Conference Agenda

A common strategy to reduce exposure to pollutants during critical air quality events in Latin America is to temporarily adjust transportation policies. Medellín, Colombia's second-largest city, and the Aburrá Valley Metropolitan Area implemented a short-term driving restriction plan in 2017. Unlike other cities, this plan not only banned cars but also restricted motorcycles and trucks. The restrictions quickly became stricter for older vehicles. We use a two-way fixed effects model to empirically evaluate the effectiveness of this plan between 2017 and 2019. We assess the impact on pollutant concentrations, vehicle trips, noise, and changes in regular on-road tests of vehicle environmental performance. Our results show the plan reduced air pollution by 3% to 26% for several pollutants. Red alerts, which implemented the strictest bans, showed the largest improvement in air quality, especially for particulate matter. Reductions in air pollutants appear greater when restrictions apply to trucks, older vehicles, or when bans include additional license plate numbers, rather than using generalized restrictions. Vehicle trips and noise also declined. Additionally, we found an increase in on-road vehicle testing. Unlike regular driving restriction programs that provide mixed evidence regarding their effectiveness, our findings suggest that differentiated restrictions are effective. Focusing the strictest bans on the most polluting vehicles reduces air pollution during short-term episodes of poor air quality.