Airborne particulate matter (PM) contains hazardous polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) emitted from various combustion sources. The lack of effective methods for identifying these sources has impeded research in atmospheric pollution and public health. This chapter introduces a novel source analysis method, the NP method, for identifying combustion-derived atmospheric particulates (Pc), PAHs, and NPAHs. The method bases on the temperature dependence of nitrogen oxide (NOx) formation during organic material combustion and the subsequent conversion of PAHs to NPAHs. Using 1-nitropyrene (1-NP) and pyrene as key markers, the NP method classifies combustion sources into high-temperature (vehicles) and low-temperature (coal/biomass) categories. Formulas are derived for the fraction of Pc in PM [y (0 < y < 1)], with Pc further divided into high-temperature (Ph) and low-temperature (Pl) combustion fractions [Pc values of x (0 < x < 1) and (1 − x), respectively]. Additionally, the fractions of high-temperature combustion-derived 1-NP and pyrene in atmospheric 1-NP and pyrene are calculated as a (0 < a < 1) and b (0 < b < 1), respectively. This chapter details the theory, performance, and applications of the NP method, which surpasses conventional source appointment techniques.