## 3 Results and Discussion
### Primary and Secondary VOC Emissions
#### 3.2.3 Comparison with the Emission Data from the NRC Database
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Sources** & \multicolumn{4}{c}{**This Study**} & \multicolumn{4}{c}{**NRC Database**} \\ \hline Materials & OSB & Plywood & Pine & Carpet & OSB & Plywood & Pine & Carpet \\ \hline \multirow{2}{*}{Chemicals} & \multicolumn{4}{c}{Emission rates with no intentional ozone exposure, \(\upmu\)g\(\cdot\)m\({}^{-2}\)\(\cdot\)h\({}^{-1}\)} \\  & \multicolumn{4}{c}{(Emission rates with exposure to ozone at concentrations around 100 ppm, \(\upmu\)g\(\cdot\)m\({}^{-2}\)\(\cdot\)h\({}^{-1}\))} \\  & 111.6 & 58.0 & 30.3 & 0 & 5.6–10.4 & 0 & 0 & 1.5–2.2 \\  & (120.4) & (43.6) & (34.6) & (0) & 5.6–10.4 & 0 & 0 & 1.5–2.2 \\ \hline \multirow{2}{*}{Acetaldehyde} & 0 & 0 & 0 & 0 & 0 & 34.3–66.1 & 0 & 0 & 0.7–3.7 \\  & (1.2) & (1.8) & (0) & (0) & 2.1–98.4 & 2.2–5.1 & 1.1–1.3 & 0.2–41.3 \\ \hline \multirow{2}{*}{Hexanal} & 0 & 0 & 0 & 0 & 0 & 10.9–927.8 & 7.9–18.2 & 3.2 & 0.1–0.5 \\  & (0) & (0) & (0) & (0) & (0) & 0.1–0.9 & 0–0.3 & 0.2 & 0–0.2 \\ \hline \multirow{2}{*}{Toluene} & 9.9 & 2.6 & 18.0 & 15.0 & & & & \\  & (0) & (1.1) & (35.6) & (35.6) & 0.2–83.9 & 0.4–0.5 & 0.5–0.7 & 0–1.7 \\ \hline \multirow{2}{*}{Ethylbenzene} & 0 & 0 & 0 & 0 & 0 & 0 & 0.1–7 & 0–0.1 & 0.1 & 0–31.5 \\  & (3.7) & (8.6) & (0) & (9.1) & 0–1.7 & 0–0.1 & 0 & 0 & 0–1.7 \\ \hline \multirow{2}{*}{Styrene} & 0 & 0 & 0 & 0 & 0 & 0 & 0.1–0.9 & 0–0.1 & 0 & 0–1.7 \\  & (0) & (9.6) & (0) & (0) & (0) & 0.1–0.9 & 0–0.3 & 0.2 & 0–0.2 \\ \hline \multirow{2}{*}{Toluene} & 9.9 & 2.6 & 18.0 & 15.0 & & & & & \\  & (0) & (1.1) & (35.6) & (35.6) & 0.2–83.9 & 0.4–0.5 & 0.5–0.7 & 0–1.7 \\ \hline \multirow{2}{*}{Ethylbenzene} & 0 & 0 & 0 & 0 & 0 & 0 & 0.1–7 & 0–0.1 & 0.1 & 0–31.5 \\  & (3.7) & (8.6) & (0) & (9.1) & 0–1.7 & 0–0.1 & 0 & 0–1.7 \\ \hline \multirow{2}{*}{Styrene} & 0 & 0 & 0 & 0 & 0 & 0 & 0.1–0.9 & 0–0.1 & 0 & 0–1.7 \\  & (0) & (9.6) & (0) & (0) & (0) & 0.1–0.9 & 0–0.3 & 0.2 & 0–0.2 \\ \hline \multirow{2}{*}{Toluene} & 9.9 & 2.6 & 18.0 & 15.0 & & & & & \\  & (0) & (1.1) & (35.6) & (35.6) & 0.2–83.9 & 0.4–0.5 & 0.5–0.7 & 0–1.7 \\ \hline \multirow{2}{*}{Ethylbenzene} & 0 & 0 & 0 & 0 & 0 & 0 & 0.1–7 & 0–0.1 & 0.1 & 0–31.5 \\  & (3.7) & (8.6) & (0) & (9.1) & 0–1.7 & 0–0.1 & 0 & 0–31.5 \\ \hline \multirow{2}{*}{Styrene} & 0 & 0 & 0 & 0 & 0 & 0 & 0.1–0.1 & 0 & 0 & 0–1.7 \\  & (0) & (9.6) & (0) & (0) & (0) & 0.1–0.9 & 0–0.3 & 0.2 & 0–0.2 \\ \hline \multirow{2}{*}{Toluene} & 9.9 & 2.6 & 18.0 & 15.0 & & & & & \\  & (0) & (1.1) & (35.6) & (35.6) & 0.2–83.9 & 0.4–0.5 & 0.5–0.7 & 0–1.7 \\ \hline \multirow{2}{*}{Ethylbenzene} & 0 & 0 & 0 & 0 & 0 & 0 & 0.1–7 & 0–0.1 & 0.1 & 0–31.5 \\  & (3.7) & (8.6) & (0) & (9.1) & 0–1.7 & 0–0.1 & 0 & 0–31.5 \\ \hline \multirow{2}{*}{Styrene} & 0 & 0 & 0 & 0 & 0 & 0 & 0.1–0.1 & 0 & 0 & 0–1.7 \\  & (0) & (9.6) & (0) & (0) & (0) & 0.1–0.9 & 0–0.3 & 0.2 & 0–0.2 \\ \hline \multirow{2}{*}{Toluene} & 9.9 & 2.6 & 18.0 & 15.0 & & & & & \\  & (0) & (1.1) & (35.6) & (35.6) & 0.2–83.9 & 0.4–0.5 & 0.5–0.7 & 0–1.7 \\ \hline \multirow{2}{*}{Toluene} & 0 & 0 & 0 & 0 & 0 & 0.1–0.7 & 0–0.1 & 0–0.1 & 0–31.5 \\  & (3.7) & (8.6) & (0) & (9.1) & 0–1.7 & 0–0.1 & 0–0.1 & 0–31.5 \\ \hline \multirow{2}{*}{Toluene} & 0 & 0 & 0 & 0 & 0 & 0 & 0.1–0.1 & 0 & 0–0.1 \\  & (0) & (9.6) & (0) & (0) & (0) & 0.1–0.9 & 0–0.3 & 0–0.3 & 0–0.2 & 0–0.2 \\ \hline \multirow{2}{*}{Toluene} & 9.9 & 2.6 & 18.0 & 15.0 & & & & & & \\  & (0) & (1.1) & (35.6) & (35.6) & 0.2–83 Overall, the following observations can be made based on Table 7. First, among the listed chemicals, formaldehyde is very important for wood-based materials in China, though it may be less important in the NRC database. The emission rates of toluene were also high based on the measurements in this study. Although few specimens of OSBs in the NRC database exhibited high emission rates of toluene, in most cases, the emission rates of toluene were low.