## 2 Materials and Methods
### Testing Procedures  
#### 2.3.1 Ozone Deposition Velocities  
The tests on ozone deposition velocity and VOC emissions were performed separately. To conduct ozone deposition on materials, the following methods and procedures were employed. First, two ten-time series of experiments--one using 100 ppb of ozone and another using 300 ppb--were conducted on the empty chamber to obtain the two average deposition velocities of ozone on the chamber wall. Clean air was pumped through the channel connected to the chamber into an ozone generator (2B 306, 2B Technology, Inc., Boulder, CO, USA, the flowrates were 1.0-1.3 L\(\cdot\)min\({}^{-1}\) during the experiments). Then, air was introduced into the chamber with a constant concentration of ozone. The ozone concentration was measured and recorded by an ozone analyzer (2B 106-L/205, 2B Technology, Inc., Boulder, CO, USA, with a flowrate ranging from 0.8 to 1.1 L\(\cdot\)min\({}^{-1}\) when sampling) at a 1 min interval using one of the outlet ports. As shown in Equation (1), a mass balance model of ozone concentration in the chamber was used to determine the ozone deposition on the chamber surfaces:  
\[V\frac{\mathrm{d}y_{\mathrm{ozone}}}{\mathrm{d}t}=NV(y_{\mathrm{ozone,in}}-y_{ \mathrm{ozone}})-36v_{\mathrm{d,s}}A_{\mathrm{d,s}}y_{\mathrm{ozone}}-36v_{ \mathrm{d,w}}(A_{\mathrm{d,w}}-A_{\mathrm{d,s}})y_{\mathrm{ozone}}, \tag{1}\]  
where \(V\) is the volume of the chamber, m\({}^{3}\); \(y_{\mathrm{ozone}}\) is the indoor ozone concentration in the chamber (or in a room), \(\mu\)g\(\cdot\)m\({}^{-3}\); \(N\) is the air change rate, h\({}^{-1}\); \(y_{\mathrm{ozone,in}}\) is the ozone concentration in the supplied air, \(\mu\)g\(\cdot\)m\({}^{-3}\); \(v_{\mathrm{d,s}}\) and \(v_{\mathrm{d,w}}\) are the area-averaged ozone deposition velocity on the testing specimen and the chamber wall, respectively, cm\(\cdot\)s\({}^{-1}\); and \(A_{\mathrm{d,s}}\) and \(A_{\mathrm{d,w}}\) are the exposed area for ozone deposition on the specimen and chamber wall, respectively, in m\({}^{2}\). The zone deposition velocity on the material specimen under a steady state can be calculated via Equation (2):  
\[v_{\mathrm{d,s}}=\frac{NV}{A_{\mathrm{d,s}}}\bigg{(}\frac{y_{\mathrm{ozone,in }}}{y_{\mathrm{ozone}}}-1\bigg{)}-v_{\mathrm{d,w}}\bigg{(}\frac{A_{\mathrm{d,w }}}{A_{\mathrm{d,s}}}-1\bigg{)}, \tag{2}\]  
and \(v_{\mathrm{d,w}}\) can be determined by Equation (3) when no sample is placed in the chamber:  
\[v_{\mathrm{d,w}}=\frac{NV}{A_{\mathrm{d,w}}}\bigg{(}\frac{y_{\mathrm{ozone,in }}}{y_{\mathrm{ozone}}}-1\bigg{)}. \tag{3}\]  
We tested the ozone deposition in an empty chamber by purging the ozone at two different concentrations ten times. In this way, \(v_{\mathrm{d,w}}\)s were both determined to be \(1.25\times 10^{-3}\pm 0.28\times 10^{-3}\) cm\(\cdot\)s\({}^{-1}\), which is similar to the results reported in [39]. After determining \(v_{\mathrm{d,w}}\) using the empty-chamber tests, \(v_{\mathrm{d,s}}\) was determined by conducting ozone deposition tests on different materials. Each time, one specimen from each of the materials was placed in the chamber, and the steady-state \(v_{\mathrm{d,s}}\) value was determined using Equation (2) along with the procedure described in this section. Since each test lasted for approximately 1-6 h, at least two tests were repeated on the same specimen, and two specimens were prepared for all the wood-based materials. A summary of the testing procedure for ozone deposition velocities is given in Table 3.