In their study, the researchers compared life expectancy and air pollution from 1980 to 2000 in US cities.

The researchers noted that people in these cities had been living 2.72 years longer from 2000. The researchers attributed 15% of it to cuts in pollution.

Many previous studies have confirmed that poor quality of air can cause heart and lung disease.

According to UK officials estimates, air pollution is still becoming the cause of reducing lifespan as an average eight months despite cuts in air pollution during the recent years.

Some experts believe that these levels can be reduced almost a half by meeting strict emission targets.

In this study, the researchers from Harvard School of Public Health and Brigham Young University used highly developed statistical models to isolate some other factors for life expectancy changes including wealth, smoking habits and migration from one city to another.

The researchers noted that the cities which had the major shift from pollution to cleaner air had increased an average 9 months in the lifespan of the citizens.

With an average decrease of ten micrograms/cubic meter of pollution there was an average seven months increase in the life expectancy.