Invisible Threat: How Airborne Pollution Fuels Antimicrobial Resistance in the EU

Recent scientific research suggests that the environment represents an important pathway for the spread of antimicrobial resistance (AMR). This paper is the first to provide causal estimates of the impact of fine particulate matter (PM2.5) on AMR diffusion. I focus on EU countries and the period 2002 to 2019. To pin down causal effects, I use an instrumental variable approach that exploits temperature inversions as a source of exogenous shocks to air pollution. I find that a 1% increase in PM2.5 leads to about a 0.7% increase in average antibiotic resistance, but there is significant heterogeneity across pathogen-antibiotic combinations in their responsiveness to changes in pollution. I then separately estimate the direct impact of pollution on resistance, as well as the impact of an indirect channel via antibiotic consumption. When antibiotic use is accounted for, the direct influence of air pollution on AMR remains sizable and significant. Finally, I provide a counterfactual analysis assessing the impact of alternative air pollution control policies on resistance and compare their effectiveness vis-à-vis interventions aimed at reducing antibiotic use in humans. Findings imply that air pollution policies can be fruitfully leveraged in the fight against AMR propagation.