Beijing’s air pollution is far below acceptable World Health Organization levels with the Chinese capital a month away from hosting the Winter Olympics –- but environmental data shows its skies have improved dramatically in recent years. The city declared a “war on pollution” after winning the Olympics bid in 2015, shutting down dozens of coal plants and relocating heavy industries in order to shed its status as one of the world’s most polluted cities. China also hopes to use the Games to showcase its green credentials and has built dozens of wind and solar farms to power the sporting spectacl…