The cleaner the air you breathe, the longer you will live. But how much longer?    

By NICHOLAS BAKALAR

Published: January 21, 2009 








More Vital Signs ColumnsResearchers 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 associated with an increase of more than seven months in 
average life expectancy. 

Over all, life expectancy increased by an average of two years and eight months 
in the areas studied. Drawing on data from this and other studies, the 
researchers estimated that five months of the increase was attributable strictly 
to improvements in air quality. 

“This is a large, nationwide natural experiment,” said C. Arden Pope III, a 
professor of economics at B.Y.U. and the lead author of the study, which is to 
be published on Thursday in The New England Journal of Medicine. 
“We did an intervention — improved air quality — and the question is, ‘Did we 
get a return?’ ” he continued. “The bottom line is yes, it looks like we did. 
Our efforts to clean up the air are helping.”


More Articles in Health » A version of this article appeared in print on January 
27, 2009, on page D6 of the New York edition. Download the historic Nov. 5 issue 
of The New York Times Electronic Edition.