## 5 Wood-Based Panel Emissions
### Wood Panels Bonded without Adhesive
#### 5.2.1 VOC Emissions from Heat-Treated Softwoods  
Scots pine has been extensively studied. In particular, [PERSON] et al. [11] compared emissions from simply dried pine with those from pine heat-treated (at 230 \({}^{\circ}\)C with steam for 24 h). They identified 41 volatile organic compounds, but only 14 were common to both untreated and treated pine. They showed that the main VOCs in untreated pine are terpen (notably \(\alpha\)-pinene and \(\alpha\)-terpinene) and aldehydes (mainly hexanal), accounting for 71% and 25% of total emissions, respectively. Alcohols, ketones, and aromatic hydrocarbons were also detected in small quantities. In the case of treated pine, the main compounds emitted were aldehydes, accounting for 35% of emissions (notably furfural), and carboxylic \begin{table}
\begin{tabular}{c c c} \hline \hline
**Type of Wood Panel** & **VOCs Identified in Emissions** & **References** \\ \hline \multirow{4}{*}{OSB} & Formaldehyde, hexanal, and \(\alpha\)-pinene, among others & [135] \\ \cline{2-3}  & Formaldehyde, acetaldehyde, propanal, pentanal, hexanal, benzaldehyde, & [134] \\ \cline{2-3}  & furfural, acrolein & \\ \cline{2-3}  & Formaldehyde * & [133] \\ \hline \multirow{2}{*}{Plywood} & Formaldehyde * & [114; 134; 136; 137] \\ \cline{2-3}  & Formaldehyde acetaldehyde, propanal, hexanal, pentanal & [134] \\ \hline \multicolumn{3}{c}{*: Compound specifically researched.} \\ \end{tabular}
\end{table} 
Table 6: _Cont._acids and their esters, accounting for 30% (mainly acetic acid). Ketone emissions also increased compared to untreated pine (from 1% before treatment to 16% following heat treatment). On the other hand, terpene emissions dropped sharply with heat treatment, accounting for just 10% of total emissions. It is important to note that terpene composition changed with heat treatment, as the authors identified 13 terpen in emissions from untreated pine, compared with 5 in emissions from treated pine. [PERSON] and [PERSON] (2014) also studied VOC emissions from pine (_Pinus sylvestris_) in connection with Thermwood heat treatment at 180 \({}^{\circ}\)C or 230 \({}^{\circ}\)C. TVOC emissions decreased after heat treatment (1486 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\) for untreated wood versus 828 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\) and 235 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\) for pine treated at 180 \({}^{\circ}\)C and 230 \({}^{\circ}\)C, respectively). Emissions from untreated pine were mainly terpen: \(\upalpha\)-pinene (174 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\)), camphene (232 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\)), and limonene (191 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\)). Hexanal was also emitted by untreated pine (43 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\)). Terpene and hexanal emissions decreased with heat treatment temperature (between 180 \({}^{\circ}\)C and 230 \({}^{\circ}\)C): from 312 to 24 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\) for \(\upalpha\)-pinene, from 32 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\) to below the detection limit for camphene, from 153 to 1 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\) for limonene, and from 8 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\) to below the detection limit for hexanal. Conversely, acetic acid emissions increased with heat treatment temperature: 5 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\) for untreated pine, 78 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\) for pine treated at 180 \({}^{\circ}\)C, and 110 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\) for pine treated at 230 \({}^{\circ}\)C. Furfural was emitted in greater quantities at 180 \({}^{\circ}\)C (29 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\)) than at 230 \({}^{\circ}\)C (10 \(\upmu\)g m\({}^{-2}\) h\({}^{-1}\)). [PERSON] et al. (2015) also studied VOC emissions from Scots pine (sapwood or heartwood) but subjected to two types of treatment: heat treatment and vacuum heat treatment, at temperatures of 180 \({}^{\circ}\)C or 200 \({}^{\circ}\)C. VOC emissions from untreated pine were measured for comparison with those from heat treatment.