It’s amazing how much we affect the planet and recognize only in brief glimpses. From a good article from earlier this summer:
"Nature doesn’t normally present the kind of opportunity that "Carmageddon" did in Los Angeles last year, an opportunity to catch a glimpse of atmosphere that’s typically saturated with pollutants on a suddenly pristine day. As you’ll recall, Los Angeles shut down a 10-mile stretch of one of its busiest highways, the 405, for a July weekend in 2011 (the city reprised the closure this past weekend to finish the project). Locals predicted apocalyptic gridlock. Instead, out of fear of just such a scene, drivers stayed home in dramatic numbers – from the 405, but also throughout the entire region.”
"Air quality near the normally busy highway improved by 83 percent that day last July, relative to comparable weekends. Elsewhere in West Los Angeles, the improvement was equally dramatic. Air quality improved by 75 percent on that side of the city and in Santa Monica, and by 25 percent throughout the entire region, as a measure of the drop in ultrafine particulate matter associated with tailpipe emissions."
Though I’m generally fascinated by all forms of transportation, urban walking is one that I’ve only considered briefly up until the last month or so. Looks like Tom Vanderbilt (of Traffic fame) is working on a new walking book. Here’s a great article about the science behind studying walking.