In pictures: Smog hits BeijingPublished24 February 2014Shareclose panelShare pageCopy linkAbout sharingImage caption, Air pollution has shrouded parts of northeast China since Friday, leaving residents choking on hazardous levels of smog.Image caption, Particulate readings in Beijing soared to 15 times WHO-recommended safe limits on Friday - reaching "orange" levels, the second-highest possible.Image caption, The smog has persisted through the weekend, shrouding other Chinese cities including Hangzhou.Image caption, By Monday the alert level was down to "yellow", but many residents wore protective masks as they went about their daily lives.Image caption, In response, the Beijing government has ordered checks on construction work and polluting industries, and banned open-air barbecues in the city.Image caption, Residents have lived with the pollution for several years - and it tends to get worse in winter.Image caption, High levels of smog can be harmful to health, the WHO has warned, causing respiratory illness in vulnerable people.