article_snippet: Air pollution has long been a problem in China, where cities are often overcome with thick smog .
article_snippet: China's 'Air Pollution Prevention Law' stipulates that: coal, pulverized coal, combustible waste, direct burning of biomass fuels (trees, straw, sawdust, rice husk etc) are all high-polluting fuels.
article_snippet: China has for years been hit by heavy air pollution, caused by enormous use of coal to generate electricity to power a booming economy - the world's second largest - and more vehicles on the roads.
article_snippet: Air pollution is increasingly acute in Chinese cities, including in Wuhan in central China's Hubei province .
article_snippet: It has become a major source of popular discontent among Chinese citizens, leading the government to declare a 'war on pollution' and vow to reduce the proportion of energy derived from fossil fuels.
article_snippet: Earlier this month Under the Dome, a film about China's notorious smog, went viral with more than 155 million views in just one day.