Taking Cars Off the Roads = Instantaneous Air Quality Improvements

An eye-opening glimpse of what the future could be like if we can move away from combustion engines
Matt Stevens, Los Angeles Times, September 28, 2012

Los Angeles shut down a 10-mile stretch of one of its busiest highways, the 405, for a weekend in July 2011. Drivers stayed away in dramatic numbers – not only from the 405, but also throughout the entire region.

Last Friday, Suzanne Paulson and Yifang Zhu of UCLA's Institute of the Environment and Sustainability released their research on air pollutants measured during "Carmageddon 2011". 

Air quality near the closed 10-mile portion of the 405 freeway reached levels 83% better than typical weekends.  Elsewhere in West Los Angeles, the improvement was equally dramatic. Air quality improved by 75% in parts of West Los Angeles and in Santa Monica, and by 25% throughout the entire region, suggesting that large numbers of residents stayed off the road in those areas as well.

The researchers found that particulate matter dropped significantly within minutes of the road closure (accordingly, it ramped back up the moment traffic resumed).  There's little heavy industry around this stretch of the 405 freeway, underscoring that changes in transportation policy or vehicle technology could yield significant air quality improvements.

Read the complete article here, and another take here.