This weekend is carmageddon II in Los Angeles, when a sizable, well-trafficked chunk of the popular 405 freeway will again be closed to all motor vehicles. The previous one didn’t produce the traffic snarls that were feared, and it also didn’t produce something else—smog.
A new report from UCLA found that during that first closure of a 10-mile stretch of the 405 last year, air quality near the freeway improved immensely within minutes. Levels were as much as 83 percent better than on other weekends when the freeway was as clogged as ever.
What’s that sound? It’s your lungs cheering.
“The air was amazingly clean that weekend," Suzanne Paulson, a professor of atmospheric and oceanic sciences at UCLA said in a news release. "Our measurements in Santa Monica were almost below what our instruments could detect, and the regional effect was significant. It was a really eye-opening glimpse of what the future could be like if we can move away from combustion engines.”
Because people were afraid of gridlock everywhere, they generally stayed off major highways around Southern California during carmageddon I. The result: air quality improved on average 25 percent in such far-flung areas as Long Beach, Santa Clarita, Ventura and Yucaipa, and it improved 75 percent in areas of West L.A. and Santa Monica. Those numbers even surprised the researchers.
But the effects were short-lived: by the following week, the skies were back to their usual smogginess.
What exactly are we taking in when we breathe smoggy air? Let’s start with ground-level ozone, which can react with the fluid lining of the respiratory tract, possibly causing inflammation. Fine carbon-based particles can also become irritants, and latching onto them may be polyaromatic hydrocarbons, known to cause tumors in lab animals.
While air quality has improved vastly in the Los Angeles basin since the 1970s, we’re hardly out of the woods. The increased health risks of being exposed to near-roadway pollutants, the researchers said, include heart attacks, strokes, asthma and even diabetes
Among the fine particles the scientists measured were ones known as PM2.5, which include tailpipe emissions. What’s unique about these particles is that they can travel farther from the freeway and hang around longer than other ultrafine particles.
"There is no safe level of PM2.5 concentrations, where you would no longer observe health impacts, so any reduction is an improvement," said associate professor of environmental health sciences Yifang Zhu. “This study shows that with such dramatic traffic reductions, there are specific air-quality improvements. It gives policymakers and the public incentives to put more effort into reducing traffic emissions.”
Are you thinking of switching to a hybrid car to help improve air quality? Let us know in the comments.