The monitoring data for the PM2.5 measure of air quality is seen released on the official website of the Beijing Environment Protection Monitoring Center in Beijing, capital of China, Jan. 21, 2012. Beijing's environment authority on Saturday released the PM2.5 measure of air quality, which is considered stricter than its previous standard of PM10. Particles 2.5 microns or less in diameter (PM2.5) are referred to as "fine" particles and are believed to pose greater health risks than larger particles because they can embed deep in people's lungs. (Xinhua/Gong Lei)