A 2-decade decline in air pollution in dozens of U.S. cities has added an average of
about 5 months to residents’ lives, according to a new study.
Scientists already had ample evidence of the harmful health effects of air
pollution. Several studies over the past 40 years have linked increased air
pollution to shorter lifespans and higher risks for cardiovascular and lung
disease. The new research provides strong support for an opposite, positive
effect when air pollution levels drop.
Dr. C. Arden Pope III of Brigham Young University and his colleagues at
Harvard School of Public Health focused their attention on fine-particle air
pollution, which generally comes from power plants, industry and car exhaust.
These fine airborne particles measure up to 2.5 microns in size. That’s about
1/30th the width of a human hair.
The researchers identified 51 city regions where fine-particle air pollution
had been measured for several years around the early 1980s and then again about
20 years later, around the early 2000s. The scientists then matched these data
to the residents’ life expectancies during those years, which were calculated
using mortality statistics and population data. Their research was funded by
NIH’s National Institute of Environmental Health Sciences (NIEHS), the U.S.
Centers for Disease Control and Prevention, the U.S. Environmental Protection
Agency and others.
In the January 22, 2009, issue of the New England Journal of Medicine, the
scientists reported that fine-particle air pollution levels dropped in all 51
metropolitan areas during the 20-year study period, and life expectancy rose on
average by nearly 3 years. After adjusted for income, education, smoking and
other factors that affect longevity, the scientists found that improved air
quality accounted for up to 15% of the overall increase in lifespan, or an
average gain of 4.8 months of life.
For every decrease of 10 micrograms per cubic meter of fine-particle
pollution, the average life expectancy of city residents rose by more than 7
months. Overall, in all 51 cities, particulate air pollution declined by an
average of 6.5 micrograms per cubic meter. However, in cities like Pittsburgh and Buffalo,
where fine-particle pollution dropped most dramatically—by about 14 micrograms
per cubic meter—the improved air quality appeared to boost longevity by nearly
10 months. Even cities that started off with relatively clean air, like Albuquerque, gave
residents a modest lift in lifespan when air quality improved slightly during
the study period.
“We find that we're getting a substantial return on our investments in
improving our air quality,” says Pope. “Not only are we getting cleaner air
that improves our environment, but it is improving our public health.”
