A study published today in the New England Journal of Medicine shows that cleaner air is responsible for lengthening the lives of the average American by nearly five months. The researchers report that improvements made in air quality over the past two decades have added 21 weeks to the life expectancy of the average American. It’s the first study to clearly demonstrate that reducing air pollution leads to longer lives.

Overall, the average life expectancy of Americans has risen 2.72 years since the early 1980s, in part because of reduced smoking rates and improved socioeconomic conditions. But the researchers found that 15 percent of that increase in longevity, about 21 weeks, is attributable to reductions in air pollution. Other studied indicate that this increase in longevity is likely due to declines in heart and lung diseases that are associated with air pollution.

The study looked at data on particulate pollution levels and life expectancies from 51 metropolitan areas across the nation during the 1980s and 1990s. On average, particulate levels fell from 21 micrograms per cubic meter of air to 14 micrograms per cubic meter in the cities studied, while the life expectancy increased by nearly three years.

What’s more, the communities that saw larger decreases in particulate levels also showed greater increases in life expectancy. In fact, the researchers found a reliable relationship between the two factors: for every reduction of 10 micrograms per cubic meter of particulate pollution in a city, its residents' average life expectancy increased by more than seven months. Thus, in Pittsburgh and Buffalo where the decrease was close to 14 micrograms per cubic meter, the life expectancy increased by nearly 10 months.

In 1970, the U.S. instituted the Clean Air Act, which gave the federal government power to institute national standards for air pollution. The law led to the development of catalytic converters on vehicles and new standards for factory emissions. While all of this came at great cost, researchers say that findings such as those released today make it all worthwhile.

Even better news is that data from the Environmental Protection Agency show that particulate levels have dropped another 11 percent nationally since 2001, the final year of data that was included in the study.

For more information on lung diseases related to air pollution, join the Healia Health Community for Lung Diseases. To find out more about heart disease, consult the Healia Health Guide on Heart Disease.

_{Photp: pfala, Flickr, Creative Commons}