Anemia is associated with long-term exposure to PM2.5 and its components: a large population-based study in Southwest China.

Background: Anemia is linked to PM_2.5 (particulate matter with aerodynamic diameters of ⩽2.5 μm) exposure, which can increase the risk of various negative health outcomes. It remains unclear which PM_2.5 components are associated with anemia and the respective contribution of each component to this association.

Objective: This study aimed at investigating the association between PM_2.5 and anemia in the general population and to identify the most critical PM_2.5 toxic components in this association.

Design: Cross-sectional study.

Methods: Our study involved a large cohort of 73,511 individuals aged 30-79 from China's multi-ethnic population. We employed satellite observations and the chemical transport model (GEOS-Chem)to estimate the long-term exposure to PM_2.5 and its components. Anemia was defined, according to WHO guidelines, as Hb levels below 130 g/L for men and below 120 g/L for women. Through logistic regression, we investigated the association between PM_2.5 components and anemia. By utilizing weighted quantile sum (WQS) analysis, we identified key components and gained insights into their combined impact on anemia. Overall, our study sheds light on the relationship between PM_2.5 exposure, its constituents, and the risk of anemia in a large cohort.

Results: PM_2.5 and three components, nitrate (NIT), organic matter (OM), and soil particles (SOIL), were associated with anemia. Per-standard deviation increase in the 3-year average concentrations of PM_2.5 [odds ratio (OR): 1.14, 95% confidence interval (CI): 1.01, 1.28], NIT (1.20, 1.06, 1.35), OM (1.17, 1.04, 1.32), and SOIL (1.22, 1.11, 1.33) were associated with higher odds of anemia. In WQS regression analysis, the WQS index was associated with anemia (OR: 1.29, 95% CI: 1.13, 1.47). SOIL has the highest weight among all PM_2.5 components.

Conclusions: Long-term exposure to PM_2.5 and its constituents is associated with anemia. Moreover, SOIL might be the most critical component of the relationship between PM_2.5 and anemia. Our research increases the evidence of the association between PM_2.5 and anemia in the general population, and targeted emission control measures should be taken into consideration to mitigate the adverse effects of PM_2.5-related anemia.