Air Pollution, Anemia and Nutrition: A Scoping Review of Research Gaps in the Role of Nutrients in PM2.5-Related Anemia

Anemia, a major global public health issue, has been increasingly linked to air pollution. Growing evidence suggests that fine particulate matter (PM2.5) exposure is associated with reduced hemoglobin concentrations and increased anemia risk, potentially through pathways involving oxidative stress, inflammation, and disrupted hematopoiesis. This review examines whether nutrients or supplements, such as iron, vitamins B, C, and D, and folate, and the social context have a protective effect and can modify PM2.5-related anemia. Following JBI guidelines, we systematically searched databases such as PubMed and Web of Science to screen 3450 studies. Across diverse geographic settings, the included studies consistently reported the following: (a) an inverse association between PM2.5 exposure and anemia-related outcomes, including lower hemoglobin concentrations and altered hematologic indicators, and an increased anemia risk; (b) an adequate nutritional status, particularly higher intake or levels of iron, folate, and antioxidant vitamins, may attenuate the adverse hematologic effects of PM2.5 exposure, but evidence remains limited; and (c) adverse social conditions such as lower income and lower education can amplify vulnerability to PM2.5-related anemia, but this evidence also remains limited. Further research is needed to better understand how nutritional factors and the social environment modify susceptibility to PM2.5-related anemia.