Asian air pollution 'affects weather in Northern Hemisphere'
15 April 2014 Last updated at 15:54 BST
Air pollution in China and Asia is affecting weather patterns across the Northern Hemisphere, according to a study.
Scientists found that pollutants strengthen storms above the Pacific Ocean - those storms then feed into weather systems in other parts of the world.
The effect was most pronounced during the winter.
Mariko Oi reports.