Decades ago Mexico City’s air pollution was so poor, birds would fall out of the sky — dead. Locals said living there was like smoking two packs of cigarettes a day, according to one report. In response, Mexico City took several steps to try to improve air quality including restricting driving one or two days during the weekdays. The program has had negligible results.
In 2008, the city added driving restrictions on Saturdays in hopes of moving the needle but according to new research by Lucas W. Davis, an associate professor at UC Berkeley’s Haas School of Business, extending the program one more day also isn’t working.
“Saturday driving restrictions are a flawed policy. It’s a big hassle for people and does not improve air quality,” says Davis, who is also the faculty director at the Energy Institute at Haas.
The study, “Saturday Driving Restrictions Fail to Improve Air Quality in Mexico City,” published in Scientific Reports, is the first to examine the effects of restricted driving on Saturdays. It compares pollution levels of eight major pollutants before and after the program went into effect. Having fewer motorists on the road on Saturdays led to close to zero impact. Proponents of the Saturday program had estimated vehicle emissions would be reduced by 15% or more.
Mexico City has the worst air quality in the Western Hemisphere with particulate levels that are three to four times higher than in New York, Los Angeles, São Paulo, or Buenos Aires, the paper states.