Inhalable cigarette-burning particles: Size-resolved chemical composition and mixing state.

This study analyzed the size-resolved chemical compositions of cigarette-burning particles (CBPs). CBPs in the size range of 0.2-2.0 μm were characterized using a single particle mass spectrometer (SPAMS). CBPs were found to contain polycyclic aromatic hydrocarbons (PAHs), organonitrate, vinylpyridine, indene, guaiacol, methylindane, and metals such as Fe, Cr, Mn, and Cu. Fresh CBPs showed a single modal size distribution which peaked at 0.40 μm. CBPs in the size range of 0.5-0.1 μm contained more biomass burning markers (K, KCl, and levoglucosan), sulfate, naphthalene, and methylindane than CBPs in the size range of 0.2-0.5 μm. Nicotine is favorable to uptake on large particles (>0.5 μm). Among all particles, 57% contained PAHs. Heavy metals Fe, Mn, Cr, and Cu had mixing ratios of 0.06, 0.57, 0.26, and 0.34 respectively; nicotine and guaiacol had mixing ratios of 0.26 and 0.27; and vinylpyridine, indene, and methylindane had mixing ratios of 0.54, 0.55, and 0.65 respectively. Four particle types were resolved: cigarette-burning biomass burning (CB-BB, 50.3%), CB-BB-Metals (49.3%), CB-Nicotine (0.3%), and CB-Aged (0.1%). These results improve the scientific understanding of CBPs and provide useful references for smoking exposure studies that consider the size-resolved chemical compositions and mixing states of particle-phase components. The result can also benefit the study of exposure to secondhand smoking.