By Jaimie Dalessio
Continued improvements to air quality across the United States appear to extend life expectancy, new research out of Boston's Harvard School of Public Health (HSPH) indicates.
Researchers analyzed 545 U.S. counties over seven years (2000 to 2007) and observed an association between reductions in fine particulate matter and improved life expectancy.
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Particle pollution, or particulate matter (PM) pollution, is a mixture of small particles and liquid droplets, according to the U.S. Environmental Protection Agency (EPA). Small enough to be inhaled, these particles can cause heart and lung health problems. Some types of particle pollution are found near roadways, from vehicle exhaust. Others, called fine particles or fine particulate matter (PM2.5), are 2.5 micrometers in diameter or smaller, and can be found in smoke and haze from forest fires or when gases from power plants and cars react in the air.
While levels of fine particulate matter continue to decline across the country because of air-quality interventions, the pace has slowed since 2000. The HSPH researchers wanted to explore whether more recent, less drastic declines keep benefiting life expectancy. Building on a 2009 study, they extended the study period and used a much larger data set, explains Andrew Correia, a PhD candidate at HSPH and the report's lead author.
The report was published online this week in the journal Epidemiology.
A decrease in the level of PM2.5 was tied to an average increase in life expectancy of 0.35 years, according to their findings. The association, they also observed, was stronger in densely populated urban areas than in rural ones. It also appeared to benefit women more than men.
Those were perhaps two of the most interesting findings, says Correia. "It opens the door for more research to investigate why that is, why we see a strong relationship in those areas."
Correia also says further research could examine exactly how better air quality might improve life expectancy. Past studies have shown that ozone and particulate pollution in the air can irritate people with asthma and chronic obstructive pulmonary disease (COPD), for example. Additionally, a separate study from HSPH, published in April 2012, found that long-term exposure to fine-particle air pollution may increase older adults' risk of hospitalization for lung disease, heart disease, stroke, and diabetes.
"Cleaner Air May Lengthen Life Spans in the United States" originally appeared on Everyday Health.