# Indoor Air Pollution Increases the Risk of Lung Cancer
## 3 Results
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Characteristics**} & **Lung Adenocarcinoma** & **Nonmalignant Controls** & \multirow{2}{*}{_p_**-Value**} \\  & **(_n = 39_)** & **(_n = 40_)** & \\ \hline Age (years), mean (SD) & 66.0 (12.5) & 74.5 (15.1) & 0.01 \({}^{*}\) \\ Male, no. (\%) & 48 (60.8) & 31 (39.2) & 0.55 \\ \hline Clinical stage & & \\ \hline I (\%) & 1 (2.6) & & \\ II (\%) & 0 (0.0) & & \\ III (\%) & 4 (10.5) & & \\ IV (\%) & 33 (86.8) & & \\ \hline EGFR & & \\ \hline Positive (\%) & 18 (43.4) & & \\ Negative (\%) & 20 (52.6) & & \\ \hline Individual factors & & \\ \hline Cigarette smoking & & & \\ \hline Smoking status & & 0.56 \\ Nonsmoker, no. (\%) & 27 (69.2) & 31 (79.5) & \\ Current smoker, no. (\%) & 1 (2.6) & 1 (2.6) & \\ Former smoker, no. (\%) & 11 (28.2) & 7 (18.0) & \\ Second-hand smoke (\%) \({}^{1}\) & 0 (0.0) & 0 (0.0) & \\ Pack-years, mean (SD) & 11.2 (22.5) & 7.4 (18.2) & 0.42 \\ \hline Occupational factor & & & \\ \hline High risk occupation \textgreater{} 10 years (\%) & 3 (7.7) & 1 (2.5) & 0.29 \\ \hline Hereditary factor & & & \\ \hline Family history of lung cancer (\%) \({}^{2}\) & 11 (30.6) & 0 (0.0) & 0.00 \({}^{*}\) \\ \hline Environmental factors & & & \\ \hline Lived near main street (\textless{}500 m) (\%) & 36 (92.3) & 37 (94.9) & 0.64 \\ Distance between home and main street, m (SD) & 364.5 (280.9) & 335.1 (358.3) & 0.71 \\ Lived near factory (\%) & 2 (5.1) & 0 (0.0) & 0.15 \\ Habitual cooking at home (\%) \({}^{1}\) & 16 (42.1) & 8 (21.1) & 0.048 \({}^{*}\) \\ Habitual indoor incense burning (\%) \({}^{1}\) & 18 (47.4) & 13 (34.2) & 0.24 \\ Habitual use of essential oil (\%) \({}^{1}\) & 2 (5.3) & 1.0 \\ \hline \hline \end{tabular} \({}^{1}\) More than three days a week for more than six months; \({}^{2}\) First-degree relative ever had lung cancer; \({}^{*}\) p-value \textless{} 0.05.  
\end{table} 
Table 2: Indoor air pollutants and the risk of lung adenocarcinoma. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Risk Factor**} & \multicolumn{3}{c}{**Include Current Smoker**} & \multicolumn{3}{c}{**Exclude Current Smoker**} \\ \cline{2-7}  & **Crude OR** & \(p\) & **Adjusted OR**\({}^{1}\) & \(p\) & **Crude OR** & \(p\) & **Adjusted OR**\({}^{1}\) & \(p\) \\ \hline
**All** & 2.73 & & 2.16 & & 2.76 & & 2.22 \\ Habitual cooking at home & (0.99–7.50) & 0.05 & (0.75–6.25) & 0.15 & (1.00–7.64) & 0.05 & (0.77–6.44) & 0.14 \\ Habitual incense burning & 1.73 & & 2.68 & & 1.97 & & 3.05 \\ (0.69–4.36) & (0.69–4.36) & 0.24 & (0.95–0.98) & 0.06 & (0.77–5.07) & 0.16 & (1.06–8.84) & 0.04 \({}^{*}\) \\
**Female** & 5.50 & & 5.39 & & 5.50 & 5.39 & \\ Habitual cooking at home & (1.15–26.4) & 0.03 & (1.11–26.2) & 0.04 \({}^{*}\) & (1.15–26.41) & 0.03 \({}^{*}\) & (1.11–26.20) & 0.04 \({}^{*}\) \\ Habitual incense burning & 5.78 & & 0.04 \({}^{*}\) & 6.01 & & 5.78 & 0.04 \({}^{*}\) & 6.01 & 0.03 \({}^{*}\) \\
**Male** & (1.12–29.85) & & (1.14–31.66) & & (1.12–29.85) & 0.04 \({}^{*}\) & (1.14–31.66) & 0.03 \({}^{*}\) \\ Habitual cooking at home & 2.11 & & 1.51 & & 2.12 & & 1.54 & 0.64 \\ (0.46–9.73) & (0.46–9.73) & 0.34 & (0.24–9.43) & 0.66 & (0.46–9.84) & 0.34 & (0.25–9.46) & 0.64 \\ Habitual incense burning & 0.86 & & 2.20 & & 1.03 & & 2.26 & 2.26 \\ (0.27–2.76) & 0.80 & (0.48–10.07) & & (0.31–3.39) & 0.97 & (0.56–12.90) & 0.22 \\ \hline \hline \end{tabular} \({}^{1}\) Adjusted for age. \({}^{*}\) p-value \textless{} 0.05.  
\end{table} 
Table 1: Demographic characteristics of the study subjects. Figure 4: Receiver operating characteristic curves for lung cancer predicted by environmental exposure histories and exposure biomarkers in pleural fluid. We included the prediction variables of environmental exposure histories (lived near the main street, distance to the main street, cigarette smoking, incense burning, essential oil) and exposure biomarkers (PAHs and BTEX in pleural fluid) and used four machine learning algorithms to establish a prediction algorithm.