Beijing is cloaked in smog, April 14. A measurement of PM2.5 - particulate matter with a diameter of less than 2.5 micrograms, which can go deep into the lungs and is extremely harmful to people's health - soared to the hazardous level of 276. The smog that has shrouded the northern parts of China since last week is expected to persist until Thursday, China's environmental watchdog said. The organization recommended that children, the elderly and people with respiratory or cardiovascular diseases stay indoors to reduce the risk from polluted air. [Photo/cfp.cn]