People in the Pittsburgh region are living longer due in no small part to reductions of fine particle soot emissions, according to an article published today in the New England Journal of Medicine.
Cleaner air in the last two decades has added an average of five months to the life expectancy of residents in 51 urban areas in the United States, the article said, and 10 months to the life expectancy of Allegheny County residents because air there has improved more than in any other area of the country.
The federally funded study conducted by researchers at Brigham Young University and the Harvard School of Public Health found that reducing pollution has resulted in an observable, quantifiable, improvement in public health and that further pollution reductions will continue that trend.
“Although previous studies have provided evidence that air pollution is a risk factor for respiratory and cardiovascular disease, this is the first study that provides direct empirical evidence that long-term reductions in air pollution contribute to significant, measurable increases in life expectancy,” said Dr. C. Arden Pope III, of Brigham Young University and the study’s lead author.
“Not only do the results indicate that past reductions in air pollution have improved life expectancy, but they suggest that in most U.S. cities, and cities throughout the world, there are opportunities for further improvements in life expectancy due to continued reductions in air pollution.”
The average life expectancy in the U.S. is 77.8 years, according to the National Center for Health Statistics, and the life expectancies in the 51 urban counties studied rose by an average of approximately 2.74 years from 1980 through 2000, so the varied reductions in levels of the tiniest airborne particles are only one factor in that increase.
But Dr. Pope said the study’s findings show that investments made in pollution controls to improve air quality have paid off.
“There are multiple overlapping factors that influence life expectancy, making it difficult to isolate effects of specific medical, public policy, environmental or other changes on life expectancy,” Dr. Pope said. “However, in this analysis it was surprising how robust the air pollution-life expectancy relationship was.”
The fine airborne particles are called PM 2.5 because they are 2.5 micrometers in size or smaller — so small that several hundred could fit on the period at the end of this sentence. The particles can be emitted directly from coal-burning power plants, other industrial sources or vehicles, or form in the atmosphere from chemical reactions involving sulfur dioxides and nitrogen oxides emitted from those same sources.
Such fine soot pollution can be breathed deeply into the lungs and cause a number of serious health problems, including asthma, heart attacks, pulmonary disease and premature death, as well as increased hospital admissions and emergency room visits for respiratory and cardiovascular problems.
The World Health Organization estimates that 1.4 percent of all deaths are the result of particulate air pollution.
The new study used U.S. Environmental Protection Agency research data on fine airborne particulates, collected in the 51 urban areas from 1979 through 1983 and compared it to data from 1997 through 2001. It found that Allegheny County’s PM 2.5 levels had declined from near 30 micrograms per cubic meter to a little more than half that number, though still higher than the federal health standard of 15 micrograms per cubic meter.
The Pittsburgh region started out higher than any of the other 50 metropolitan areas in the study and reduced its PM 2.5 levels the most. The study found that areas with the largest reductions in fine particle emissions would have larger increases in life expectancy, and Pittsburgh’s rose by more than three years.
“That’s a phenomenal improvement and shows that air pollution control pays off in public health,” said Guillermo Cole, a spokesman for the Allegheny County Health Department, which monitors air quality and enforces pollution controls. “They’re talking about adding almost a year to people’s lives. That just reinforces the meaning and purpose of the work we do in public health.”
He said all areas of the county have seen “dramatic” improvement in air quality, particularly for PM 2.5, over the last 25 years, partly because there is less industry operating in the county and partly due to better pollution controls.
Catherine Milbourn, an EPA spokeswoman in Washington, D.C., said the study will provide critical health information that will help the agency set fine particle standards that protect public health. The existing standard has been criticized by some scientists and environmental groups for not being strict enough.
Since 2000, federal air monitoring data shows that the national average concentration of fine particles has decreased 11 percent.