Although the United States has cut its emissions of smog-forming pollutants by half over the past few decades, smog levels in the Western United States have increased each year. Now, scientists believe that rising emissions in Asia are causing smog in the United States. Asian emissions have tripled over the past decades and are particularly high in China and India. During the spring, storms lift and carry emissions from Asia to the Western United States, causing fog. Listen to learn more about how emissions levels in different parts of the world are changing and how global climate systems move emissions around the Earth and then debate: How can we address global pollution?