Unequal toxic effects of size-segregated single particles emitted from typical industrial plants, vehicles, and road dust

The health risks of particulate matters (PMs) associated with their chemical components and sizes have attracted increasing attention. However, the toxic effect of critical toxic components in size-segregated PMs from specific emission source remains unclear. We present the toxicity of size-segregated elements in PMs via integrating toxic analysis and online single-particle measurements of real-world industrial plants, vehicles, and road dust. The number fractions of elemental carbon (EC)- and Fe-containing particles were 5-11 and 3-12 folds greater than those of other metal-containing particles, respectively. A unimodal distribution with the peak at 0.4 µm was observed for the toxic metals emitted from industrial plants and road dust, while the distribution was relatively flat for vehicles. When integrating the abundance with toxicity of metals, especially Mn, Cu, V, and Fe, the peak for PM toxicity occurred at 0.4 µm for road dust, 0.4-0.7 µm for industrial plants, and 0.8 µm for vehicle-emitted PM. The inhalation risk in the alveolar region increased for these source-emitted PMs due to the efficient deposition of toxic PMs within 0.4-0.8 µm. These results reveal the complex coupling of health risks and size distributions of PMs, and further highlight that the health-oriented control of air pollution should consider PM₁.