Take a deep breath.  Lots of them.  You'll be breathing longer these days, thanks to improved air quality.  Researchers at Brigham Young University and the Harvard School of Public Health, writing in the New England Journal of Medicine, say that since the introduction of the Clean Air Act in 1978, Americans' life expectancy has increased by 2.72 years.  Although changes in smoking habits and better socioeconomic living conditions are a major factor in our increased longevity, the scientists note that as much as five weeks of our lengthened lifespans are due to better air because of cuts in auto emissions, steel mills, diesel engines and coal-fire power plants.

Excerpts from June 2009 newsletter.