A 40-car pile-up in Tianjin, China.<br/> <br />It's just one of many incidents caused by thick smog that's causing havoc across northern China, as pollution reaches alarming levels.<br/> <br />The pile up injured six people and caused a severe traffic disruption for morning commuters.<br/> <br />Adding to the mess, nearly 50 flights were delayed at Tianjin Airport.<br/> <br />Tianjin's air quality monitoring stations reported that air pollution had reached "hazardous" levels through the early afternoon.<br/> <br />Meanwhile, light sleet eased Beijing's notorious pollution on Thursday-- but levels still remained in the "unhealthy" range.<br/> <br />Air quality in the Chinese capital has mostly stayed between "very unhealthy" and "hazardous" for about two weeks on an index that measures particulate matter in the air.<br/> <br />To help combat the smog, Beijing has temporarily shut about 100 heavily polluting factories and took 30 percent of government vehicles off roads.
