The Effect of Saturday Driving Restrictions on Air Quality in Mexico City

Policymakers around the world are turning to driving restrictions in an effort to address urban air pollution. The exact format differs across cities, but most programs restrict driving once or twice a week during weekdays, with no restrictions on weekends. This paper examines Mexico City's driving restrictions which were expanded to include Saturdays in 2008. The expansion marks a significant change for a program which during the previous twenty years had always applied to weekdays only. Overall, there is little evidence that the program expansion has improved air quality on Saturdays. The two most important pollutants from a health perspective are airborne particulates and ozone, and neither pollutant decreases when the program is expanded. There is a modest decrease for some other pollutants on Saturday afternoons, but no decrease for any pollutant on Saturday mornings when pollution tends to reach its daily peak. There is also no evidence that the expansion of the program increased subway, bus, or light rail ridership, despite optimism that drivers would substitute to public transportation. These results add to a growing body of evidence that suggests drivers will find ways to circumvent vehicle rationing programs.

Speaker: Lucas Davis, UC Berkeley