Cleaning up the air, a new study suggests, helps people live longer.

In fact, research led by Brigham Young University's C. Arden Pope and published in today's edition of the New England Journal of Medicine showed that Americans lived about five months longer on average thanks to 20 years of improvements in air quality.

Pope called the correlation "remarkable."

"It's a good-news kind of study," he said. "At least what we've done [to improve air quality] seems to be having a real return on investment."

The life expectancy analysis is the latest in a series of groundbreaking studies by Pope, an epidemiologist, and colleagues from the Harvard School of Public Health about the relationship between air pollution and health.

Their research has found previously, for instance, that pollution trends influence hospital admissions for infants, hasten death among heart and lung disease sufferers and worsen heart trouble among people exposed to spikes of fine-particle pollution. And, while often controversial, Pope's work has stood up to scrutiny even by the U.S. Supreme Court, which partly based its decision on a key national pollution standard based on past studies by the Harvard-BYU team.

The latest study compared life expectancy data with air pollution data from 1979-83 and from 1999-2000. Adjusting for changes in population, income, education, migration, demographics and cigarette smoking, the analysis looked at trends in 21 cities, including Salt Lake City.

In general, the more polluted the city, the greater the benefits of cleaner air, the study found. In cities with the dirtiest air, cleaner air added about 10 months to life expectancy.

Overall, the study says, Americans are living about 2.72 years longer, with about five months added on average, or about 15 percent.

In Salt Lake City, life expectancy increased by more than four years during a period when average PM 2.5 pollution decreased just over 3 micrograms per cubic meter of air, based on data from the study. (PM 2.5 is a pollutant made up of microscopic soot primarily from the exhaust of cars, trucks and industry.)

The impact of pollution cuts? Over two months longer life expectancy.

"The results suggest reductions in air pollutants have resulted in improvements in life expectancy," said Pope. "They also show there's room for improvement."

The study comes out that a time when Pope's hometown has been choked for more than a week with high levels of PM 2.5. And, while he noted that measured pollution has decreased even with dramatic increases in population on the Wasatch Front, "we need to be very vigilant."

Salt Lake City pulmonologist and director of the Utah Physicians for a Healthy Environment Richard E. Kanner read the latest Pope study and agreed that it had a positive message -- even if the air outside is unhealthful.

"You clean up the air," he said, "you get rewarded, you live longer."

A member of the state Air Quality Board for nine years and its chairman from 1995-97, he had one criticism: Pope overplayed the loss of life from smoking and underestimated the impact of pollution. But he added: "These are very complicated types of studies."

As the pollution-life expectancy study was publicly released Wednesday, lawmakers on Utah's Capitol Hill dug a little harder into Department of Environmental Quality funding to help address next year's budget deficit. While state agencies are being asked to cut 7.5 percent from their current-year budgets and 15 percent from next year's expenses, the DEQ was asked to trim nearly 2 percent more -- roughly the cost of two employees -- to help protect the Utah National Guard and veterans' services.

fahys@sltrib.com