The New England Journal of Medicine study matched air pollution and life expectancy statistics from 51 cities between 1980 and 2000.
Scientists found people living 2.72 years longer by 2000 - 15% of which they attributed to falls in pollution.
Studies have found poor air quality can worsen lung and heart disease. UK researchers have suggested that poor air quality can reduce life expectancy by up to eight months. This is in spite of improvements in air quality over the past few decades.
The study, carried out between Brigham Young University and Harvard School of Public Health, used advanced statistical models to separate out the various other factors behind changes in life expectancy, such as smoking and wealth, as well as to account for migration to and from the cities studied.
The research focused on "PM 2.5" pollution - which measured levels of tiny particles with a diameter one-twentieth of the width of a human hair.
These fine particles can travel deeply into the lungs, and have been linked with the worsening of asthma and heart disease.
The researchers found that in those cities with the biggest shift from polluted to clean air, this had yielded an average of 10 more months lifespan to its residents.
For every decrease of 10 micrograms per cubic metre of particulate pollution, life expectancy increased by more than seven months.
