## 4 Analysis Method for Source Appointment and Contribution
### NP Method for Source Contribution  
Recently, a source appointment method using 1-NP and pyrene as emission markers (NP-method) has been developed. Here, the order of combustion temperature of the three major sources of NPAH emissions is as follows: biomass combustion (500-600 \({}^{\circ}\)C) \(<\) coal combustion (1100-1200 \({}^{\circ}\)C) \(<\) vehicles (2700-3000 \({}^{\circ}\)C) [16]. The NP method is based on the assumption that ratios of NPAHs to parent PAHs increase with the increase in combustion temperature. This method is powerful, because it can analyze contribution ratios of mixed sources for not only PAHs and NPAHs but also combustion particulates. In the NP-method, particulate matter (PM) in the air is divided into combustion-derived particulate matter (P\({}_{c}\)) and non-combustion-derived particulate matter (P\({}_{o}\)). Both \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Compounds** & **Sample** & **Analysis Method** & **LOD and Recovery** & **Ref.** \\ \hline
14 NPAHs (2-Naip; 2-NBp; 5-NaAcc; 2-NF; 9-NAnt; 9-NNP; 2+3-NFR; 1-NP; 2-7-DNF; 6-NC; 1-3-16, 18-DNFPs; 5-NaPhJ, 16 PAHs, 9 PAHQs, 5-PAOHHs. & Sediment. & GC-MS/MS, Capillary columns; DB-SMS column, 30 m \(\times\) 0.25 mm & \\
1-SP; 2-7-DNF; 6-NCP; 1-3, 16-, 18-DNFPs; 6-NaPhJ, 16 PAHs, 9 PAHQs, 5-PAOHHs. & Sediment. & id. NICI-SRM (NPAHs), El-SIM (OPAHs), El-SIM (OPAHs), 1C-MS/MS (OPAHs). & LODs of NPAHs: 0.002–0.067 ng g\({}^{-1}\). & [59] \\  & & & (PAHs), El-SIM (OPAHs), & \\  & & & LC-MS/MS (OOHTAHs). & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: \(Cont.\)the formation of nitrogen oxides and the subsequent formation of NPAHs from parent PAHs depend on combustion temperature. Therefore, the concentration ratio of [NPAH]/[PAH] increases with increasing combustion temperature. Based on the difference in combustion temperature difference of the major sources described above, P\({}_{\rm c}\) can be further divided into two particulates emitted from high-temperature combustion (P\({}_{\rm h}\)) and from low-temperature combustion (P\({}_{\rm I}\)). When the proportion of P\({}_{\rm h}\) in P\({}_{\rm c}\) is \(x\) (0 \(<\)\(x\) \(<\) 1) and the proportion of P\({}_{\rm c}\) in P is \(y\) (0 \(<\)\(y\) \(<\) 1) in the air, following Equations (1)-(3) can be written as:  
\[[\rm 1\text{-}NP]=[\rm 1\text{-}NP_{\rm h}][P_{\rm c}]x+[\rm 1\text{-}NP_{\rm h }][P_{\rm c}](1-x) \tag{1}\]  
\[[\rm Pyr]=[\rm Pyr_{\rm h}][P_{\rm c}]x+[\rm Pyr_{\rm I}][P_{\rm c}](1-x) \tag{2}\]  
\[y=[P_{\rm c}]/([P_{\rm c}]+[P_{\rm o}]) \tag{3}\]  
NPAHs and PAHs were determined in particulates emitted from different combustion processes. Among them, 1-NP and Pyr are common NPAHs and PAHs in particulates, respectively. In the NP-method, concentration ratios of 1-NP and Pyr in particulates emitted from vehicles ([1-NP\({}_{\rm h}\)]/[\(\rm Pyr_{\rm h}\)] = 0.425) and coal combustion ([1-NP\({}_{\rm I}\)]/[\(\rm Pyr_{\rm I}\)] = 0.0013) are used for P\({}_{\rm h}\) and P\({}_{\rm I}\), respectively ([PERSON] et al., 2020; 2021). By introducing these values into Equations (i) to (iii), x, y and [P\({}_{\rm c}\)] can be obtained [70]. Moreover, the NP can calculate contributions of high- and low-temperature combustions to 1-NP and Pyr. When the proportion of 1-NP\({}_{\rm h}\) in 1-NP (= 1-NP\({}_{\rm h}\) + 1-NP\({}_{\rm I}\)) in the air be \(a\) (0 \(<\)\(a\) \(<\) 1) and the proportion of \(\rm Pyr_{\rm h}\) in Pyr (= \(\rm Pyr_{\rm h}\) + \(\rm Pyr_{\rm I}\)) in the air be \(b\) (0 \(<\) \(b\) \(<\) 1), the following equations are obtained:  
\[[\rm 1\text{-}NP_{\rm h}]=[\rm 1\text{-}NP]a\text{ and }[\rm 1\text{-}NP_{\rm I}]=[\rm 1 \text{-}NP](1-a) \tag{4}\]  
\[[\rm Pyr_{\rm h}]=[\rm Pyr]b\text{ and }[\rm Pyr_{\rm I}]=[\rm Pyr]\text{ }(1-b) \tag{5}\]  
Dividing Equation (4) by Equation (5), following equations are obtained for the concentration ratio of 1-NP to Pyr for each source.