Public Transport Subsidization and Air Pollution: Evidence from the 9-Euro-Ticket in Germany

We study the short-term effects of the 9-Euro-Ticket, a major German public transport subsidization program, on particulate matter (PM). Using hourly PM readings from pollution monitoring stations throughout Germany, provided by the German Federal Environmental Agency, we find declines in PM₁₀ and PM₂.₅ at core traffic stations, displaying differential effects of -0.44 µg/m³ and -0.41 µg/m³ relative to less frequented locations, which corresponds to approximately 2.8 % and 8.5 % of the current limit guidelines that the WHO suggests to mitigate adverse effects on human health. Pollution reductions materialize in regions with above-average public-transportation accessibility, are most pronounced during peak travel times on weekdays and in regions with above-average population density and larger car fleets, suggesting reductions in car usage sign responsible for our findings. This notion is supported by plausibility tests that employ NO₂ and SO₂ as outcomes. These insights into consequences of ticket-fare subsidization for air quality and potential causal pathways are of relevance for policymakers involved in transportation (infrastructure) planning to accommodate such directly incentivizing policy tools in the future.