Reuters: China warned residents across a large part of its north on Friday to prepare for a wave of choking smog arriving over the weekend, the worst of which is expected over Beijing, prompting the capital to issue its second ever "red alert".
The National Meteorological Centre said the smog would stretch from Xian, home to the world-famous Terracotta Warriors, across part of central China, through Beijing and up into Shenyang and Harbin in the frigid northeast.
The air pollution would begin rolling...