To limit pollution and traffic congestion in Beijing, officials in 2011 imposed a citywide restriction on the number of automobiles residents can purchase annually. That policy has helped limit car sales and emissions. But the system has a loophole: Beijing residents have been going elsewhere in China to purchase cars, then bringing them home. As a new study co-authored by MIT scholars finds, this policy “leakage” reduces the intended impact of the car-restriction system by about 35 percent. So, while Beijing adds fewer new cars per year than it once…
