This work shows the potential of iodine to increase the sulphuric acid- and dimethylamine-driven nucleation rates through coupled chemical cycles.

Iodic acid is a well-known driver for marine new particle formation (NPF), showing high efficiency in nucleation. Despite its recent detection over land and rapid global increase, its role in continental NPF and the resulting current and future atmospheric impacts remain unknown. Here, we present molecular-level evidence that iodic acid can substantially facilitate particle formation (1.5 to 50 times by 2060) by its synergistic nucleation with the typical land-based pollutants, sulfuric acid and amine, thus effectively capturing the observed inland NPF events in China. These findings highlight the significance of considering iodine-involved nucleation in accurately modelling continental particle formation and the resulting aerosol-related climatic impacts, particularly in the future with declining sulfur and increasing iodine emissions. The results are published in PNAS: https://www.pnas.org/doi/abs/10.1073/pnas.2404595121