Variable Short-Term Air Quality Impacts of New York City’s Congestion Pricing Policy

On January 5, 2025, New York City implemented the Central Business District Tolling Program (CBDTP): a congestion pricing policy aimed at reducing traffic and improving air quality within the Manhattan central business district. We evaluate the short-term effects of the policy on local air pollution, using both ground-based and satellite observations. Using New York City Community Air Survey (NYCCAS) street-level real-time PM _2.5 monitoring sites, we compare mean PM _2.5 concentrations during the first six months of CBDTP implementation to the same months in 2024, finding statistically significant decreases in PM _2.5 following the CBDTP. To assess causality, we then employ a difference-in-differences (DiD) regression approach to analyze PM _2.5 concentration changes. When temporal trends are accounted for, significant decreases relative to counterfactual were observed only for the Queensboro Bridge site, suggesting localized changes in fine particulate matter from shifting traffic patterns. Spatial patterns of NO ₂ columns from satellite indicate reductions in Manhattan, but substantial increases in the eastern boroughs, particularly in Queens and Brooklyn. Increases in some bordering boroughs, likely due to rerouting of traffic, point to uneven and unintended environmental outcomes across the city. These findings highlight the importance of evaluating both direct and spillover effects when assessing urban environmental policies.CORRESPONDING AUTHORS: Daniel M. Westervelt (danielmw@ldeo.columbia.edu)