Polycyclic aromatic hydrocarbons (PAHs) are oxidized to hydroxy-PAHs (OHPAHs), quinoid-PAHs [PAH quinones (PAHQs)], and nitro-PAHs (NPAHs). Quantitative analysis is essential for understanding their emissions, environmental behaviors, exposures, and health risks. Although NPAHs exhibit far stronger mutagenicity compared with PAHs, fewer studies on NPAHs exist owing to the previous lack of highly sensitive analytical methods. Atmospheric concentrations follow the order PAHs > PAHQs > OHPAHs > NPAHs. However, highly sensitive methods for analyzing NPAHs have now been developed, increasing the number of studies focusing on atmospheric NPAHs. Additionally, source analysis methods have emerged, with NPAHs and PAHs as critical monitoring targets. This chapter covers sampling and cleanup procedures for PAHs and NPAHs in atmospheric samples, as well as instrumental analysis techniques, including high-performance liquid chromatography–fluorescence detection/chemiluminescence detection and gas chromatography–mass spectrometry.