Health Risks and Economic Burden of PM2.5 and Its Constituents on Online Purchases of Antibiotics and Antivirals: A Nationwide Study in China

Abstract While previous studies have shown that fine particulate matter (PM2.5) has been associated with respiratory tract infections caused by bacterial and viral pathogens based on mortality and morbidity data, its impact on subclinical manifestations and related partial self-treatment behaviors remains poorly understood. This nationwide study investigates the health risks and economic burden associated with daily PM2.5 and its major constituents in relation to online purchases of antibiotics in 344 cities and antivirals in 299 cities across China. We analyzed the city-specific effects of PM2.5 and its major constituents on online purchase data from China’s Meituan platform (2022–2024) using a time-stratified case-crossover design with distributed lag linear models. City-level estimates were pooled by random-effect meta-analysis. We subsequently quantified attributable risks and economic burdens due to PM2.5 exposure. The study included 111,408,946 antibiotic and 21,395,469 antiviral online purchases. An interquartile range (IQR) increase in PM2.5 total mass at lag 0–7 days was associated with a 1.04% [95% confidence interval (CI): 1.03–1.05%] increase in antibiotic purchases and a 1.14% (95% CI: 1.10–1.17%) increase in antiviral purchases at the national level. Among PM2.5 constituents, pooled relative risks (RRs) showed similar magnitude, with only marginal variations. Geographic and seasonal heterogeneity was observed, with stronger associations in southern areas and winter. Central and Eastern China accounted for most attributable health and economic burdens. PM2.5 exposure significantly increases both health risks and economic costs associated with online purchases of antibiotics and antivirals in China. These findings provide critical evidence for policymakers, healthcare providers, and researchers to optimize environmental health policies and medical resource allocation strategies.