Beijing's Skyline

BEIJING, CHINA - FEBRUARY 19: A general view of the skyline of central business district on February 19, 2013 in Beijing, China. Large amounts of organic nitrogen compounds were found in Beijing smog in January, the worst month in recent years. Most alarming is that the Chinese Academy of Sciences says they've found organic nitrogen particles, a key component in the deadly photochemical smog in Los Angeles in the 1950s and the Great Smog in London. (Photo by Feng Li/Getty Images)