Uncovering the Global Burden and Future Trajectories of Nanomagnetite Particle Emissions from Biomass Power Plants

Biomass power plants (BPPs) are expanding rapidly, yet the most toxicologically potent nanoscale fraction of its particulate emissions remains poorly quantified. Here, in vitro assays demonstrate that nanomagnetite particles (NMPs) constitute a disproportionately toxic subfraction of fine particles: despite contributing only 2.3% of particle mass, NMPs account for 59% of cytotoxicity. On this basis, we quantify NMP emissions from BPPs by integrating measured NMP concentrations with data-augmented machine-learning models and unit-level activities. The resulting global inventory shows strong spatial disparities, with national average concentrations ranging from 150 to over 2000 mg/kg and total global emissions reaching 230 (92-530) t in 2024. Asia contributes 45% of global emissions, followed by South America (26%) and Europe (20%), driven by differences in feedstock composition, installed capacity, and dust removal performance. Scenario projections further indicate that deployment of advanced dust removal technologies under a carbon-neutrality-oriented pathway could reduce global NMP emissions to 76 t by 2050. These results reveal a previously unrecognized source of nanoscale pollution and provide a quantitative framework for integrating NMPs into future bioenergy and air-quality strategies.