Studies have found poor air quality can worsen lung and heart disease.
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.
For every decrease of 10 micrograms per cubic metre of particulate pollution, life expectancy increased by more than seven months.
Dr C Arden Pope, one of the study researchers, said it was a "remarkable" increase.
"We find that we're getting a substantial return on our investments in improving our air quality.
"Not only are we getting cleaner air that improves our environment, but it is improving our public health
