Guests at a resort in Nadi, Fiji watch the evening sky as pieces of the Russian space station Mir races across above their heads (top right of screen) as it makes its descent into the earth's atmosphere March 23, 2001. REUTERS/Mark Baker

SINGAPORE (Reuters) - Scientists have discovered a “chemical Equator” that divides the polluted air of the Northern Hemisphere from the largely uncontaminated atmosphere of the Southern Hemisphere.

Researchers from Britain’s University of York found evidence for an atmospheric chemical line about 50 kilometers (30 miles) wide in cloudless skies in the Western Pacific, with levels of carbon monoxide four times higher on the northern side.

The discovery will provide clues to help scientists model simulations of the movement of pollutants in the atmosphere more accurately, and to assess the impact of pollution on climate, the researchers said in a statement in Singapore on Tuesday.

Previously, scientists believed that a cloudy Pacific region where the trade winds meet formed a barrier between the Northern Hemisphere and the clearer air of the Southern Hemisphere.

“Powerful storms may act as pumps, lifting highly polluted air from the surface to high in the atmosphere where pollutants will remain longer and may have a global influence,” said Dr Jacqueline Hamilton, of the University of York.