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.