An umbrella review of public health interventions to mitigate air pollution and improve health outcomes in high-income countries.

INTRODUCTION: Air pollution remains a major contributor to morbidity and mortality in high income countries (HICs), particularly in urban environments where traffic and other combustion sources dominate emissions. This umbrella review aimed to synthesise evidence on interventions to mitigate air pollution and improve health outcomes in HICs, including equity considerations. CONTENT: Eight systematic reviews were included, covering city- and transport-level policies, individual and household exposure-reduction strategies and modelling of emission-reduction and net-zero pathways. Transport interventions showed consistent cardiovascular benefits and reductions in traffic injuries. Portable air cleaners reduced indoor PM2.5 and were associated with modest improvements in blood pressure. Modelling studies projected substantial health co-benefits, including a median mortality reduction of approximately 1.5 %. SUMMARY: Structural policy interventions provided the most consistent population health benefits while individual and household-level interventions offered complementary effects. Modelling evidence supported the potential health gains of large-scale mitigation and net-zero strategies. OUTLOOK: Equity impacts were rarely assessed and findings were inconsistent. Greater consideration of equity in the design and evaluation of future air-pollution interventions is needed.