Scientists studied LA’s air quality during the “Carmageddon” freeway shutdown and found some really telling, yet unsurprising, data:

The researchers found that particulate matter dropped significantly within minutes of the road closure (accordingly, it ramped back up the moment traffic resumed). And this is significant for policy reasons. When it comes to the environment, we’re often talking about making difficult or expensive investments in the short term that may not pay off for years to come. But this research underscores that changes in transportation policy or vehicle technology could yield practically instantaneous improvements in the quality of air (and quality of life) for people today.