## 4 Discussion  
The present study demonstrated that exposure to PAHs, even at low levels, was associated with the onset of nasal symptoms. After adjustment, we found that Flt, Pyr and BkF were significantly associated with nasal symptoms. To the best of our knowledge, this is one of only a few longitudinal studies on the relationships between PAHs and nasal symptoms. The results obtained suggest that specific PAHs cause nasal symptoms. Although exposure to PAHs has been shown to increase the risk of respiratory or cardiovascular diseases among adults [27; 28; 29; 30], limited information is currently available on the relationships between PAHs and rhinitis. One study found that prenatal exposure to PAHs increased the risk of nasal symptoms and cough among children during their \begin{table}
\begin{tabular}{c c c c c c c} \hline \multicolumn{2}{c}{**Parameter**} & \multicolumn{2}{c}{**Std.**} & \multicolumn{2}{c}{**95\% Wald Confidence Interval**} & \multicolumn{1}{c}{\(p\)} \\ \hline
**Pollutant** & **Lag File** & **B** & **Error** & **Lower** & **Upper** & \\ \hline \multirow{6}{*}{BaP} & 0 & \(-6.259\) & \(3.695\) & \(-13.501\) & \(0.982\) & \(0.090\) \\ \cline{2-7}  & 1 & \(3.514\) & \(3.283\) & \(-2.921\) & \(9.948\) & \(0.285\) \\ \cline{2-7}  & 2 & \(0.420\) & \(3.449\) & \(-6.340\) & \(7.179\) & \(0.903\) \\ \cline{2-7}  & 3 & \(3.364\) & \(3.925\) & \(-4.329\) & \(11.057\) & \(0.391\) \\ \cline{2-7}  & 4 & \(-5.315\) & \(4.193\) & \(-13.533\) & \(2.903\) & \(0.205\) \\ \cline{2-7}  & 5 & \(4.446\) & \(4.211\) & \(-3.807\) & \(12.699\) & \(0.291\) \\ \hline \multirow{6}{*}{DahA} & 0 & \(22.150\) & \(18.589\) & \(-14.283\) & \(58.583\) & \(0.233\) \\ \cline{2-7}  & 1 & \(10.541\) & \(18.519\) & \(-25.755\) & \(46.836\) & \(0.569\) \\ \cline{2-7}  & 2 & \(-7.699\) & \(25.640\) & \(-57.952\) & \(42.554\) & \(0.764\) \\ \cline{2-7}  & 3 & \(9.469\) & \(27.837\) & \(-45.092\) & \(64.029\) & \(0.734\) \\ \cline{2-7}  & 4 & \(-27.462\) & \(28.258\) & \(-82.847\) & \(27.923\) & \(0.331\) \\ \cline{2-7}  & 5 & \(32.113\) & \(22.907\) & \(-12.784\) & \(77.009\) & \(0.161\) \\ \hline \multirow{6}{*}{BghiP} & 0 & \(-3.927\) & \(2.156\) & \(-8.152\) & \(0.299\) & \(0.069\) \\ \cline{2-7}  & 1 & \(2.062\) & \(1.781\) & \(-1.428\) & \(5.553\) & \(0.247\) \\ \cline{2-7}  & 2 & \(2.369\) & \(2.226\) & \(-1.995\) & \(6.733\) & \(0.287\) \\ \cline{2-7}  & 3 & \(0.159\) & \(2.377\) & \(-4.500\) & \(4.818\) & \(0.947\) \\ \cline{2-7}  & 4 & \(-0.202\) & \(2.525\) & \(-5.151\) & \(4.747\) & \(0.936\) \\ \cline{2-7}  & 5 & \(2.025\) & \(2.639\) & \(-3.148\) & \(7.198\) & \(0.443\) \\ \hline \multirow{6}{*}{IcdP} & 0 & \(-6.646\) & \(2.688\) & \(-11.914\) & \(-1.378\) & \(0.013\)\({}^{*}\) \\ \cline{2-7}  & 1 & \(3.255\) & \(2.385\) & \(-1.420\) & \(7.929\) & \(0.172\) \\ \cline{2-7}  & 2 & \(3.105\) & \(3.074\) & \(-2.920\) & \(9.131\) & \(0.312\) \\ \cline{2-7}  & 3 & \(0.010\) & \(3.250\) & \(-6.359\) & \(6.380\) & \(0.997\) \\ \cline{2-7}  & 4 & \(0.507\) & \(3.162\) & \(-5.690\) & \(6.704\) & \(0.873\) \\ \cline{2-7}  & 5 & \(1.325\) & \(3.513\) & \(-5.559\) & \(8.210\) & \(0.706\) \\ \hline \end{tabular} Symbol \({}^{*}\) in bold are statistically significant (\(p<0.05\)).  
\end{table} 
Table 2: _Cont._first year of life [31]. Difficulties are also associated with finding studies that examined the relationships between nasal symptoms and PAHs. We only found studies on the effects of specific PAHs on the respiratory system. A cohort study in Wuhan and Zhuhai reported correlations between lung function and exposure to Flt and Pyr in adults [negatively correlated with forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1)] [32]. [PERSON] et al. showed that after exposure to PAHs, an increased risk of cough was found among chronic cough patients in both lag2 and lag6 [33; 34]. These findings suggest that PAHs affect the human respiratory system, which is consistent with the present results.