Addressing gaps in integrated air quality-vegetation-health impact analysis: A call for broader implementation and long-term strategies in industrial cities

This letter acknowledges the valuable contribution of the authors' study, which investigates the associations between long-term air pollution exposure and plasma metabolites in two sub-cohorts of the Rotterdam Study. The use of advanced metabolomics techniques and land use regression models for exposure assessment is praised for strengthening the study's methodology. The identification of enriched metabolic pathways, such as steroid hormone biosynthesis and pyrimidine metabolism, provides key insights into how air pollution affects biological systems. However, the letter highlights the limitation of the study's cross-sectional design, which hinders causal inference, and suggests that longitudinal studies would offer more definitive conclusions. The mention of "unannotated metabolites" is noted as an intriguing yet underexplored aspect, and further discussion of confounding factors such as diet and socioeconomic status is encouraged. Overall, the letter offers constructive feedback while recognizing the study's important contribution to the field.