Stratospheric aerosol injection (SAI) is a proposed climate intervention that could potentially reduce future global warming, but its broader environmental and public health implications are yet to be thoroughly explored. Here, we assess changes in mortality attributable to fine particulate matter (PM_2.5) and ozone (O₃) using three large ensembles of fully coupled CESM2-WACCM6 simulations from the ARISE-SAI-1.5, ARISE-SAI-1.0 and SSP2-4.5 scenarios. In the ARISE-SAI-1.5 scenario, maintaining temperatures at 1.5 degrees above preindustrial levels through SAI results in a modest reduction in pollution-related mortality during 2060–2069 relative to SSP2-4.5, driven by a 1.26 % decrease in ozone-related deaths and a 0.86 % increase in PM_2.5-related deaths. PM_2.5 mortality changes exhibit almost no sensitivity to injected sulfate amounts, with the most variability driven by precipitation-mediated changes in non-sulfate PM_2.5 species (e.g., dust and secondary organic aerosols), whereas ozone-related mortality are primarily driven by surface cooling and hemispheric asymmetries in stratospheric-tropospheric exchange and ozone transport. Overall, SAI impacts on pollution-related mortality are modest, regionally heterogeneous, and much smaller in magnitude compared to improvements expected from near-term air quality policies. Our finding that mortality impacts do not directly scale with SO₂ injection rates underscores the nonlinear and complex nature of atmospheric responses to SAI. Significant differences across ensemble members further emphasize the role of internal variability and the need for ensemble-based analysis when evaluating potential health implications of climate intervention strategies.