Short-term lagged exposure to ambient air pollutants and hospitalization costs among AMI patients: health-economic evidence from a low-pollution Chinese city with DRG/DIP standardized medical payment

Background Ambient air pollution poses substantial cardiovascular health and economic burdens worldwide, yet existing evidence largely focuses on high-pollution regions and clinical endpoints such as incidence or mortality. Few studies have quantified air pollution-attributable hospitalization costs for acute myocardial infarction (AMI), especially under low air quality conditions. Combined with China's Diagnosis-Related Groups (DRG) / Diagnosis-Intervention Packet (DIP) case-mix medical payment reform, hospitalization expenses can serve as a reliable proxy reflecting AMI disease severity and healthcare resource consumption, providing a unique health-economic perspective for environmental public health policy-making. Methods A single-center retrospective cohort study was conducted including 3,650 percutaneous coronary intervention (PCI)-treated AMI patients admitted to Jiangmen Central Hospital (2018–2024), a subtropical city with year-round air pollutant concentrations meeting China Grade II standards. Lag-stratified Gamma generalized linear models with log link were applied to evaluate associations between pre-admission 0–6 day exposure to six criteria pollutants (PM 2.5 , PM 10 , SO 2 , NO 2 , CO, O 3 ) and AMI hospitalization costs. All single-pollutant models were fully adjusted for demographics, comorbidities, seasons, weekdays, and non-linear meteorological confounders. Benjamini–Hochberg false discovery rate (FDR) correction was used to control multiple testing bias. A sensitivity analysis restricted to 1,590 never-smoking patients was performed. Results Short-term exposure to SO 2 , PM 2.5 , PM 10 , NO 2 , and CO was significantly associated with elevated AMI medical expenditures, while O 3 showed no overall significant correlation. Per natural log-unit elevation, SO 2 generated the largest cost increase (average 2.40%, ~729 CNY) with consistent adverse effects across all lag days; particulate pollutants PM 2.5 and PM 10 exhibited delayed peak risks at lag 4–5 days. In never-smokers, O 3 triggered significant cost rises at lag 3 and lag 5, indicating non-smokers as vulnerable subgroups susceptible to ozone toxicity. Multicollinearity diagnostics validated the rationality of single-pollutant modeling. Conclusions Even low-level ambient air pollution compliant with current national standards increases the economic burden of AMI treatment, with SO 2 showing the strongest association. Smoking modifies cardiovascular cost-related effects of ozone. This population-level health-economic evidence supports stricter air quality regulations, and the integration of ambient exposure indicators into AMI risk stratification and public health resource allocation under the DRG/DIP payment system.