China's air pollution problems, caused largely by coal burning, can be felt across the globe. In the springtime, dust storms originate in the Gobi desert and travel through the vast country, picking up particulates and other polluting emissions. These storms seep into neighboring Korea and even travel by jet stream across the ocean into Japan and as far as central North America. While heavy particles drop out of the clouds before crossing the Pacific Ocean, smaller particles containing measurable quantities of arsenic, copper, lead, zinc, sulfuric acid, and mercury can travel on the jet stream for more than a week.
—Karen C. Courtnage