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Harvard study: Air pollution cuts increased life expectancy

Print | Comments () Posted by Gideon Gil January 21, 2009 05:18 PM

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By Bina Venkataraman, Globe Correspondent

UPDATE on THURSDAY, JAN. 22: To view the data for individual cities, including Boston, check out this interactive graphic.

People living in cities where air pollution decreased in recent decades saw their life expectancy increase an average of five months as a result of cleaner air, a new study from the Harvard School of Public Health and Brigham Young University strongly suggests.

The researchers looked at the amount of small particle pollutants in 51 US cities, including Boston, Worcester, and Providence, R.I., during the '80s and '90s and found that the predicted lifespan increased most significantly in cities where air quality also increased most dramatically.

The study, which will appear in tomorrow's New England Journal of Medicine, signals that efforts to curtail the small, toxic particles spewed by power plants, factories, cars, and trucks and inhaled by city-dwellers had significant health benefits over those two decades. Several clean air advocates and public health specialists say the results also show that stronger standards for air pollutants are necessary.

"We had known with reasonable confidence for a while now that air pollution is bad for people's health," said Majid Ezzati, a professor at the Harvard School of Public Health and one of the study's authors. "The question still lingering was: Does lowering pollution have health benefits? The answer is yes."

Boston's share of fine particulate matter decreased about 7 micrograms per cubic meter of air between 1980 and 2000, which was about the average amount that small particle pollution dropped among all the cities evaluated across the nation. Average life expectancy in Boston increased by more than three years during that time period, about five months of which the researchers found could be attributed to cleaner air.

Other factors that have improved predicted lifespans in recent decades range from medical advances, education, and income growth to changes in lifestyle including smoking and eating habits.

Life expectancy does not directly indicate how long people live. Rather, it predicts how long the average person in a population would live if the death rate at a given time persisted for the person's lifetime.

Kirk Smith, a professor at the School of Public Health at the University of California in Berkeley who was not affiliated with the study, said that "it adds another nail in the coffin that particulate air pollution has a significant impact on health. After all, we do spend tens of millions of dollars controlling air pollution, so we better make sure it works."

If, as the study suggests, cleaner air improves predicted lifespan, life expectancy has likely increased further in many parts of the nation during this past decade. Since 2000, air monitoring data shows that the national average concentration of fine particles has decreased 11 percent, said Cathy Millbourn, spokeswoman for the US Environmental Protection Agency.

Still, clean air advocates and some public health specialists say that the Bush administration did not do enough to decrease small particulate matter pollution

"The science suggests that there's a need for additional and more stringent regulation of particulate air pollution," said Doug Brugge, a professor at Tufts University School of Medicine. "In New England and nationally, particulate pollution remains a significant concern."

According to the Clean Air Task Force, a Boston-based nonprofit group, 24,000 people die each year as a result of small particle pollutants from power plants and another 21,000 people die from diesel exhaust's small particles in the country.