Paulson and colleague Yifang Zhu measured pollutants in the air during Carmageddon (Los Angeles shut down a 10-mile stretch of one of its busiest highways) last year and have recently released their pretty astounding findings. Air quality near the normally busy highway improved by 83 percent that day last July, relative to comparable weekends.

Empty 405 freeway

Los Angeles closed a 10 mile section of Highway 405 for 48 hours last week to complete the project. Photo by Ed Kwon.

“In the broadest picture,” Paulson says, “what these measurements gave me was a view into what a future would be like where either people were using much more mass transit, and/or they’re driving vehicles that are really very clean and that remain very clean throughout their lives.”

Typical internal combustion engine cars, of course, tend to get dirtier as they age.