skade88 writes "This story should remind us all that air pollution controls are not just about addressing global warming. They also help us have cleaner air and fewer health problems resulting from smog and haze. Starting earlier this month, Beijing, China started having worse than normal air pollution issues. On January 14, 2013 the U.S. embassy's air pollution sensors in Beijing found the density of the most dangerous small air particles, PM 2.5, at 291 micrograms per cubic meter of air. The World Health Organization's guidelines for air pollution state that PM 2.5 above 25 micrograms per cubic meter of air is dangerous to a person's health. To put the problem into perspective, NASA has released two orbital photos of Beijing showing before-and-during images of the air pollution. The photo from January 4 shows parts of Beijing still visible from space. The photo from January 14 shows nothing but a huge, thick cloud of haze with no buildings visible."