China releases Beijing pollution data after too much critics
For the first time Beijing has publicly revealed PM2.5 data and follows a clamor of calls by citizens on social networking sites tired of breathing in gray and yellow air. The U.S. Embassy measures PM2.5 from a device on its rooftop and releases the results, and some residents have even tested the air around their neighborhoods and posted the results online.
Beijing's environmental monitoring center posted on its website readings of PM2.5 — particulate matter less than 2.5 micrometers in size. Such small particulates can penetrate deep into the lungs, so measuring them is considered a more accurate reflection of air quality than other methods.