Assessing the impact of air pollution on anemia: a comprehensive review and meta-analysis

Introduction Air pollution and household fuel use may impair hematologic health through inflammation and oxidative stress. We synthesized evidence on associations of ambient/household air pollution with anemia risk and erythrocyte indices.Methods We searched PubMed, Embase, and Web of Science (inception–27 September 2025). Two reviewers independently screened and extracted data, and assessed risk of bias using Joanna Briggs Institute checklists. Random-effects meta-analyses pooled risk ratios (RRs) per 10 µg/m3 for particulate matter with aerodynamic diameter ≤10 µm (PM10), ≤2.5 µm (PM2.5), and nitrogen dioxide (NO2), and by household fuel type.Results Thirty-six studies were included. Each 10 µg/m3 increase in PM2.5 and NO2 was associated with higher anemia risk (RR 1.200, 95% CI 1.041–1.384, I2 98.2%; RR 1.127, 95% CI 1.025–1.241, I2 98.0%). Solid and biomass fuel increased anemia risk (RR 1.143, 95% CI 1.027–1.274, I2 82.9%; RR 1.271, 95% CI 1.050–1.539, I2 91.7%). PM10 was associated with lower hemoglobin (0.074 g/dL, 95% CI −0.124 to −0.023, I2 90.7%). Effects were generally stronger in males and in low- and middle-income countries.Conclusions Ambient and household air pollution are associated with increased anemia risk and reductions in hemoglobin; high heterogeneity and observational designs limit causal inference.