Beijing: Before and after air pollution Before and after images showing the extent of Beijing’s air pollution. As winter approaches, the air quality in China’s capital reaches hazardous levels every year. According to Greenpeace East Asia, China’s efforts to cut air pollution have led to “massive reductions” in smog but it remains a severe problem, posing health risks for the cardiovascular system and an increase in the probability of cancer. OnFriday, Beijing's authorities issued a yellow alert for heavy air pollution in the next three days , asking citizens to take the necessary precautions. IMAGES