Atmospheric emissions of Ti-containing nanoparticles from industrial activities in China†

Inhalation of exogenous Ti-containing nanoparticles (NPs) can have adverse effects on human health. However, few studies have considered industrial emissions, which contribute significantly to atmospheric levels of Ti-containing NPs. In this study, we quantified Ti-containing NP emissions in samples of fine particulate matter (particle sizes: 40–120 nm) collected from 132 full-scale industrial plants. Coal-fired power plants emitted the highest particle number concentrations of Ti-containing NPs (1.7 × 10¹⁰ particles per g), followed by solid waste incineration (7.7 × 10⁹ particles per g) and blast furnace pig iron steelmaking (5.5 × 10⁹ particles per g); coking plants and iron-ore sintering were also significant contributors to Ti-containing NPs emissions. Collectively, these five sources accounted for 99.9% of the annual atmospheric emissions of Ti-containing NPs from 13 industrial sectors in China (total ≈ 9.8 × 10²² particles). Moreover, these industrial emissions increased the atmospheric concentration of Ti-containing NPs by 1.7 × 10⁷ particles per m³, therefore leading to the general population's lifetime average daily dose (LADD) of inhaled Ti-containing NPs being 2.4 × 10⁶ particles per day per kg. The findings presented herein highlight the importance of assessing NP emissions and advancing sustainable global industrial development.