid wood (SF),
Wooden flooring (oak)
First sample at a late state of construction
VOC-levels high level in the beginning
SW: terpenes 44%, aldehydes 29%, organic
acids 13%, others 14%)
TF: 30/34/28%
Concrete-built reference (aldehydes 41%,
“others” 35%, terpenes 17%)
Emissions decreased to an average level
within 6-8 months
VOCs decreased faster in houses with
mechanical ventilation vs. manual
ventilation
Residents very satisfied with IAQ all the
time ☺
Fürhapper et al. Living Conditions in Timber
UEF // University of Eastern Finland Houses: Emission Trends and Indoor Air12.4.2021
Quality,
2020Heat-treated vs. air-dried timber • Heat-treated wood is a popular decoration material and is used in floor, wall, and ceiling materials and in furniture. • Heat-treatment darkens the wood and helps to sustain better UV radiation and rot fungi • Heat treated process (3 stages): temperature rise first (100-130°C), heat- treatment (185-215°C for 1-4hr), and cooling and humidification. • Next two examples about VOC-emissions of Air-dried and Heat-treated wooden board materials (Scots-Pine, European-Aspen) 12.4.2021
VOC Emissions Between Air-dried and Heat-treated Scots Pine Wood
Hyttinen et al. 2010 Atmos Environ.
Main VOCs from air-
dried wood sample:
Alpha-pinene, delta-
carene, hexanal, and
other terpenes
Main VOCs (heat-
treated): Acetic acid,
furfural, hexanal, delta-
carene
UEF // University of Eastern Finland 12.4.2021TVOC emissions from air-dried and heat-treated
European Aspen wood samples
Main VOCs from air-dried wood sample:
Hexanal, pentanal, acetic acid, 1-pentanol,
1-penten-3-oli
Main VOCs (heat-treated): Acetic acid,
furfural
12.4.2021Summary
• New building materials (e.g. fresh timber) emits high levels of VOCs
• VOC emissions decreases relatively fast (time frame within 6 months)
• Terpenes, aldehydes, and carboxylic acids are the most common VOCs
from wooden houses/materials
– Emissions vary between tree species and growing locations, how timber
has been processed, maintained etc..
• Parameters which affect emissions
– Aging of the material
– Temperature
– Relative humidity
• Residents satisfied with indoor air quality (timber-frame and solid-
wood houses)
UEF // University of Eastern FinlandReferences • Fürhapper Christina, Habla Elisabeth, Stratev Daniel, Weigl Martin, Dobianer Karl, 2020, Living Conditions in Timber Houses: Emission Trends and Indoor Air Quality, Frontiers in Built Environment • Granström, K., 2005. Emissions of volatile organic compounds from wood. [Dissertation], Karlstad, Sweden: Karlstad University. • Hurmekoski, E., 2017. How can wood construction reduce environmental degradation?, Joensuu, Finland: European Forest Institute • Hyttinen, M., Masalin-Weijo, M., Kalliokoski, P. & Pasanen, P., 2010. Comparison of VOC emissions between air-dried and heat treated Norway spruce (Picea abies), Scotch pine (Pinus sylvesteris) and European aspen (Populus tremula) wood. Atmospheric Environment, Volume 44, pp. 5028-5033 • Kasanen, J. et al., 1999. Evaluation of sensory irritation of 3-carene and turpentine, and accaptable levels of monoterpenes in occupational and indoor environment. Journal of Toxicology and Environmental Health, Volume 56, Part A, pp. 89-114 • Kirkeskov, V. et al., 2009. Health evaluation of volatile organic compound (VOC) emission from exotic wood products. Indoor air, 19(2), pp. 45-57 • Risholm-Sundman, M., Lundgren, M., Vestin, E. & Herder, P., 1998. Emissions of acetic acid and other volatile organic compounds from different species of solid wood. Holz als Roh und Werkstott, Volume 56, pp. 125-129. • Steckel, V., Welling, J. & Ohlmeyer, M., 2011. Product emissions of volatile organic compounds from convection dried Norway spruce (Picea abies (L.) H. Karst.) timber. International Wood Products Journal, 2(2), pp. 75-80 • Vainio-Kaila, T. et al., 2017a. Antibacterial effects of wood structural components and extractives from Pinus sylvestris and Picea abies on methicillin-resistant Staphylococcus aureus and Escherichia coli O157:H7. BioResources, 12(4), pp. 7601-7614 • Widhalm, B., Ters, T., Srebotnik, E. & Rieder-Gradinger, C., 2016. Reduction of aldehydes and terpenes within pine wood by microbial activity. Holzforschung, 70(9), pp. 895-900 UEF // University of Eastern Finland
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