Impact of a car-free day on CO2e and PM2.5 emissions in intermediate cities – Ibagué as a case study

Multiple cities in Colombia and Latin America have implemented the car-free day to promote the reduction of environmental impacts of transport and to raise awareness among the population about the negative effects derived from dependence on private vehicles in urban mobility. However, there are few evaluation exercises for these sessions, and the results are not conclusive on their benefits in emissions. In this study, a methodology is proposed to evaluate the change in vehicle emissions on the day without a car and its application to the Ibagué case study is presented. The results for Ibagué show benefits in reducing CO2e emissions between 16% and 60%, for different routes, compared to emissions in normal days; but with an increase in PM10 emissions between 5% and 52%. The results for Ibagué show the importance of taking into account the different factors that determine urban emissions in the design of the program so that it generates positive impacts on emissions. Recommendations are presented for the application of the proposed methodology, and messages about the implementation of the car-free day and its potential environmental effects.