Continuing declines in air pollution are linked to increasing life expectancy, a national study has found.
From 2000 to 2007, air pollution, as measured in concentrations of particulate matter less than 2.5 micrometers in diameter, has continued to decrease, although not as rapidly as in the 1980s and '90s. But even the slower rate of decrease is apparently lengthening life expectancy.
The study, published online last week in the journal Epidemiology, used data from 545 counties nationwide, both metropolitan and rural, and found an average decrease of 1.56 micrograms per cubic meter in particulate pollution over the eight years. At the same time, life expectancy increased an average of 0.84 years.
Of course, many other factors contribute to increased life span besides cleaner air. The researchers controlled for smoking prevalence, income and other health and economic factors. They estimated that about 18 percent of the increase in life span can be attributed to reduced air pollution.
"What this means is that even if particulate pollution has been declining in recent years at a slower rate, even if we have already done a lot of cleanup, still continuing to clean is important," said the senior author, Francesca Dominici , a professor of biostatistics at the Harvard School of Public Health. "Our paper is strong evidence that additional investment in cleaning the air is beneficial."