Ozone emissions in China are adding to pollution in western US

Ars Technica : Over the past decade, ozone levels over China have been steadily increasing due to the country’s growing population and industrialization. An atmospheric pollutant, tropospheric ozone is created when sunlight reacts with nitrogen oxides, which are produced by car engines and industrial operations. According to a study published in Nature Geoscience, some of that ozone is traveling across the Pacific Ocean and offsetting US efforts to cut air pollution levels. The researchers used data from NASA’s Aura satellite to determine why, despite having reduced emissions of nitrogen oxide by 21% between 2005 and 2010, the western US didn’t see any concomitant reduction in ozone levels. They found that global weather conditions such as storms and El Niño and La Niña patterns disperse ozone around the globe. Therefore, efforts to address issues of air quality will have to be global, not regional.