Growing pollution leads to "global dimming"

Visibility on clear days has declined in much of the world since the 1970s thanks to a rise in airborne pollutants, scientists said on Thursday.

They described a "global dimming" in particular over south and east Asia, South America, Australia and Africa, while visibility remained relatively stable over North America and improved over Europe, the researchers said.

Aerosols, tiny particles or liquid droplets belched into the air by the burning of fossil fuels and other sources, are responsible for the dimming, the researchers said.