## 4 Why and How to Measure Volatile Organic Compound Emissions from a Material?  
Volatile organic compounds (VOCs) have many definitions, depending on the organizations that publish them and the regulations to which they apply. The World Health Organization (WHO) [87] characterizes VOCs as compounds with boiling points between 50-100 \({}^{\circ}\)C and 240-260 \({}^{\circ}\)C. Based on this definition, many compounds are included in VOCs, with diverse compositions and structures: aliphatic hydrocarbons (alkanes, alkenes and alkynes), alicyclic hydrocarbons (cyclic hydrocarbons derived from the aliphatic series), aromatic hydrocarbons (including some polycyclic aromatic hydrocarbons), and substituted hydrocarbons (halogens, alcohols, aldehydes, ketones, ethers and esters, acids, amines, amides, and nitriles).  
Although there is no universal definition of VOCs, their impacts on human health and on the environment are acknowledged worldwide [88; 89]. First, VOCs affect human health with direct and indirect effects. VOCs can be toxic substances at various levels, with some VOCs even classified as carcinogenic, mutagenic, and reprotoxic (CMR), such as formaldehyde or benzene. Furthermore, since VOCs are precursors of ozone in the air, they can lead to an overproduction of ozone, a gas that is itself toxic, causing various symptoms in humans depending on the level of exposure: coughing, shortness of breath, nasal, eye and throat irritation, among others. Ozone can also have harmful effects on vegetation, altering plant resistance to pathogens and accelerating the degradation of certain materials. Moreover, the overproduction of ozone generates an additional greenhouse effect. It should be noted that VOCs can generally be of biogenic or anthropogenic origin. Table 3 presents some VOCs commonly studied.  
\begin{table}
\begin{tabular}{c c c} \hline
**Wood Species** & **Pretreatment** & **References** \\ \hline _Abias alba_ and _Pinus insignis_ & Steam explosion & [80] \\ Oil palm trunk & / & [70] \\ Oil palm trunk & / & [72] \\ _Picea mariana_ bark & Refining & [81] \\ Oil palm trunk & / & [82] \\ _Pinus radiata_ & Fenton reaction & [83] \\ Aspen & Steam stabilization & [84] \\ _Picea abies_ and _Fagus sylatica_ & Fenton reaction & [85] \\ _Papulus eunamevicana_ & / & [86] \\ \hline \end{tabular} \(/\): no pretreatment.  
\end{table}
Table 2: Wood-based binderless boards.  
\begin{table}
\begin{tabular}{c c c c c c} \hline  & **Compound** & **CAS** & **MW (g mol\({}^{-1}\))** & **Bp (\({}^{\circ}\)C) [90; 91]** & **CMR Classification [14]** \\ \hline C\({}_{1}\) & Formaldehyde & 50-00-0 & 30 & –19 & **Carc. 2** \\ \hline C\({}_{2}\) & Acetaldehyde & 75-07-0 & 44 & 21 & **Carc. 2** \\ Acetic acid & 64-19-7 & 60 & 118 & **Carc. 3** \\ \hline \multirow{3}{*}{C\({}_{3}\)} & Acetone & 67-64-1 & 58 & 56 & **Carc. 3** \\  & Acrolein & 107-02-8 & 56 & 52 & **Carc. 3** \\  & Propanal & 123-38-6 & 58 & 48 & **Carc. 3** \\  & Tetrachlororeflyene & 127-18-4 & 166 & 121 & **Carc. 2** \\ \hline C\({}_{4}\) & Butanal & 204-646-6 & 72 & 75 & **Carc. 3** \\  & 2-Butanal & 4170-30-3 & 70 & 102 & **Muta. 2** \\ \hline C\({}_{5}\) & Furfural & 98-01-1 & 96 & 162 & **Carc. 2** \\ \hline \multirow{3}{*}{C\({}_{6}\)} & Benzene & 71-43-2 & 78 & 80 & **Carc.1**, Muta. 2** \\  & 2-Butoxyethanol & 111-76-2 & 118 & 170 & **Carc. 3** \\  & 1,4-Dichlorobenzene & 106-46-7 & 147 & 173 & **Carc. 2** \\  & _n_-Hexane & 110-54-3 & 86 & 69 & **Repr. 2** \\ \hline \multirow{3}{*}{C\({}_{7}\)} & Benzaldehyde & 100-52-7 & 106 & 179 & **Carc. 3** \\  & Toluene & 108-88-3 & 92 & 111 & **Repr. 2** \\ \hline \end{tabular}
\end{table}
Table 3: Some VOCs and some of their characteristics.