Nature World News: Beijing registered air pollution levels that are at least three times higher than the "safe" level advised by the World Health Organization. The latest figures on the particulate matter in air were released by the Ministry of Environmental Protection (MEP). The report included data from 74 cities. The agency said that the concentration of PM2.5 particulates in 74 cities was about 76 micrograms per cubic meter for the first six months. According to the WHO this concentration should not be over 25...