The first study, covering 4,742 people in Switzerland over 11 years, showed that air-pollution cuts from environmental laws added a year of healthy breathing. The second article showed breathing grew more difficult for asthma sufferers who took two- hour walks along London's Oxford Street, thick with exhaust, and improved for those who walked along Hyde Park's traffic-free west side. That survey examined 60 adults from 2003 to 2005.

The Swiss study suggests that cleaner air immediately reduces aging in lungs, even in people who have spent decades smoking and breathing pollution.