New York Times: The cleaner the air you breathe, the longer you will live. But how much longer? Researchers at Brigham Young University examined changes in life expectancy in 51 metropolitan areas, comparing those figures with improvements in air quality in each region from the early 1980s to the late 1990s. After controlling for smoking, socioeconomic factors and other variables, the scientists found that each decrease of 10 micrograms of pollutant particles per cubic meter of air was …